Stainless Steel 304/316L/321 Difference

Stainless steel 304 316L 321 difference

When it comes to the difference between stainless steel, you must first understand the characteristics of each common stainless steel. 201 stainless steel is the most cost-effective stainless steel material, the price is cheap, but easy to rust; 304 stainless steel is the most common and most widely used stainless steel material, not easy to rust, good quality, the price is relatively high; 316 stainless steel is an imported material, used in some high-end equipment, such as aerospace, food machinery and other fields, the price is high.

304 and 316 stainless steel difference

In fact, with the naked eye can not see the difference between 304 and 316 stainless steel, many people see these figures are confused, today with me to look at the difference between 304 and 316 stainless steel.

First of all, 316 stainless steel contains Mo, which is better corrosion resistance than 304 stainless steel in high temperature environments, so in high temperature environments, engineers generally choose parts of 316 materials.

Secondly, there are also differences between the two from the brand; 304 stainless steel corresponding to the Chinese brand 0Cr18Ni9; 316 stainless steel corresponding to the Chinese grade 0Cr17Ni12Mo2.

Third, 316 mainly reduces Cr content, increases Ni content and increases Mo2%~3%. Thus, its corrosion resistance is stronger than 304, suitable for use in chemical, seawater and other environments, similarly, 316 cost is higher than 304, 316 is generally used in places with higher requirements, to replace 304.

304 and 321 stainless steel difference

The main difference between 304 and 321 stainless steel is that 304 does not contain Ti, 321 contains Ti, Ti can prevent stainless steel sensitization, popular is to improve the high temperature service life of stainless steel, that is, in a high temperature environment, 321 stainless steel plate is more suitable than 304 stainless steel plate. Both 304 and 321 are austenitic stainless steels with very similar appearance and physical properties, except for slight differences in chemical composition.

First of all, 321 stainless steel is required to contain a trace amount of titanium (Ti) element (according to ASTM A182-2008 standard provisions of its Ti content should not be less than 5 times the carbon (C) content, but not less than 0.7%, note that 304 and 321 carbon (C) content is 0.08%), and 304 does not contain titanium (Ti).

Second, the requirements for nickel (Ni) content are slightly different, with 304 being between 8% and 11%, while 321 is between 9% and 12%.

Third, the requirement for chromium (Cr) content is different, 304 is between 18% and 20%, while 321 is between 17% and 19%.

So you can use metal analyzer or chemical analysis methods to test the composition of these two materials and judge.