2、 Classification of metal materials

(1) The standard martensitic stainless steel plate is usually made of four models: 302, 303, 304 and 305, namely, the "18-8" martensitic stainless steel plate. Both corrosion resistance and physical properties are similar. The base point adopted is the processing technology of half empty central bolt, and the way lies in the specification and appearance of the half empty central bolt, and also in the total number. Type 302 is used to produce and manufacture screws and self tapping anchor bolts. In order to improve the characteristics and have a small amount of sulfur, 303 is used to regulate nuts. 304 type is suitable for the hot heading processing process, such as long specification anchor bolts and large diameter anchor bolts. Model 305 is suitable for cold heading process to produce and manufacture half empty central bolts, such as cold forming nuts and hexagon bolts. The magnesium content and nickel content of 309 and 310 type are higher than those of 18-8 stainless steel plate, which are suitable for half empty central bolts manufactured at high temperature. 316 and 317, both of them have aluminum alloy manganese, so their high temperature compressive strength and corrosion resistance are higher than 18-8 stainless steel plate. The stress corrosion resistance of the raw materials was improved by 321 and 347, 321 with stable aluminum alloy titanium, 347 with Nb and double drum rivets.

(2) The austenitic stainless steel plate 410 and 416 can be used to strengthen the heat treatment process, and can be used for the high temperature and corrosion resistance half empty center bolts for general purpose. 416 type is easy to cut stainless steel plate with a higher sulfur content. The physical properties of 420 type are improved, and the heat treatment process can be strengthened to specify the high toughness half empty center bolt.

(3) The corrosion resistance and temperature resistance of 430 type general manganese steel of ferritic stainless steel plate are better than 410 type, but it can not be strengthened by heat treatment process. It is suitable for semi empty central bolts of stainless steel plate with slightly higher corrosion resistance and higher temperature resistance and general compression strength.

(4) The 17-4PH and ph15-7mo of the hard bottom stainless steel plate can obtain higher compressive strength than the general 18-8 stainless steel plate, so they are used for high toughness, automobile lantern rivets and corrosion resistant stainless steel plate half empty center bolts. A-286 is a non-standard stainless steel plate, which has higher corrosion resistance than the common 18-8 stainless steel plate, and it still has excellent physical properties when the temperature is increased. It is used as high toughness, high temperature resistant and corrosion resistant half empty center bolt.