Household stainless steel is divided into three grades: 430, 304 (18-8) and 18- 10.
430 stainless steel: Iron+12% or more chromium can prevent oxidation caused by natural factors, so it is called stainless steel. It is code-named 430 in jis, so it is also called 430 stainless steel. However, 430 stainless steel cannot resist oxidation caused by chemicals in the air. 430 stainless steel will still be oxidized (rusted) due to unnatural factors after not being used frequently for a period of time.
18-8 stainless steel: iron+18% chromium +8% nickel, resistant to chemical oxidation. This kind of stainless steel is 304 in jis code, so it is also called 304 stainless steel;
18- 10 stainless steel: but there are more and more chemical components in the air, and even 304 will rust in some seriously polluted places; Therefore, some advanced articles will be made of 10% nickel to make them more durable and corrosion-resistant. This kind of stainless steel is called 18- 10 stainless steel. In the description of some tableware, there is a statement similar to "using 18- 10 the most advanced medical stainless steel material". (It can also be said to be food-grade stainless steel)
The simplest way to distinguish these three kinds of stainless steel is to use a magnet to hold the bottom, which can hold 430, but not 304 and 18- 10. However, the edge of the 304 pot, or the front and rear ends of the spoon, is sometimes attracted by the magnetism generated by grinding. So the most accurate way is to suck the bottom.
Stainless steel brand grouping:
200 Series-Cr-Ni-Mn Austenitic Stainless Steel
300 series-Cr-Ni austenitic stainless steel
Model 30 1- has good ductility and is used for molding products. It can also be rapidly hardened by machining. Good weldability. Wear resistance and fatigue strength are better than 304 stainless steel.
Type 302-corrosion resistance is the same as that of 304, and its strength is better because of its relatively high carbon content.
Type 303-with a small amount of sulfur and phosphorus, it is easier to cut than type 304.
Model 304- General Model; Namely 18/8 stainless steel. GB brand is 0Cr 18Ni9.
Model 309- has better temperature resistance than 304.
Model 316-The second most widely used steel is mainly used in food industry and surgical instruments. Adding molybdenum makes it obtain a special corrosion-resistant structure. Because it has better chloride corrosion resistance than 304, it is also used as "marine steel". SS3 16 is usually used in nuclear fuel recovery devices. 18/ 10 stainless steel usually meets this application level.
Model 321-The performance is similar to that of 304, but the risk of welding corrosion is reduced due to the addition of titanium.
400 series-ferritic and martensitic stainless steels
Model 408- Good heat resistance, weak corrosion resistance, 1 1% chromium, 8% nickel.
Model 409-the cheapest model (Britain and America), usually used as an automobile exhaust pipe, belongs to ferritic stainless steel (chrome steel).
Model 4 10- martensite (high strength chromium steel) has good wear resistance and poor corrosion resistance.
Model 416-Adding sulfur can improve the processability of the material.
Type 420-"blade grade" martensitic steel, similar to Brinell high chromium steel, the earliest stainless steel. It can also be used for scalpels, which can be made very bright.
Model 430- ferritic stainless steel, used for decoration, such as automobile parts. Good formability, but poor temperature resistance and corrosion resistance.
Type 440-high-strength cutting tool steel, with a slightly higher carbon content, can obtain a higher yield strength after proper heat treatment, and its hardness can reach 58HRC, which is one of the hardest stainless steels. The most common application example is "shaving blade". There are three commonly used models: 440A, 440B, 440C and 440F (easy to process).
500 series-heat resistant chromium alloy steel.
600 series-martensitic precipitation hardening stainless steel.
Model 630- the most commonly used precipitation hardening stainless steel model, usually also called17-4; 17% Cr, 4% Ni
The above data are for reference, please adopt them.