When buying fasteners, understanding their material is a very important step. Common material choices include carbon steel and stainless steel, what is the difference between the two? Let's explore this in detail.

Carbon steel and stainless steel are both important categories in steel products and are widely used in various industrial and construction fields. However, they differ significantly in composition, performance and use.

First, what is carbon steel and alloy steel?

Carbon steel: Carbon steel is an iron-carbon alloy with a carbon content of less than 2.11%. In addition to iron and carbon, it also contains limited amounts of silicon, manganese, phosphorus, sulfur and other impurity elements, but does not contain other alloying elements. Carbon steel accounts for about 80% of the total production of steel, because of its low production cost, wide performance, is widely used in construction, Bridges, vehicles, machinery manufacturing and other fields.

Alloy steel: Alloy steel is steel with one or more alloying elements added on the basis of carbon steel, such as chromium, nickel, tungsten, titanium, vanadium, manganese, copper, aluminum, molybdenum and so on. The addition of these elements can significantly improve specific properties of steel, such as increasing hardness, improving corrosion resistance, increasing strength, improving formability and changing weldability. Alloy steel accounts for about 20% of total steel production and is widely used in occasions requiring special properties, such as petrochemical, medical equipment, aerospace and other fields.

Classification of carbon steel and alloy steel

Classification of carbon steel: According to the different carbon content, carbon steel can be divided into low carbon steel, medium carbon steel and high carbon steel three categories. Low carbon steel carbon content ≤0.25%, common grades are A3 steel, Q215A steel, Q235 steel, etc., mostly used to manufacture some common structures and parts; Medium carbon steel carbon content is between 0.25% and 0.45%, common grades are 35# steel, 45# steel, etc., suitable for mechanical parts and tools; High carbon steel, with a carbon content of > 0.45%, is rarely used in the manufacture of fasteners because of its high hardness but poor toughness.

Classification of alloy steel: According to the total content of alloying elements, alloy steel can be divided into low alloy steel (total alloy content ≤5%), medium alloy steel (5% < total alloy content ≤10%) and high alloy steel (total alloy content > 10%). Low alloy steel is often used to make some structural parts that require high strength, while medium alloy steel and high alloy steel are used in more demanding environments, such as high temperature, high pressure, strong corrosion and so on.

Three. Characteristics of carbon steel and alloy steel

Characteristics of carbon steel: The performance of carbon steel mainly depends on its carbon content. The higher the carbon content, the strength and hardness will increase correspondingly, while the plasticity, toughness and weldability will decrease. The advantages of carbon steel include good plasticity and weldability, cheap price, easy to smelt and process; The disadvantage is that its strength is relatively low, poor hardenability, low temperature resistance and corrosion resistance are insufficient, and the magnetic conductivity is low, and it is easy to be magnetized in the magnetic field.

Characteristics of alloy steel: By adding different alloying elements, alloy steel can obtain a variety of excellent properties. Its advantages include good comprehensive performance, suitable for special purposes, high strength, high toughness, good hardenability, wear resistance, corrosion resistance, low temperature protection and high temperature protection and non-magnetic; The disadvantage is that the price is high, and the molding process and heat treatment process are complex.

Fourth, the use of carbon steel and alloy steel

Use of carbon steel: Carbon steel is widely used in the manufacture of various building components, containers, boxes, furnace bodies and agricultural machinery and other small-bearing parts. For example, Q215A steel is often used in the manufacture of washers, Q235 steel is suitable for the manufacture of bolts, nuts, screw sleeves, cotter pins and rivets, etc., mainly used in some ordinary products without hardness requirements; The 35# steel and 45# steel belong to the high-quality carbon steel structure, which is mostly used to manufacture 8.8 bolts and 8 nuts and 8.8 hex fasteners.

Use of alloy steel: Alloy steel is usually used for occasions that require high performance, such as parts of transportation vehicles (automobiles, ships, aircraft, etc.), parts of mechanical equipment (machine tools, rockets, missiles, etc.) and various rolling bearings, tools, measuring tools, springs, molds, etc. In special environments, such as high temperature, high pressure and strong corrosion conditions working equipment (such as steam turbines, boilers, chemical equipment, etc.), also made of alloy steel. The alloy steel used to manufacture fasteners mainly includes some high-strength bolts and nuts, such as 30CrMo and 40Cr of 10.9 grade, 35CrMo and 42CrMo of 12.9 grade, etc. These materials are often used in the manufacture of high load bearing bolts, stud bolts, screw sleeves, pins, connecting rod screws, nuts, etc.

In summary, when selecting fastener material, carbon steel or alloy steel can be selected according to the specific use needs. If the application scenario does not have high requirements for the strength and accuracy of the material, and the cost factor needs to be considered, then carbon steel may be a more suitable choice. If the application environment is more severe, especially in the case of high requirements for strength, durability and corrosion resistance, the choice of alloy steel is undoubtedly more appropriate.

Q390B steel plate is a kind of low-alloy high-strength structural steel, which not only has the characteristics of high-strength steel, but also belongs to the category of low-carbon steel. Q390B, with its excellent mechanical properties and wide range of applications, has become one of the indispensable materials in modern industry.

