Cast steel is used to cast steel for castings and is a type of cast alloy. At present, cast steel is mainly used to manufacture parts that are complex in shape, difficult to forge or cut, and require high strength and plasticity.
Cast steel can be divided into chemical composition: carbon cast steel and alloy cast steel. Carbon cast steel is divided into carbon content according to carbon content: C≤0.20% for low carbon cast steel; C0.2～0.5% for medium carbon steel; C≥0.5% for high carbon steel.
Cast steel is divided into alloy elements according to its content: low alloy steel (the total amount of alloy elements is below 8%) and high alloy steel (the total amount of alloy elements is above 8%).
Cast steel can be divided into: structural cast steel, wear-resistant cast steel, stainless cast steel, heat-resistant cast steel and tool cast steel.
Cast steel is divided into: pearlite-type cast steel, ferritic cast steel, martensitic cast steel and austenitic cast steel.
Cast steel is a type of casting. Therefore, the forged workpiece can improve the internal structure of the structure, the mechanical properties are good, the grains are uniform, and the important workpieces must be forged. It is believed that many casters need to pay attention to the process points of heat treatment of steel castings.
The main technological elements of heat treatment of steel castings:
1. The heat treatment of the steel casting consists of three stages of heating, heat preservation and cooling. The determination of the process parameters is based on ensuring product quality and cost savings.
2. The heat treatment method of steel castings is different according to the heating and cooling conditions. The main heat treatment methods of steel castings are: annealing normalizing, homogenizing treatment, quenching, tempering, solution treatment, precipitation hardening, stress relief treatment and hydrogen removal. deal with.
3. Annealing is a heat treatment process in which the steel castings are heated to a certain temperature or higher for a certain period of time and cooled. The purpose of annealing is to eliminate columnar crystals, coarse equiaxed grains, Wei's structure and dendritic segregation in the cast structure to improve the mechanical properties of the cast steel.
4. Structure after carbon steel annealing: The hypoeutectic cast steel is ferrite and pearlite, the eutectoid cast steel is pearlite, and the hypereutectoid cast steel is pearlite and carbide. Suitable for all grades of steel castings.