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304 VS 316 & L Meaning

In our daily life, the mugs we use, the spoons and forks we use, and the medical equipment we use all have one common characteristic — they are made of stainless steel, which can be 304 stainless steel, 316 stainless steel, or 304L or 316L. Stainless steel. Do you know the difference between these materials?


The difference between 304 and 316 materials

The density of 304 stainless steel is 7.93 g/㎝³, and the density of 316 stainless steel is 8.03 g/㎝³.

There is no apparent difference between the two, and both are a kind of many stainless steel grades, which have the characteristics of acid resistance, alkali resistance, easy processing, and high toughness.

But if you divide it deeply, you can see the difference between these two materials: 304 is mainly used for the production of pots and pans and other home decoration products, and it is also a relatively simple material category, while 316 adds the elements Ni, Cr, Mo to 304, and 316 have higher density, corrosion resistance and high-temperature resistance than 304, which is why they are widely used in various industries (seawater equipment, chemical, dyes, papermaking, oxalic acid, fertilizer, etc..) Equipment).

For people like us, we may not pay too much attention to the difference in the chemical sense. What we pay more attention to when buying is: spending 316 money to buy 304 products (lost) or 304 money to buy something made with 304 (reasonable).

The difference between the two is not much different, but many companies still use 304 as 316 for sale. It is impossible to distinguish the two with the naked eye. The easiest method is to identify by element class: the corresponding name of 304 stainless steel is 06Cr19Ni10, while the 316 stainless steel is OCr17Ni12Mo2. If no name is identified on the product description label, it can only be identified by professional methods.

Is food grade 304 the same as 304?

On the introduction page of the product details, we often see this adjective: This product is made of 304 food-grade stainless steel, which can be used confidently.

Therefore, everyone naturally thinks that food-grade stainless steel is 304 stainless steel. This view is wrong. The quality determines the corrosion resistance of stainless steel. Still, the precipitation index of five heavy metals such as lead, chromium, nickel, cadmium, and arsenic determines whether it is food grade.

What does the “L” in 304L mean?

The “L” here mainly refers to the carbide content in the stainless steel. The stainless steel with “L” in the grade reduces the carbide content by human intervention. It is mainly used in high precision and high-risk industries, which is helpful for more stable operations. High-temperature welding process; otherwise, there is no difference between 304 and 304L, 316 and 316L.


Will 304/316 also rust?

Of course.

When the chromium content reaches a certain percentage, the corrosion resistance of the steel changes abruptly, and a solid protective film forms on the surface, which does not rust easily. When this protective film is destroyed, the stainless steel rusts.

Moisture in the environment and too much bleaching powder stimulate this protective film and cause the stainless steel to rust.

All in all, for products of daily life, 304 is enough