Is 304 stainless steel divided into food grade and non-food grade?

Stainless steel, which seems to be ordinary but contains infinite possibilities, plays a distant and close role in our lives. It is far away, because we can often see its real figure in the grand industrial scene: the huge volume of products, like the backbone of the iron and steel dragon, carrying the strength and brilliance of industry; The long steel pipes, like the blood vessels of the city, connect every corner and support the skeleton of tall buildings; The broad and thick steel plate is the cornerstone of industrial civilization, and they are tenacious and guard countless engineering miracles.

However, stainless steel is so close to our daily life that it is almost within reach. Whenever we pick up a cup of spring, the water cup may be made of stainless steel, it quietly accompanies us, quenches our thirst for heat; When we prepare a delicious meal, the sharp knives and forks, the delicate tableware, and the POTS and pans used for cooking may be made of stainless steel. These stainless steel products, with its durable, beautiful, easy to clean characteristics, have become an indispensable part of our daily life.

When buying these everyday items, we naturally put health and safety first. After all, these items will come into direct contact with our food and even become "regulars" on our tables. Therefore, we pay special attention to whether they are made of food grade stainless steel. Food grade stainless steel, the word sounds reassuring and reassuring. It means that the content of harmful substances in the production process of these stainless steel products is strictly controlled to ensure that it will not pollute our food during use.

However, although food-grade stainless steel has built a solid defense line for our health, we still need to be vigilant about possible safety risks. The main safety problem of stainless steel for food contact is the amount of heavy metal migration. Although under normal conditions of use, the amount of migration of these heavy metals is very small, almost no harm to the human body. But once we do not pay attention to maintenance or improper use in the use process, resulting in excessive migration of heavy metals, then these originally harmless stainless steel products may become a health "invisible killer".

Fortunately, as long as we have the right use and maintenance skills, we can effectively avoid this risk. For example, when using stainless steel tableware, acidic or alkaline foods should be avoided for a long time to avoid accelerating the migration of heavy metals; When cleaning stainless steel products, mild detergents and soft cloths should also be selected for wiping to avoid scratching the surface leading to exposure to heavy metals. In this way, we can ensure that these stainless steel products bring us convenience, but also protect our health and safety.

The dietary salt we frequently contact and use in our daily diet, its main component chloride ions, has a very significant impact on the amount of heavy metal migration in stainless steel. When we contact the food salt containing chloride ions with stainless steel products, chloride ions will accelerate the phenomenon of point corrosion on the surface of stainless steel with a subtle and complex chemical mechanism. This point corrosion is not evenly distributed throughout the stainless steel surface, but will form corrosion holes in some specific small areas, that is, the so-called pitting holes. These holes are like a "channel", so that the heavy metal ions that originally existed in the interior of stainless steel have a way to precipitate, so as to enter the food we eat or the liquid in contact with.

Take the POTS and pans and other tableware that we use every day in our daily lives, for example, they are often soaked in water during use. For example, when we clean tableware, in order to make it cleaner, we often let them soak in water for a period of time, and sometimes we even forget to take them out in time because we are busy, making the soaking time too long. In addition, during the cooking process, these tableware will also be subjected to high temperatures. Whether it is directly heated on the stove, or heated in the oven, microwave oven and other appliances, high temperature will have a certain impact on stainless steel tableware. Under the combined effect of these factors, the possibility of heavy metal ions migrating out of stainless steel will be greatly increased.

Therefore, when we buy tableware, it is particularly important to choose those stainless steel tableware with high temperature resistance and good corrosion resistance. When it comes to food-grade stainless steel, don't think that only 304 stainless steel is oh. In fact, there are mainly 430 stainless steel, 304 stainless steel and 316 stainless steel types of food grade stainless steel, and the later its price is usually higher.

Let's start with 430 stainless steel, which belongs to the 400 series stainless iron. Because it does not contain nickel in its chemical composition, it is inferior to 300 series stainless steel in terms of corrosion resistance. If it is used to make the pot body, it is obviously not suitable. Because in the cooking process, the pot will be exposed to various ingredients and seasonings for a long time, coupled with the role of high temperature, 430 stainless steel may not be well resistant to corrosion, resulting in an increased risk of heavy metal ion migration. However, it can still be used to make pot LIDS. And ah, 430 stainless steel has a very outstanding advantage, that is, its magnetic conductivity is very good. This feature makes it perform well in the use of induction cooker scenarios, can be well induced and heated by the magnetic field of induction cooker, and is a good choice for making special induction cooker POTS. In addition, because of its high hardness and good wear resistance, it is often used to make tools and other products that require wear resistance and hardness.

Let's talk about 304 stainless steel that we can often see in our daily life. It contains more than 8% nickel, so it is also known as 18-8 stainless steel. In the field of food, its application is very wide, like our commonly used POTS and pans, tableware, kettles and many other are made of 304 stainless steel. However, it is important to note that not all 304 stainless steel can be called food-grade stainless steel. Only those 304 stainless steel produced in strict accordance with the national GB9684-2011 standard can be identified as food-grade stainless steel. In addition, 304 stainless steel will also be used for some industrial purposes, that is, non-food grade application scenarios. In these non-food grade use scenarios, because the requirements for materials are not as strict as in the food field, there may be some potential risks, such as excessive heavy metal ion migration.

Finally, let's talk about 316 stainless steel. It is also occasionally used in the production of food-grade stainless steel, which is relatively high-end and the price is relatively high. Its nickel content is more than 10%, so it is also known as 18-10 stainless steel. 316 stainless steel is not only excellent in terms of corrosion resistance, but also highly recognized in terms of safety. It is often used in the medical field, such as some medical devices, surgical instruments and other products that require high safety and stability of materials will use 316 stainless steel. It can be seen that the performance of 316 stainless steel in terms of safety is conceivable.

When we buy regular goods, we will find that the surface and inner wall of these products will be clearly marked with the "food grade stainless steel" logo. Among the many products with food grade labeling, those labeled "food grade - GB9684" products will be more secure in terms of safety because they are produced in strict accordance with relevant national standards. I hope that everyone can polish their eyes whe