Q390B has a high yield strength, which means that it can maintain the stability of the structure when subjected to external forces and is not prone to plastic deformation. In addition, it also has good fatigue resistance, which gives it a long service life under cyclic loads. Q390B also exhibits high toughness and a low brittle transition temperature, maintaining good toughness even at low temperatures and reducing the risk of fracture.

In addition to mechanical properties, Q390B also has good cold forming properties and welding properties. It is easy to process into various shapes and sizes of components, and can maintain its excellent performance under different welding processes. This gives the Q390B greater flexibility and adaptability in the manufacturing process. In addition, Q390B also has good corrosion resistance and certain wear resistance, which can be used in harsh environments for a long time without being affected by corrosion and wear.

The implementation standard of Q390B steel plate is GB/T1591-2018, which specifies the requirements of its chemical composition, mechanical properties, smelting methods and delivery status. Depending on the application requirements, Q390B steel sheet can be delivered in hot rolled, controlled rolled, normalized, normalized and tempered, hot mechanical rolled (TMCP) or hot mechanical rolled and tempered state. These different delivery states enable Q390B steel plates to adapt to a variety of different processing processes and application scenarios.

When the steel plate is required to have thickness direction performance, the Q390B steel plate will be added to the symbol Z15, Z25, Z35 representing the thickness direction performance level after the grade. These symbols indicate the level of performance of the steel plate in the direction of thickness, ensuring its reliability and safety in a specific application.

The thickness range of Q390B steel plate is wide, and the thickness range can be produced from 8mm to 700mm, where the material performance is guaranteed to 400mm. The steel plate can also be zero cut according to the need to cut into shaped parts to meet the needs of different projects. The smelting method of Q390B steel plate includes converter or electric furnace smelting, and can be refined outside the furnace if necessary to ensure the purity and uniformity of the steel.

Regarding the size, shape, weight and allowable deviation of Q390B steel plate, they shall comply with the provisions of the corresponding standard GB/T709. This standard specifies the geometric parameters and tolerance range of the steel plate to ensure the consistency and interchangeability of the product.

Q390B steel plate is widely used in power tower, all kinds of lifting cranes, heavy vehicles, oil derrick, high temperature fan, large shovel, dump truck and drilling rig, coal mine hydraulic support, steel structure and other fields. Its excellent performance and reliability make it the material of choice in these fields, providing a solid foundation and guarantee for all types of engineering.

Hot-dip galvanized pipe is a special steel pipe, its surface is covered with a layer of galvanized layer, which is mainly to improve the corrosion resistance of the steel pipe. This steel pipe is mainly divided into two types: hot dip galvanized and electric galvanized. Among them, the coating of hot galvanizing is thicker, and the cost of electric galvanizing is lower, but the surface may not be as smooth as hot galvanizing.

The production process of hot-dip galvanized pipe involves the reaction of molten metal with iron matrix to form an alloy layer. In this way, the substrate and the coating can be tightly bonded together. Specifically, the process of hot dip galvanizing begins with pickling the steel pipe to remove the iron oxide on the surface of the steel pipe. After pickling, the steel pipe is washed in an aqueous solution containing ammonium chloride or zinc chloride before being fed into a hot dip bath. The advantages of hot dip galvanizing lie in its uniform coating, strong adhesion and long service life. In this process, the steel tube matrix and the molten bath will undergo complex physical and chemical reactions to form a corrosion-resistant zinc-iron alloy layer. This alloy layer is closely combined with the pure zinc layer and the steel tube matrix, and therefore has strong corrosion resistance.

In practical applications, the iron pipes commonly used in gas, greenhouses and heating systems are also galvanized. However, when the galvanized pipe is used as a water pipe, a large amount of rust and scale may be produced in the pipe. This will not only contaminate the sanitary ware, but also may breed bacteria because the tube walls are not smooth. In addition, rust may also lead to high levels of heavy metals in water, posing a serious threat to human health. Therefore, from the 1960s and 1970s, developed countries in the world began to develop new pipes and gradually banned the use of galvanized pipes. China's Ministry of Construction and other relevant departments also issued a clear document in 2000, prohibiting the use of galvanized pipes. Now, the cold water pipe in the new community has rarely used galvanized pipe, but the hot water pipe in some communities still uses galvanized pipe.

The hardness of steel is closely related to its internal structure, especially the dislocation in the structure. Dislocation is a kind of microscopic defects in steel, and their existence and movement play a key role in the deformation behavior of steel.

When the steel deformation occurs, it depends on the dislocation slip in the steel to achieve. Dislocation sliding is the process by which a dislocation moves through the crystal structure, resulting in plastic deformation of the steel. However, when the dislocation density is very high, entanglement can occur between the dislocations, and this entanglement can inhibit the movement of the dislocation, resulting in a higher hardness of the steel at the macro level.

Rolling process is an important part of steel processing, it will produce a lot of dislocation in steel. These dislocations become entangled with each other, making the steel more difficult to deform, which leads to an increase in hardness. However, the dislocation is not static, they can cancel each other in the process of thermal motion, resulting in a reduction in dislocation density, so that the steel softening.

