For casting engineers and mechanical structure design engineer, heat treatment is a very meaningful, and with a very high value to improve the method of material quality, through heat treatment can change or influence the organization and properties of cast iron, and can obtain higher strength, hardness, and improve the wear resistance and so on.
Because the purpose of so many different kinds of heat treatment, the basic can be mainly divided into two categories, the first category is the organization structure will not change or by heat treatment should not be changed, the second is the basic organizational structure change. The first heat treatment procedure, is mainly used to eliminate internal stress, and the internal stress is in the process of casting due to different cooling condition and conditions. Organization, strength and other mechanical properties, no obvious changes due to heat treatment. For the second heat treatment, al qaeda has had the obvious change, can be roughly divided into five categories: (1) the softening annealing: its purpose is to decompose the carbide, its hardness is reduced, and improve the processing performance, for the spherical graphite cast iron, its aim is to obtain iron group has a very high fertility. (2) the normalization processing: mainly used to improve or made entirely wave to iron casting for mechanical properties of uniform distribution. (3) hardening: mainly in order to obtain a higher hardness and abrasion strength, at the same time to the surface of the high wear-resisting properties. (4) surface hardening treatment: mainly for surface hardening layer, and received very high surface wear-resisting properties. (5) precipitation hardening treatment: mainly in order to obtain high strength and elongation is not so violent change.
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