Application field of stainless steel corrosion medium condition of pickling process

From the analysis of stainless steel coil application industry, the automotive industry is the fastest growing stainless steel coil application field. In the past decade, the consumption of stainless steel coil plates for automobiles in Japan has increased from an average of 10 kg to 30 kg, and the United States has exceeded 40 kg. Buses, subways, high-speed railway vehicles and other public transport vehicles are also widely used in stainless steel coil. China's home appliance industry is a potential big market for stainless steel coil applications. In addition, the demand for stainless steel coils in the water industry, construction and structure industry, environmental protection industry, and industrial facilities will also rise year by year.

I. Vehicle/automobile industry

This is currently the fastest growing stainless steel coil application field. The use of high-strength stainless steel coil to manufacture the car body structure can greatly reduce the weight of the vehicle, enhance the strength of the car body structure, and use stainless steel coil as the vehicle panel and decorative parts can reduce maintenance costs. In addition, stainless steel coils are also used in automotive exhaust systems because of their advantages of chloride ion corrosion resistance and heat resistance.

2. Water industry

The pollution of water in the process of storage and transportation has been paid more and more attention. A large number of practices have proved that stainless steel coil is the best material for water industry such as water preparation, storage, transportation, purification, regeneration and seawater desalination. Its advantages are: corrosion resistance, earthquake resistance, water saving, health (no rust and copper green), light weight (reduced by 1/3), less maintenance, long life (can be used for 40 years), low life cycle cost (LCC), is a recyclable green material. According to reports, at present, the stainless steel coil of pipelines in Tokyo, Japan, has reached 76%, and the pipeline leakage rate has dropped from the original 14.7% to the current 7.5%. Stainless steel coil water storage tanks remain intact after a massive earthquake hit Osaka, Japan. Recently, Japan developed a corrugated pipe joint, so that the construction cost of stainless steel coil water pipeline is reduced by 20%, the total cost is reduced by 3%, and the maintenance cost is reduced by 3/ Foshan Stainless steel 4.

Iii. Construction Industry

It is one of the earliest applications of stainless steel coil. In terms of architectural decoration, at present, stainless steel coil is mainly used in the exterior wall, interior and outer column cladding of high-rise buildings, handrails, floors, elevator panels, doors and Windows, curtain walls and other internal and external decoration and components. After surface treatment, coloring, coating of stainless steel coil plate, solve the problem of easy to appear after touch, so that the application range of stainless steel coil further expanded. Japan has developed a variety of stainless steel sheet roofing materials, such as high and medium chromium ferrite with better corrosion resistance and various coated plates. The super-clean brushed stainless steel roll plate developed by Sweden and the UGITOP surface plate developed by Ugine in France provide a new choice for the construction industry.

In the stainless steel pickling process, each section has different corrosive media, and the pickling medium provided by a steel company is as follows:

1. the original acid

Sulfuric acid: the liquid concentration in the tank is 150 ~ 300g/L, the temperature is < 90℃, concentration 9 Foshan stainless steel 8%;

Nitric acid: the liquid concentration in the tank is 100 ~ 200g/L, and the temperature is < 90℃, 65% concentration;

Hydrofluoric acid: the liquid concentration in the tank is 40 ~ 60g/L, the temperature is < 65℃, the concentration of the original solution is 70%.

2. Mix the acid

Nitric acid and hydrofluoric acid: the liquid concentration in the tank is 40 ~ 60g/L, and the temperature is < 65 ° C.

3. Waste water

Acidic wastewater containing heavy metal ions, salts and fluoride ions.

4. Exhaust gas

Exhaust gas containing HF and NO×.

It can be seen from the above medium conditions that the corrosion of the medium is very strong, especially the concentration and temperature of sulfuric acid and nitric acid are relatively high, and they have strong oxidation. China Epoxy Resin Industry Association experts stressed that, therefore, in the pickling process medium storage and use of media equipment for anti-corrosion materials are very high requirements.

According to the different corrosive media in the above sections, the equipment and the ground in different sections need different anti-corrosion treatment, and the experts summarized the specific anti-corrosion methods.