| 摘要 |
PURPOSE:To produce efficiently mechanical structural parts having high quality with a simplified process and lessened manpower by heating and hot rolling a steel contg. a specific ratio of C, Si, Mn, Nb, solAl, B and N under specific conditions. CONSTITUTION:A steel contg., by weight %, 0.04-0.10% C, <=0.50% Si, 0.80- 2.50% Mn, 0.01-0.10% Nb, 0.01-0.05% solAl, 0.0005-0.0035% B, and <=0.0045% N and consisting of the balance Fe and unavoidable impurities is heated to 1,000-1,200 deg.C. The steel is then hot rolled at >=60% cumulative draft at 850- 1,000 deg.C and a finishing temp. of 800-950 deg.C. The steel for machine structural parts having combined high strength and good toughness is thus obtd. without requiring a softening treatment prior to cold working and a hardening treatment in the stage of tempering. |
