Quenching hot rolled steel wire rod - by rapid cooling to above AC 3 temp. then slower cooling

摘要

In the heat treatment of wire rod and light sections of steel contg. =0.4% C by quenching from the rolling heat in the region of max. pearlite transformation rate to obtain good cold workability, quenching is carried out by multistage water quenching in two sections. In the first section, the steel is intensively quenched to an equilibrium temp. just above the Ac3 point, the martensite formed in the outer layer of the steel being transformed back to austenite before the second section. In the second section, the steel is subjected to multistage cooling at a lower controlled cooling intensity. Method allows increased cooling rates to be used so that wire rod of =20mm dia can be patented.