Household stainless steel can be divided into 430, 304 (18-8), 18-10 three grades.
430 stainless steel: iron + 12% more chromium, can prevent oxidation caused by natural factors, called stainless steel, in the jis code for 430, so also known as 430 stainless steel. But 430 stainless steel can not resist the oxidation caused by chemicals in the air, 430 stainless steel is not often used for a period of time, there will still be oxidation (rust) due to unnatural factors;
18-8 stainless steel: Iron +18% chromium +8% nickel, can resist chemical oxidation, this stainless steel in the jis code for 304, so it is also known as 304 stainless steel;
18-10 stainless steel: iron +12% chromium, can prevent oxidation caused by natural factors, called stainless steel, in the jis code for 430, therefore also known as 304 stainless steel. p>
18-10 stainless steel: but the chemical composition of the air more and more, some of the more polluted places even 304 will have rust; so there are high-level supplies will be made with 10% nickel to make it more durable and more corrosion-resistant, this stainless steel is called 18-10 stainless steel. In some cutlery instructions have something like "using 18-10 the most advanced medical stainless steel material". (It can also be said to be food-grade stainless steel)
The three kinds of stainless steel, the simplest way to distinguish between them is: use a magnet to suck the bottom of the suction, suction is 430, suction is not 304 and 18-10. 304 pots and pans rim, or spoons front and back, sometimes suction because of the polished magnetism. So the most accurate way is to suck the bottom.
Grouping of stainless steel grades:
200 Series - Chromium-Nickel-Manganese Austenitic Stainless Steel
300 Series - Chromium-Nickel Austenitic Stainless Steel
Type 301 - Ductile, used for molded products. Can also be hardened rapidly by machining. Weldability is good. Wear resistance and fatigue strength superior to 304 stainless steel.
Type 302-Corrosion resistance is the same as 304, with better strength due to relatively higher carbon content.
Type 303- By adding a small amount of sulfur and phosphorus to make it easier to cut and process than 304.
Type 304-Universal type; i.e. 18/8 stainless steel. GB grade is 0Cr18Ni9.
Type 309- Better temperature resistance than 304.
Type 316-after 304, the second most widely used steel, mainly used in the food industry and surgical equipment, the addition of molybdenum to obtain a corrosion-resistant special structure. It is also used as a "marine steel" because of its better resistance to chloride corrosion than 304, and SS316 is commonly used in nuclear fuel recovery units. 18/10 grade stainless steel is also commonly used in this application.
Type 321 - Similar properties to 304 except that the addition of titanium reduces the risk of corrosion in the weld seams of the material.
400 Series - Ferritic and Martensitic Stainless Steels
Type 408 - Good heat resistance, weakly corrosion resistant, 11% Cr, 8% Cr. 11% Cr, 8% Ni.
Type 409-The cheapest type (Anglo-American), usually used as automobile exhaust pipes, is a ferritic stainless steel (chromium steel).
Type 410-Martensitic (high-strength chromium steel), good wear resistance, poor corrosion resistance.
Type 416-added sulfur improves the machinability of the material.
Type 420-"Sharpening grade" martensitic steel, similar to Brinell high-chromium steel, the earliest stainless steel. Also used for surgical knives, which can be made very bright.
Type 430-Ferrite stainless steel, decorative, e.g. for automotive jewelry. Good formability, but temperature resistance and corrosion resistance are inferior.
Type 440-High-strength sharpening steel, slightly higher in carbon, with high yield strength and hardness up to 58 HRC after appropriate heat treatment, among the hardest stainless steels. The most common application example is "razor blades". There are three common types: 440A, 440B, 440C, and 440F (easy to machine).
500 Series - Heat-resistant chrome alloy steel.
600 Series - Martensitic precipitation hardening stainless steel.
Type 630-the most commonly used precipitation hardening stainless steel type, usually also called 17-4; 17%Cr, 4%Ni
The above data is provided for reference, please take the advice.