When steel contains other ferrite forming elements, in order to obtain pure austenite structure, the nickel content must be increased. Heat treatment of heat-resistant steel castings should be based on reasonable accumulation of layout characteristics to prevent deformation as much as possible. When the as-cast segregation of castings is severe, uniform treatment is required to eliminate the influence on the end function of castings.1% and the carbon content is 18%, the nickel content is only 8% in order to obtain the pure austenite structure of the steel.
During thermal treatment, the heating temperature should be slightly higher than that of forged steel parts of the same composition, and the austenitizing heat preservation time should also be properly extended. For steel castings with disordered shapes and large wall thickness differences, it is necessary to consider the cross-sectional effect and casting stress during thermal treatment. . Molybdenum is a refractory metal with a high melting point. The high temperature corrosion resistance of heat resistant steel is related to its chromium content.The main elements in heat resistant steel castings are resistant to high temperature oxidation and high temperature corrosion, and can improve the thermal strength of heat resistant steel.
Heatresistance steel castings are widely Heat treatment material Castings used Heat resistant steel castings is a very excellent casting process and is widely used, suitable for casting various types of alloys.In order to obtain pure austenite structure of steel at room temperature, the nickel content is not less than 25%, but when the steel contains other alloy elements, the nickel content can be appropriately reduced to obtain pure austenite structure. For example, when the carbon content in the steel is 0. It has a good effect on improving the heat strength of heat resistant steel. If the nickel content is not increased or decreased, bidirectional structure or unstable austenite structure will appear, and phase transformation may occur during cold working.
Therefore, the chromium content of commonly used heat-resistant steel should not be lower than that of nickel, which is one of the important alloy elements in heat-resistant steel
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