Tensile strength, fatigue strength and the non heat treated steel null for hot forging which is superior in

摘要

PURPOSE: To obtain a non-heat treated steel for hot forging excellent in tensile strength, fatigue strength and machinability by specifying the chemical components in a steel and controlling its metallic structure. ;CONSTITUTION: This steel contains, by weight, 0.10 to 0.35% C, 0.15 to 2.00% Si, 0.40 to 2.0% Mn, 0.03 to 0.10% S, 0.0005 to 0.050% Al, 0.003 to 0.050% Ti, 0.0020 to 0.0070% N, 0.30 to 0.70% V, and the balance Fe with inevitable impurities, and in its metallic structure after cooling at a room temp. following hot forging, the structural rate (f) of the bainitic structure is regulated to 1.4C+0.4≥f≥1.4C based on the C-contg. %. Thus, the ferrite-bainite type non- heat treated steel having high tensile strength, high fatigue strength and excellent machinability and used in hot-forged state as it is can be obtd..;COPYRIGHT: (C)1995,JPO