The difference between the heat treatment of steel castings and their corresponding carbon steels:

When heat treatment of cast steels with the same element content than the corresponding carbon steel or alloy steel, the corresponding quenching or complete annealing is performed. At this time, the holding temperature is slightly higher, generally 10 to 20 degrees higher, depending on the heat treatment furnace that performs the treatment.

Ordinary carbon steel refers to profiles, that is, steel ingots are made by blanking and (hot, cold) rolling. They have a dense structure, small and uniform grains, and high mechanical properties; while cast steel Steel is a steel ingot that is melted and cast again. It inevitably has defects in the casting process, such as changes in composition, coarse grains, prone to shrinkage, porosity and other casting defects. Therefore, the scrap rate is high and the mechanical properties are poor.

Cast steel is a casting that is used directly after being obtained by casting. Generally, the content of alloy elements is basically the same as that of the corresponding grade of material, but there will inevitably be a small number of defects.

The heat treatment process of cast steel:

The purpose of diffusion annealing (high temperature homogenization annealing) is to eliminate and reduce component segregation in the workpiece and improve the properties of certain soluble inclusions (such as sulfide (material) form, making the composition, internal structure, and mechanical properties of the workpiece uniform and stable

Normalizing and tempering: Refining the internal structure through recrystallization, improving strength and toughness, and making the workpiece similar to Obtain good comprehensive mechanical properties and improve cutting performance. ?

Annealing: Stabilizes the size of the workpiece and significantly improves the plasticity and toughness of the workpiece.

Quenching and tempering: Through conditioning, the comprehensive mechanical properties can be greatly improved.

Stress relief annealing: The purpose is to eliminate the internal stress in casting. The annealing temperature must be 10-30 degrees lower than the tempering temperature. Carbon steel can undergo certain heat treatments as needed, and diffusion annealing is not required.