Temperature has a significant effect on the behavior of the dislocation. At high temperatures, the dislocations are more likely to cancel each other out, so the softening effect is more pronounced. This is also why the hardness of hot-rolled steel is generally lower than that of cold-rolled steel. However, if the content of alloying elements in the steel is high, and the hot rolling cooling rate is fast, the cooled steel may be transformed into martensite. Martensite is a structure with high strength and hardness, and there are also a lot of dislocations in it, which will make the overall hardness of the steel higher. However, under normal circumstances, hot-rolled steel will inhibit the production of martensite by controlled cooling, so that it will not show higher hardness.

Compared with hot rolling, cold rolling is carried out at a lower temperature, which allows cold rolled steel to obtain better surface quality and dimensional accuracy. However, lower rolling temperatures also greatly increase the rolling stress required during rolling, so the thickness of cold-rolled steel is usually smaller. Hot rolled steel is more suitable for the production of medium and thick plate products.

At the end of cold rolling, the internal stress and hardness are usually reduced by heat treatment. This heat treatment can adjust the structure and properties of the steel so that it meets the required requirements. Therefore, cold rolled steel does not show high hardness.

As for why the cold-rolled plate will make people feel softer, I think it may be because the cold-rolled plate is thinner than the hot-rolled plate, and the structural stiffness is poor, so it appears softer in the feel. But in fact, the hardness difference between cold-rolled and hot-rolled plates mainly depends on their processing technology and internal organizational structure.

Qualified 304 stainless steel is a high-quality material, it should not precipitate heavy metals at any temperature. This means that whether you use this stainless steel product in the cold winter or in the hot summer, there will be no heavy metal ions released into your food or drinking water. However, unqualified stainless steel products may precipitate heavy metal ions in their water under specific conditions, such as acid, alkali and salt. Although temperature has some effect on these processes, the effect is negligible.

Time is the main factor. Therefore, it is not recommended to buy products such as thermos cups and water cups on the ground, because they may not meet the quality standards. In contrast, everyday items such as cutlery, vegetable basins and washbasins can be bought and used with confidence. These items are in contact with water and food for a relatively short time, and most of the dissolved matter or rust is removed during scrubbing. Therefore, their health effects are very weak, and even the amount of heavy metals ingested in a few years is not as much as a plate of stir-fried bracken.

As for the change of 304 stainless steel at different temperatures, it will turn slightly yellow at 150 ° C, significantly yellow at 250 ° C, and seriously yellow at 350 ° C. When the temperature reaches about 400 ° C, the stainless steel will become colored and appear yellow. These problems are not major and are usually caused by the oxidation of iron to iron oxide.

In addition, the color change phenomenon is caused by the formation of oxides of chromium-nickel elements. When you make acidic food with this stainless steel, these oxides may be dissolved and migrate into the food. Therefore, when choosing stainless steel products, it is very important to ensure that they are qualified products that meet the standards.

Basic concepts:

Hot rolling raw material continuous casting slab or blooming slab is used as raw material, heated by stepping furnace, dephosphorized by high pressure water into roughing mill, roughing mill through cutting head, tail, and then into finishing mill, implementing computer-controlled rolling, after the final rolling, laminar cooling (computer-controlled cooling rate) and winding machine to become straight coil. The head and tail of the straight hair curl are often tongue and fishtail, the thickness and width accuracy are poor, and the edge often has defects such as wave shape, fold edge and tower shape. The coil weight is heavy, and the inner diameter of the steel coil is 760mm. (The general pipe industry likes to use.) After finishing lines such as cutting the head, cutting the tail, cutting the edge and straightening and leveling for multiple passes, the straight hair coil is then cut or rerolled to become: hot rolled steel plate, flat hot rolled steel coil, longitudinal cutting strip and other products. Hot rolled finishing coil is formed after pickling and oil coating.

Advantages of hot rolling:

It can destroy the casting structure of the ingot, refine the grain of the steel, and eliminate the defects of the microstructure, so that the steel structure is dense and the mechanical properties are improved. This improvement is mainly reflected in the rolling direction, so that the steel is no longer isotropic to a certain extent; Bubbles, cracks and looseness formed during pouring can also be welded under high temperature and pressure.

Cons:

1. After hot rolling, the non-metallic inclusions (mainly sulfides and oxides, as well as silicates) inside the steel are pressed into sheets, and the phenomenon of lamination (sandwich) appears. Delamination greatly worsens the tensile properties of steel along the thickness direction, and may cause interlayer tearing when the weld is contracted. The local strain induced by weld contraction often reaches several times of the yield point strain, which is much larger than that caused by load.

2. Residual stress caused by uneven cooling. Residual stress is the internal self-equilibrium stress in the absence of external force. Hot-rolled steel of various sections has such residual stress. The larger the section size of general steel, the greater the residual stress. Although the residual stress is self-equilibrium, it still has a certain effect on the performance of steel members under external forces. Such as deformation, stability, anti-fatigue and other aspects may have adverse effects.

