Characteristics of Casting
Casting is a relatively economical method of blank forming, which can better demonstrate its economy for parts with complex shapes. Such as the cylinder and cylinder heads of automobile engines, ship propellers, and exquisite works of art. Some parts that are difficult to cut, such as nickel based alloy parts of gas turbines, cannot be formed without casting methods.
For casting engineers and mechanical structure design engineers, heat treatment is a very meaningful and valuable method for improving material quality. Through heat treatment, the structure and properties of cast iron can be changed or affected, while achieving higher strength and hardness, improving its wear resistance, and so on.
Due to different purposes, there are many types of heat treatment, which can be divided into two main categories: one is that the tissue structure does not change or should not change through heat treatment, and the other is that the basic tissue structure changes. A heat treatment procedure mainly used to eliminate internal stresses caused by different cooling conditions and conditions during the casting process. The structure, strength, and other mechanical properties do not change significantly due to heat treatment.
For the second type of heat treatment, significant changes have taken place in Al Qaeda, which can be broadly divided into five categories:
(1) Casting softening annealing: Its main purpose is to decompose carbides, reduce their hardness, and improve processing performance. For ductile iron, its purpose is to obtain more ferrite structure.
(2) Normalizing treatment: The main purpose is to obtain pearlite and sorbite structures to improve the mechanical properties of the casting.
(3) Quenching: Mainly for obtaining higher hardness or wear strength, while achieving very high surface wear resistance characteristics.
(4) Surface Hardening Treatment: Mainly used to obtain a surface hardened layer while obtaining very high surface wear resistance characteristics.
(5) Precipitation hardening treatment: Mainly used to obtain high strength without drastic changes in elongation.
