Heat treatment. Quenching of steel, quenching hardening

Quenching consists in heating the steel to a temperature above the GSK line by 3050 degrees, followed by rapid cooling. As a result, the hardness and strength of the steel increase, and the ductility decreases. Quenching leads to formation of supersaturated solid solutions, and can be used for any metals and alloys in which the crystal structure tends to rearrange upon cooling. Carbon steels are quenched in water, and many alloy steels, in which diffusion processes proceed slowly, can be quenched in oil or even in air. The strong hardening of steels during quenching is due to the formation of martensite, a supersaturated solid solution of carbon in αFe. Carbon steels are vulnerable to sharp embrittlement during quenching. The ductility of quenched steels may be enhanced and residual stresses relieved by a heat treatment known as tempering. Used video rgl1925