Cold rolling with hot rolled steel coil as raw material, after pickling to remove the oxide, cold continuous rolling, the finished product is rolled hard coil, because of the cold hardening caused by continuous cold deformation, the strength and hardness of the rolled hard coil increase, the toughness and plastic index decline, stamping performance deteriorates, can only be used for simple deformation parts. Rolled hard coil can be used as raw material in hot dip galvanizing plant, because hot dip galvanizing units are equipped with annealing lines. The roll weight is generally 6~13.5 tons, and the inner diameter of the steel coil is 610mm. Generally, the cold continuous rolling plate and coil should be deannealed by continuous annealing (CAPL unit) or cover furnace to eliminate the cold hardening and rolling stress, and achieve the mechanical properties specified in the standard. The surface quality, appearance and dimensional accuracy of cold-rolled steel plate are superior to those of hot-rolled plate.

The advantages of cold rolling: fast forming speed, high yield, and no damage to the coating, can be made into a variety of cross section forms to meet the needs of the conditions of use; Cold rolling can produce great plastic deformation of steel, thus increasing the yield point of steel.

Cons:

1. Although there is no hot plastic compression in the molding process, there is still residual stress in the section, which will inevitably affect the overall and local buckling characteristics of the steel;

2. The cold-rolled steel style is generally an open section, which makes the free torsional stiffness of the section low. It is easy to appear torsion when bending, and easy to appear bending and torsional buckling when pressurized, and the torsional resistance is poor;

3. The wall thickness of cold-rolled steel is small, and it is not thickened at the corner of the connection of the plate parts, and the ability to withstand local concentrated load is weak

The main differences are:

1. Local buckling cold rolling is better than hot rolling. The cold-rolled steel allows local buckling of the section, which can make full use of the bearing capacity of the bar after buckling. Hot rolled steel does not allow local buckling of the section.

2, the type of local residual stress is different. The causes of residual stress in hot-rolled steel and cold-rolled steel are different, so the distribution of residual stress on section is also very different. The residual stress distribution on the section of cold-formed thin-wall steel is curved, while the residual stress distribution on the section of hot-tied or welded steel is thin film.

3, anti-torsion hot rolling is better than cold rolling. The free torsional rigidity of hot-rolled steel is higher than that of cold-rolled steel, so the torsional resistance of hot-rolled steel is better than that of cold-rolled steel. 4. In appearance, hot-rolled black, indentation, irregular surface and uneven edge; Cold rolling is the opposite. From the appearance, the surface of cold-rolled steel is smooth, without indentation and oxidation, the color is usually silver-white, the texture is fine and the edge is neat. The surface of hot-rolled steel is rough, there is an oxide skin, the color is darker, such as brown or black brown, and sometimes there is a pattern. The edges may not be as neat as cold rolled steel, and the shape may not be as regular. During the rolling process, the surface of hot-rolled steel is subjected to extremely high pressure and temperature, so indentation with poor toughness may occur.

Hot rolling is a rolling process that is carried out above the recrystallization temperature. Specifically, when a billet is heated to a high enough temperature, it goes through multiple rolling processes. In this process, the steel plate will be cut and straightened, and finally form our common hot-rolled steel plate.

This hot rolling process has significant advantages. First of all, it can effectively reduce energy consumption. Compared with traditional cold rolling, hot rolling has higher plasticity of the metal and lower deformation resistance, which means that the energy consumption required during the metal deformation process is greatly reduced. This not only helps to improve production efficiency, but also reduces production costs, thus bringing greater economic benefits to enterprises.

Secondly, hot rolling can improve the processing properties of metals and alloys. During the hot rolling process, the coarse grains in the cast state will be broken, which helps to heal significant cracks and reduce or eliminate casting defects. At the same time, the as-cast structure will also be transformed into deformed structure, thus improving the machining performance of the alloy. This makes the hot-rolled steel plate have better performance in the subsequent processing and application.

Hot rolling is an important process of high efficiency, energy saving and improving metal working performance. By rolling at high temperature, it can improve metal plasticity and reduce deformation resistance, thus reducing energy consumption and improving production efficiency. At the same time, hot rolling can also improve the processing properties of metals and alloys, providing a better foundation for subsequent processing and application. Therefore, hot rolling plays an indispensable role in the steel industry.

Ordinary medium and thick steel plate: Advantages: smooth surface, good quality, easy processing, relatively low price. Disadvantages: internal bubbles, impurities, bad welding, poor bearing capacity, not suitable for use as parts that need to withstand gravity. General carbon steel sedative steel plate: Advantages: good surface quality, less impurities, uniform force, good welding performance. Disadvantages: More expensive. Low alloy structure steel plate: Advantages: excellent performance, light weight. Disadvantages: More expensive. The advantages and disadvantages of various steels are as follows: ordinary medium and thick steel plate: Advantages: smooth surface, good quality, easy processing, relatively low price. Disadvantages: internal bubbles, impurities, bad welding, poor bearing capacity, not suitable for use as parts that need to withstand gravity. General carbon steel sedative steel plate: Advantages: good surface quality, less impurities, uniform force, good welding performance. Disadvantages: More expensive. Low alloy structure steel plate: Advantages: excellent performance, light weight. Disadvantages: More expensive. Welding structure with weather-resistant steel plate: Advantages: welding performance and weather resistance are very good, and it is widely used in railway, bridge and other areas that need long-term exposure to the atmosphere. Disadvantages: The production process requirements are very high, and the process is slightly poor can not produce a good weather resistant steel plate. Pattern steel plate: Advantages: good decorative performance, anti-slip effect. Disadvantages: The production process is complex, the price is expensive, and the mechanical properties are not high. Welding structure with weather-resistant steel plate: Advantages: welding performance and weather resistance are very good, and it is widely used in railway, bridge and other areas that need long-term exposure to the atmosphere. Disadvantages: The production process requirements are very high, and the process is slightly poor can not produce a good weather resistant steel plate. Pattern steel plate: Advantages: good decorative performance, anti-slip effect. Disadvantages: The production process is complex, the price is expensive, and the mechanical properties are not high.

