| 摘要 |
A method of hardening plain carbon or low alloy steel comprises austenizing the steel, cooling slowly to below the austenizing temperature but still high enough to prevent the formation of pro-martensite precipitations, water quenching to form martensite in the surface layers, interrupting the quench to allow the core to transform partially to martensite and then continuing the cooling at a rate slower than water-quenching to effect tempering of the surface layers to produce a lightly tempered martensitic structure throughout the section. The steel may be fully tempered at some later time. The preliminary slow cooling may be in air and the water quench may be interrupted at such time as will give an evening-up temperature of 200-225 DEG C. The duration of the water quench is directly proportional to the square of the diameter of round bars and to the square of the thickness measured across the flats in square, hexagonal, or octagonal sections. |
