STEEL FOR MACHINE STRUCTURAL USE HAVING EXCELLENT HOT WORKABILITY, COLD WORKABILITY AND HARDNESS AFTER COLD WORKING

摘要

PROBLEM TO BE SOLVED: To provide a steel for machine structural use which can secure hot workability, cold workability and hardness after cold working.;SOLUTION: The steel for machine structural use having excellent hot workability, cold workability and hardness after cold working has a composition containing, by mass, 0.0005 to 0.025% C, 0.005 to 0.03% Si, 0.4 to 1.0% Mn, ≤0.05% (not including 0%) P, 0.005 to 0.05% S, 0.01 to 0.05% Al, 0.007 to 0.03% Ti and 0.009 to 0.013% N, and the balance iron with inevitable impurities, wherein the content of N as a solid-solution state is 0.004 to 0.0075%, and also the Ti content and the N content satisfy the relation in the following inequality (1):0.60≤[Ti]/[N]≤3.00...(1), wherein [ ] denotes the content (mass%) of each element.;COPYRIGHT: (C)2011,JPO&INPIT