When galvanized sheet and galvanized steel are used in high temperature environment, the zinc layer on their surface may be spalling phenomenon. This peeling will not only affect the overall appearance of the material, but also may cause certain pollution to the use of the environment. What's more, during the cooking process, if the food comes into direct contact with these peeling zinc layers, the zinc element may react chemically with some of the ingredients in the food.

This reaction may cause changes in the taste, color or nutritional value of the ingredients, and may even produce substances that are harmful to the human body. Therefore, from the point of view of health and safety, galvanized sheet and galvanized steel are not suitable for cooking purposes.

In contrast, stainless steel POTS are a more ideal choice for cooking utensils. Stainless steel POTS are usually chrome plated or porcelain plated surface treatment. Chrome plating can increase the corrosion resistance and wear resistance of the stainless steel pot, so that it can remain bright as new during long-term use. The porcelain plating can not only increase the beauty of the pot, but also further improve its non-stickiness and easy cleaning, so that the cooking process is more convenient and hygienic.

To sum up, although galvanized sheet and galvanized steel have their unique application value in some industrial fields, in the field of cooking, their shortcomings make them not suitable for cooking utensils. The stainless steel pot has become the preferred material in the cooking field because of its excellent performance and safety.

Hot galvanized sheet is hot rolled galvanized sheet, cold galvanized sheet is cold rolled galvanized sheet. From the material point of view, the composition of the two galvanized sheets are basically similar, the difference is that the cold galvanized sheet is thinner than the hot galvanized sheet, the surface quality is better, the process is more complex, and the price is higher. From the process point of view, the steel is rolled by hot rolling, rolled into a certain thickness of the plate, such as the thickness of 10mm or so, if the user has no higher requirements for the surface of the plate, thickness, mechanical strength, it can be processed as a finished product, such as galvanized, sold directly, is a hot plate. If there are higher requirements for the plate, then the hot-rolled plate is sent to the cold rolling line for re-processing, after pickling, annealing, re-rolling and other processes, to get a thinner, smooth surface and better mechanical properties of the cold-rolled plate.

Galvanized strip pipe is a kind of steel pipe made from cold-rolled galvanized strip steel, which is formed by cold bending and then welded by high frequency. It is characterized by strong protective effect and strong corrosion resistance. Let's introduce the production process of galvanized steel pipe.

1. Feeding process

The first process is the feeding process, the galvanized strip is fixed on the material rack; Convenient to put the strip steel into the storage box for the unit to use, our company spent a lot of money to build MES system, above the production information, production information, warehousing information. Realize paperless office, information sinks to every process, so that employees have first-hand information in real time. Raw materials enter the storage box to ensure continuous operation of the unit.

2. The second process of forming welding zinc supplement process is forming welding zinc supplement process. The strip steel is transformed into steel pipe by forming roll. Next up is the welding and scab removal process. We adopt the more advanced ERW welding process in China, the main principle is to use the skin effect and proximity effect of high-frequency welding, so that the surface metal of the weldment to be welded can be heated quickly to achieve welding. Its advantage is that the heat affected zone of the weld is small, the heating speed is fast, and the welding speed and quality are improved. This process plays a key role in the corrosion resistance of the weld of the steel pipe. We use 2 zinc wires with a diameter of 1.5mm and a zinc content of 99.99% to replenish the weld with zinc to ensure the corrosion resistance of the weld to the maximum extent. With this process, we can ensure that the weld is completely invisible on the outside of the steel pipe, and the corrosion resistance of the weld after our treatment is completely consistent with the other parts of the steel pipe.

3. Set the straight process

The third process is the sizing and straightening process, the adjustment of the welded billet shaping roller can ensure the outer diameter accuracy of the steel pipe, or the round pipe is changed into a square tube, and the straightening roller can ensure the straightness of the steel pipe.

4. Flying saw sawing process

The fourth process is the sawing process, when the length meets the parameter requirements, the flying saw will automatically cut, we use the latest generation of high-speed flying saw, cutting speed can reach 150 meters -180 meters/minute; To ensure that the pipe end interface is more flat to the maximum extent, more convenient for later end customers to use.

5. The fifth process of weld inspection process is the weld inspection process. Our product quality control is quite strict. The staff will single out the unqualified products, and we will downgrade the unqualified products.

6. Inkjet marking process

The sixth process is the inkjet printing process, our company uses France's more advanced inkjet machine, which is characterized by clear inkjet, not easy to fade. Our product brand name, slogan and product implementation standards are printed on each steel pipe to ensure that each steel pipe can be reflected.

