MANUFACTURE OF HOT ROLLED WIRE ROD OF LOW CARBON KILLED STEEL HAVING LONG SERVICE LIFE OF DIE IN COLD FORGING

摘要

PURPOSE:To manufacture a hot rolled wire rod of a low-carbon killed steel, which gives a long service life to a cold forging die, by rolling a billet of a low-carbon killed steel characterized with a prescribed Al/N ratio, at limited heateing and rollling temperatures. CONSTITUTION:A low-carbon killed steel billet consisting of =0.25% C, =0.30% Si, 0.30-0.60% Mn, =0.05% P plus S, =0.008% N, =0.08% acid soluble Al, Al/N=1.0, and the balance comprising inevitable impurities plus Fe is prepared. This billet is rolled to a wire rod at rolling temperatures =Ar1 point (650-680 deg.C) and =Ar3 point (780-860 deg.C), after heating to 850-950 deg.C. By the present method, Al/N of the billet almost perfectly precipitates in a ferrite-austenite eutectic region on the way of the rolling process. The rod obtained by the present method displays an effect of improving the service life of a die for serving a severe cold working process, even if the annealing process is omitted.