1. Martian bulk iron stainless steel: this kind of stainless steel body centered cubic structure (BCC) can attract the magnet and quench it from Austin temperature. This kind of stainless steel has the best corrosion resistance, but the material is hard and brittle. After tempering, the ductility can be increased, but the corrosion resistance will be reduced, especially when tempering at 450 ℃ to 650 ℃, the carbon atoms in the crystal lattice gap will be diffused and precipitated It is necessary to pay special attention to the loss of corrosion resistance due to the consumption of chromium element in the adjacent area caused by chromium carbide forming a network with chromium, resulting in the reduction of chromium content and failure to form a protective film. The following is the heat treatment temperature of various hemp iron stainless steel.
(1) The temperature of 403410416se was 650-750 ℃.
(2) The temperature of 414 is 650-730 ℃.
(3) The temperature of 431 is 6. (d) 440-a, 440-b, 440-c, and 420 is 680-750 ℃.
2. Ferritic stainless steel: this kind of bcc structure can attract magnets. It is usually used in automobile industry or chemical industry. Its strength will not be changed by heat treatment, but it can be increased by cold working.
3. Austin iron stainless steel: this kind of stainless steel face centered cubic structure (FCC) does not work on the magnet. As mentioned above, this kind of material is easy to process, so the residual stress of the material can be eliminated after processing and different heat treatment can be applied.
4. Precipitation hardening stainless steel: This stainless steel is quenched at high temperature and then heat treated at low temperature. The strength or hardness of this stainless steel can be improved by precipitation of aluminum or copper elements in the material along the slip surface or grain boundary of differential row to form compounds. The commonly used precipitation hardening stainless steel is 17-4PH, others are 17-7ph, ph15-7mo, am-350, am-355, etc.
5. Post weld heat treatment of all kinds of stainless steel: after welding, the chromium element contained in stainless steel will diffuse and precipitate in the high temperature area (heat affected zone) to synthesize chromium carbide, resulting in the reduction of local chromium content and failure to form a protective film. Corrosion such as perforation often occurs in these heat affected zones, which can remedy this situation The heat treatment of the object can make the chromium element in other areas diffuse to the chromium deficient area, so as to achieve the protective effect.