7. Passivation process

The seventh process is passivation process, in the passivation process we have our own invention patent - galvanized pipe passivation liquid automatic spraying system, to ensure that the passivation liquid 360° uniform adhesion, high passivation efficiency, beautiful outside. Can meet the salt spray test for at least 18 hours, no corrosion. Exclusive process, anticorrosive and durable.

8. The eighth process of automatic blanking packaging process is the automatic blanking system of steel pipe, which is the highest application of our automation and intelligent program. The robot arm is turned over to the conveyor chain, and the protected conveyor chain transmits the steel pipe to the material of the stepper machine for step loading. The automatic sensor is used to identify the position of the steel pipe, the system collects signals, controls the reciprocating transport of the steel pipe by the stepper, and aligns the steel pipe by the roller table. The automatic coding machine automatically identifies the number of steel pipes according to the input instructions, and uses the electromagnetic device to pick up, translate, place and reset the steel pipes in one go to realize the automatic place. The whole process does not require manual operation, and workers only need to monitor the system to work correctly.

9. Automatic weighing and labeling process after packaging, the steel pipe is stepped to the weighing machine by the conveyor chain, and automatically lifted and weighed, automatically labeled, automatically pasted, and automatically discharged from the warehouse in one go. Greatly reduce the labor intensity of employees, but also to ensure that the weight of each steel pipe is accurate, and each steel pipe information (product specifications, production date, raw material manufacturers, production teams, each piece of weight) are given an independent two-dimensional code, easy to trace.

Galvanized pipe (SC) is a common steel pipe material, which is treated by hot-dip galvanizing technology in the manufacturing process. So, what does galvanized pipe SC mean?

1. Basic concept of galvanized pipe

Galvanized pipe refers to the pipe immersed in molten zinc liquid, after a series of chemical reactions and physical changes, so that the surface of the pipe formed a layer of zinc-iron alloy coating of the pipe. This galvanized treatment can effectively prevent the corrosion of the surface of the steel pipe and extend the service life of the steel pipe.

2. Meaning of galvanized pipe SC

The "SC" in galvanized pipe SC stands for "Standard Class". In the production and sales process of galvanized pipes, in order to facilitate the distinction between different standards and specifications, some code names or abbreviations are often used to indicate.

3. Standard grade of galvanized pipe SC

The standard grade of galvanized pipe is differentiated according to its manufacturing process and material and other factors. Generally, galvanized pipe SC is divided into SC1, SC2 and SC3 grades, which correspond to different surface treatment quality and corrosion resistance.

SC1: The surface treatment quality is higher, the galvanized layer is thicker, and the corrosion resistance is better. Suitable for demanding engineering projects, such as chemical, oil, natural gas and other fields.

SC2: Moderate surface treatment quality, moderate galvanized layer, good corrosion resistance. Suitable for general engineering projects, such as buildings, Bridges, roads and other fields.

SC3: The surface treatment quality is low, the galvanized layer is thin, and the corrosion resistance is general. It is suitable for some projects with low requirements for galvanized layer, such as agriculture, furniture and other fields.

4. Application field of galvanized pipe SC

Galvanized pipes are widely used in various fields, including construction, industry, agriculture and so on. It has the following main features:

- Good corrosion resistance: the galvanized layer can effectively prevent the surface of the steel pipe from oxidation and corrosion, and improve the service life of the steel pipe.

- Good welding performance: the galvanized pipe can maintain good welding performance during the welding process, and it is not easy to have weld cracking and other problems.

- Wide applicability: Galvanized pipe can be applied to different engineering projects and environmental conditions, with strong adaptability.

- Low cost, easy processing: Galvanized pipe manufacturing cost is relatively low, processing and installation is convenient, suitable for large-scale production and use.

In the construction field, galvanized pipes are often used in the construction of water supply pipes, drainage pipes, HVAC pipes and other systems. In the industrial field, galvanized pipes are often used for conveying gas, liquid and other media pipeline systems. In the field of agriculture, galvanized pipes are often used to build greenhouses and build livestock facilities.

Hot-plated pipe and ordinary galvanized pipe, although the two seem similar, but there are significant differences. These differences are mainly reflected in their production processes, performance characteristics and application fields.

First of all, from the point of view of the production process, the hot-plated tube is produced by the hot-dip galvanizing process. In this process, the steel pipe first goes through a pre-treatment process such as pickling and cleaning, and then is immersed in the molten zinc liquid, and is removed after a period of time to form a zinc-iron alloy layer. The ordinary galvanized pipe is produced by electroplating process, that is, zinc ions are deposited on the surface of the steel pipe through the action of current to form a zinc layer. These two different production processes make the performance of hot-plated pipe and ordinary galvanized pipe different.

In terms of performance characteristics, because of the hot dip galvanizing process, the zinc-iron alloy layer on the surface of the hot plated tube is closely combined with the steel tube matrix, which has good corrosion resistance and can effectively prevent the corrosion of the steel tube during use. The zinc layer of ordinary galvanized pipe is relatively thin, the binding force with the steel pipe matrix is weak, and the zinc layer is easy to fall off during use, which affects its anti-corrosion performance.

In addition, in the field of application, because of its excellent anti-corrosion performance and long service life, hot plated tubes are widely used in various fields such as construction, transportation, petroleum, chemical industry, especially those with high anti-corrosion performance requirements. The ordinary galvanized pipe is mainly used for some occasions with low anti-corrosion performance requirements, such as some temporary buildings or facilities.

