Common stainless steel in life, what is the difference between 304, 304L, 316, 3
Posted by hifactory on May 12th, 2020
304, 304L, 316, 316L, these are called "brands" of stainless steel. Different grades of stainless steel have different proportions of substances contained in them-the metal properties are also different.
I would like to answer the question in this topic in two parts: the difference between "L" and "L" in the grade; the difference between 304 stainless steel and 316 stainless steel.
Also See: Stainless Steel, Intergranular Corrosion, 304 Stainless, 316 Stainless, Steel, Stainless, Corrosion
"L" in the grade
First of all, we have to understand a term called "intergranular corrosion". Refers to the precipitation of carbides during the welding of metals at high temperatures.
After the precipitation of carbides, it will affect the stability of the welding-more terrible is that the intergranular corrosion can not be distinguished from the appearance.
In other words, after welding of ordinary metals, the welding may be weak due to the existence of intergranular corrosion. And this kind of infirmity can only be seen after the external force causes the welding to break-it is only found after breaking, it is a bit too late!
In order to prevent the occurrence of intergranular corrosion, we must reprocess ordinary metals-that is, reduce the content of carbides in the metal. If the content is less, it is naturally not easy to precipitate due to heat.
This kind of metal with reduced carbide content will be added with an "L" after the brand name-304 stainless steel, which is the product of 304 stainless steel after carbide reduction, in addition to preventing intergranular corrosion, the performance is the same as 304 stainless steel Same; 316L stainless steel is the same.
Metals with reduced carbides are more resistant to high temperatures, not only for metals used in some ultra-high temperature environments when welding but also need to use "L".
The difference between 304 and 316
The full name of "stainless steel" in our colloquial is called "stainless acid-resistant steel"-it is not only rust-proof but also resistant to acid and alkali corrosion. All stainless steels are not rusty, but their ability to resist corrosion and mechanical strength is different-according to this ability, they are divided into different brands, 304 stainless steel and 316 stainless steel are two of them.
The corrosion resistance of 304 stainless steel is already very strong. Almost everything you see in daily life is hard to get it. Because of this, 304 stainless steel has been designated as "food-grade stainless steel" by the national standard.
The corrosion resistance of 316 stainless steel is even stronger. In addition to oil, salt, sauce and vinegar tea, it can resist all kinds of strong acids and alkalis. Not only that, but 316 stainless steel also has lower environmental requirements-too high or too low temperature will not affect the corrosion resistance of 316 stainless steel.