Martensitic stainless steel generally needs to be quenched. For example, when used as tool steel, its hardness must be increased through the quenched state. However, martensitic steel is also widely used in structural steel. At this time, heat treatment must be quenched and tempered (quenching + tempering). For the tempering treatment of martensite, some details must be paid attention to.
1. Martensitic stainless steel has temper brittleness. Therefore, the cooling rate and tempering temperature during tempering must be selected appropriately.
2. The first type of temper brittleness depends on the tempering temperature, so it cannot be tempered within a certain temperature range. Secondly, the corrosion resistance is also very bad in a certain tempering temperature range. Because the temperature range of the first type of temper brittleness and corrosion resistance is basically the same, it is necessary to avoid tempering in this temperature range. fire.
3. The second type of temper brittleness means that the impact value decreases when the tempering temperature is slowly cooled. When this kind of steel is used as a structural steel, great attention is paid to the impact value. Therefore, the cooling rate of tempering must be changed with the required mechanical properties.