In general, hot plated pipe and ordinary galvanized pipe are a kind of galvanized steel pipe, but due to the different production process and performance characteristics, they are also different in the application field. When choosing the use, we need to choose the appropriate type of steel pipe according to the specific use environment and needs.

1. Different references

1. cold binding plate: hot rolled coil as raw material, at room temperature under the recrystallization temperature to stop rolling products.

2. galvanized plate: refers to the appearance of a layer of zinc plated steel plate.

Second. different characteristics

1. cold binding plate: because it does not stop heating, there is no pitting and oxide sheet defects that are often presented in hot rolling, and the appearance is good and the brightness is high. Moreover, the dimensional accuracy of cold-rolled products is high, and the performance and organization of products can meet some special application requirements, such as electromagnetic properties and deep drawing properties.

2. galvanized sheet: Galvanized sheet due to the different treatment methods in the plating process, the appearance of the state is different, such as ordinary zinc flowers, fine zinc flowers, flat zinc flowers, zinc flowers and phosphating treatment appearance. The German code also rules for appearance levels.

Three. different uses

1. cold tie plate: mostly used in automobile manufacturing, electrical products and so on.

2. Galvanized sheet: mainly used in construction, light industry, automobile, agriculture, animal husbandry, fishery and commercial industries. The construction industry is mainly used for the manufacture of anti-corrosion industrial and civil building roof panels, roof grilles, etc. The light industry uses it to manufacture home appliance housings, civil chimneys, kitchen utensils and so on.

"Galvanized sheet 275g/㎡" means that the sum of the double-sided galvanized amount of the galvanized sheet per square meter area is 275 grams. The zinc flowers of hot dip galvanized steel plate are larger and more obvious, called "zinc flowers", and the zinc flowers are not fine enough, called "no zinc flowers".

What does having flowers and no flowers mean which is more expensive?

The zinc flowers of hot dip galvanized steel plate are larger and more obvious, called "zinc flowers", and the zinc flowers are finer and less obvious, called "no zinc flowers".

The hot plate substrate is generally made of zinc flowers, the cold plate substrate is generally made of no zinc flowers, and the cold plate is made of no zinc flowers, the surface is more smooth and smooth, the hardness is low, the elongation is high, the directional consistency is good, and the price is more expensive.

Galvanized sheet flowers and flowers are differentiated according to the surface state of galvanized sheet, generally weak eye will know, the surface has a pattern is flowers, there is no flowers. Flowers and no flowers have nothing to do with the material. The material depends on the substrate used for galvanizing, such as Q195, Q345, SPCC and so on. There is also no relationship between thickness and presence of zinc flowers.

There is a galvanized sheet, that is, the surface of the galvanized sheet is printed with a pattern, the appearance looks very bright, beautiful, and is generally used to make home appliance shells, buckets, and so on. There is no pattern on the surface of the flowerless galvanized sheet, which looks not as bright as the flowered galvanized sheet, dark color, and cold plate. There is no difference in performance, mainly in appearance.

There is a flower is the surface of the board has a pattern like a leaf, but also divided into small zinc flowers with large zinc flowers, no flowers is like aluminum plate, flat what pattern is not there

The main materials of Marine steel plates are carbon steel and alloy steel.

First, carbon steel ship plate

Carbon steel mainly refers to ordinary steel with carbon content between 0.05-2.0%. Carbon steel ship plate is widely used in various types of ships, which is characterized by high strength, good toughness, good weldability and low cost. In addition, the reliability of carbon steel materials is high and can withstand strong hot and cold deformation, which is necessary for Marine steel plates.

The main disadvantage of carbon steel ship plates is that they are susceptible to corrosion by seawater and air, so special anti-corrosion treatment is required, including painting and the use of anti-rust coatings. At the same time, the service life of the carbon steel ship plate is also relatively short, and it needs to be replaced frequently.

Second, alloy steel ship plate

Compared with carbon steel, alloy steel ship plate has lower carbon content and adds a certain proportion of alloying elements, such as manganese, silicon, chromium, tungsten, molybdenum, etc., to increase the strength and corrosion resistance of steel. Alloy steel ship plates are more resistant to corrosion and last longer than carbon steel ship plates.

Alloy steel ship plate has the following characteristics:

1. High strength: The addition of alloying elements can improve the strength of steel and enhance the carrying capacity.

2. Good corrosion resistance: the alloy elements such as chromium not only increase the strength of the steel, but also form a dense chromium oxide film, which can prevent further corrosion.

3. Good cold working performance: compared with ordinary steel, alloy steel can better withstand strong hot and cold deformation, and it is not easy to produce surface cracking, fracture and other phenomena.

The choice of Marine steel plate material depends on many factors such as the ship's use environment, transportation volume and economic cost. Factors such as physical and chemical properties, corrosion resistance, cost and processing difficulty need to be considered when selecting materials.

The interaction between magnets and galvanized steel is a topic that involves materials science and the principles of magnetism. First of all, we need to understand that the reason why magnets can adsorb certain metals is because these metals are magnetic, or they can be magnetized and attracted to magnets. However, as a non-magnetic metal, zinc does not attract magnets.

