Tips for buying stainless steel: How to accurately identify the type of stainless steel?
Some people think that "stainless steel will not rust." This understanding is not correct. The "stainless" of stainless steel does not mean that it will not rust at all, but that it is relatively difficult to rust under certain conditions. If the user uses it improperly or the use environment exceeds its corrosion resistance range, it will also rust.
304 stainless steel products are harmless and risk-free, and are the first choice for consumption. However, how to ensure that the stainless steel purchased is made of 304 stainless steel? There is a phenomenon of manufacturing and selling low-quality stainless steel products in the market. When buying stainless steel products, how to quickly identify these frauds? Is there a simple way?
Physical identification refers to the use of simple utensils to determine whether it is stainless steel or a specific type of stainless steel based on the physical and chemical properties of the product itself when the steel type (steel type) is unknown.
It should be noted that physical identification methods are difficult to accurately distinguish specific steel types. For example, only three categories of stainless steel, nickel, and manganese nitrogen stainless steel can be distinguished. Here are some identification methods:
Color identification
The surface of stainless steel is white and bright after pickling. Chromium-nickel stainless steel is silvery white and has a jade-like luster, slightly gray and shiny, and slightly lighter in color than chromium-nickel stainless steel. The surface color of chromium-manganese-nitrogen stainless steel is brown-white when it is not pickled, chromium-manganese-nitrogen stainless steel is black, and chromium stainless steel is brown-black.
Magnet identification
Magnets can distinguish the two types of stainless steel. Because chromium stainless steel will be attracted by magnets under any circumstances. While nickel stainless steel is usually non-magnetic in the annealed state, it may be magnetic after cold working. However, although magnets can distinguish chromium stainless steel from chromium-nickel stainless steel, they cannot accurately judge some special-purpose steels, such as SS410 and SS316.
Copper sulfate identification
After removing the oxide layer on the surface of the steel, drop a drop of water and wipe it with copper sulfate. If the surface of the steel does not change color, it is mainly stainless steel. If it turns purple, it is non-magnetic steel, that is, high manganese steel. This also means that magnetic steel is mostly ordinary steel or low-alloy steel.
Grinding identification
Grinding refers to grinding stainless steel on a grinder and observing sparks. If the sparks are streamlined and have dense nodules, it is high manganese steel or manganese-nitrogen steel with a higher manganese content. If there are no nodules, it is chrome steel or chrome-nickel stainless steel.
There are also many ways to identify the type of stainless steel suitable for use. From SS410 to SS316, they all have different uses.
