Stainless solution treatment
Solid solution treatment is to dissolve matrix carbide, which is equal to uniform supersaturated solid solution. Precipitation of fine particles promotes the uniform distribution of carbide and gamma phase, and reinforcement is similar, eliminating cold and hot stress recrystallization of processed alloys. Secondly, the solution treatment is to obtain the appropriate grain size to ensure the creep resistance of the alloy at high temperature. The temperature range of solid solution treatment is between 980 ~1250 ~C. The precipitation and dissolution of main phases and the requirements of selection rules must ensure that the conditions of main precipitation strengthening phases and grain size are in accordance with their respective alloys. For long-term use of superalloys, high solution temperature should be chosen to obtain larger grain size, which requires durability and good creep properties at high temperature. For use at high temperature and require better temperature hardness, yield strength, tensile strength, fatigue strength and impact toughness of alloys, lower solution temperature can be used to ensure smaller grain size. After high temperature solid solution treatment, the precipitation of each phase gradually dissolves and the grain grows. Low temperature solid solution heat treatment not only strengthens the phase dissolution, but also may have some precipitation. For alloys with low supersaturation, the faster the cooling rate is usually chosen; the supersaturation of alloys is usually in the cooling air.
SOLUTION HEAT TREATMENT OF STAINLESS STEEL
The solubility of carbon in austenitic stainless steel with temperature has a great influence. In austenitic stainless steel, there is a high precipitation of chromium carbide in the temperature range of 400 850 C. When the chromium content decreases below the boundary corrosion, the intergranular corrosion will occur at the grain boundary of chromium depletion, and the powder will become serious. Therefore, the intergranular corrosion tendency of austenitic stainless steel should be treated by solution heat treatment or stabilization treatment.
SOLUTION HEAT TREATMENT: Austenitic stainless steel is heated to about 1100 C, so that the carbide phase is completely or basically dissolved, and carbon is dissolved in austenite, then rapidly cooled to room temperature, so that carbon reaches saturation. This heat treatment method is used for solid solution heat treatment.
The rapid cooling of solution heat treatment quenching looks like ordinary steel, but this hardening ordinary steel "hardening" is different, the former softening, hardening. The heating temperature required to obtain different hardness is different, but not 1100 C.