Galvanized steel is a special kind of steel whose manufacturing process involves plating a layer of zinc on the surface of ordinary steel. This process is usually done by hot dip galvanizing, in which the steel is dipped into a molten zinc solution that adheres to the steel surface and forms a protective layer. The main function of this layer of zinc is to provide anti-corrosion function and protect the steel from the external environment, thus significantly extending the service life of the steel.

Because zinc is a non-magnetic material, when the magnet is near the galvanized steel, the galvanized layer itself will not be attractive to the magnet. This means that if only the galvanized layer is considered, the magnet will not adhere to the galvanized steel. The reality, however, may be more complicated. If the substrate beneath the galvanized layer is magnetic steel, and the zinc layer is not thick enough to completely isolate the magnetic force between the magnet and the substrate, then the magnet may "stick" to the galvanized steel in this indirect way. This is because the magnet attracts the magnetic part of the substrate, which generates enough force to keep the magnet on the galvanized steel surface.

In the plating process, in order to improve the performance and appearance of galvanized steel, other surface treatment techniques may be used. For example, some galvanized steel may be further treated and covered with a black protective film, which not only provides additional anti-corrosion effect, but also improves the appearance of the product. However, this protective film is also usually non-magnetic, so it also does not affect the adsorption capacity of the magnet.

Whether the magnet will stick to the galvanized steel mainly depends on two factors: first, whether the steel under the galvanized layer is magnetic, and second, whether the thickness of the zinc layer is sufficient to prevent direct contact between the magnet and the magnetic substrate. If these two conditions are met, then it is possible for the magnet to be indirectly adsorbed on the galvanized steel through the magnetic substrate. On the contrary, if the galvanized layer is thick enough, or the substrate itself is not magnetic, then the magnet will not stick to the galvanized steel

The effect of sound absorption and noise reduction is closely related to the shape and size of the room and the location of the sound absorption material. Together, these factors determine how sound is transmitted in the space, which affects the performance of the sound-absorbing board.

First of all, when the area of the room is large, if people's activity area is close to the sound source, then the direct sound will dominate. Direct sound refers to the sound that is transmitted directly from the sound source to the receiving point without any reflection and scattering. In this case, the role of the sound absorption board is relatively small, because it mainly affects the reflected sound, and the proportion of direct sound is high, and the improvement of the sound absorption board on the overall sound environment is limited.

On the contrary, if the area of the room is small, the sound emitted by the sound source will be reflected many times between the various walls, and the direct sound will be mixed together to form a complex sound field. In such an environment, the role of the sound absorption board is particularly important. The sound absorption board absorbs part of the reflected sound, reducing the energy of the sound, which significantly reduces noise levels and improves sound clarity.

In addition, the shape of the room will also have an impact on the sound absorption effect. For example, if a room has a lanky shape and is more than five times as long as it is wide, sound will experience more reflection in such a space. In such a space, the sound absorption board can effectively capture the sound of multiple reflections, reducing the number of reflections of the sound, thereby improving the sound absorption effect.

To sum up, in order to achieve the best sound absorption and noise reduction effect, it is necessary to consider not only the performance of the sound absorption material itself, but also the size, shape and layout of the room. Through careful planning and design of these factors, the quality of the indoor acoustic environment can be significantly improved, creating a more peaceful and comfortable listening space.

There are four types of primer and film thickness primer: epoxy resin, polyester resin, acrylic resin and polyurethane resin. The primer is generally selected according to the bottom use of the product, the occasion of use, the degree of processing, and the matching of the top paint. The film thickness of the primer is usually 5um.

1. epoxy primer

It has good adhesion to the substrate, good water resistance, alkali resistance and chemical corrosion resistance, and is the earliest coil primer, and its flexibility is not as good as other primers.

2. polyester bottom

Good adhesion with the substrate, excellent flexibility, more sensitive to wet environment, chemical resistance is not as good as epoxy primer.

3. water-soluble acrylic primer

Good adhesion to the substrate, excellent flexibility, organic solvent content bottom, low temperature curing, not suitable for storage in a humid environment, high requirements for pretreatment.

4. polyurethane primer

It has chemical resistance, friction resistance, durability and good flexibility.

Type of finish and film thickness

The most commonly used topcoats are polyester, silicon modified polyester, polyvinyl chloride plastisol and polyvinylidene fluoride.

1) Polyester

Good adhesion, wide range of formability and outdoor durability, moderate chemical resistance.

2) silicon modified polyester

The hardness, wear resistance and heat resistance of the coating film are good, as well as good outdoor durability and non-powdering, gloss retention and flexibility are limited, and the cost is medium to high.

3) polyvinylidene chloride

With good formability and color retention, excellent outdoor durability and resistance to powder, solvent resistance, limited color, expensive.

4) polyvinyl chloride plastic sol

Excellent external durability and chemical resistance, damage resistance, beautiful, need special primer matching. The surface can have a smooth type for compression or automatic shrinkage type to form a pattern. The coating thickness is generally greater than 100um, in addition to plastisol, under normal circumstances, the coating thickness of the primer and top paint &gt; =20um, the performance of its products can achieve the predetermined purpose.