PURPOSE:To obtain a tenacious steel for cold forging with improved cold forgeability, by reducing the contents of Si, Mn, P, Al, N and O in a machine structural carbon steel to prescribed amounts or less and by adding small amounts of Ti, B and Ca. CONSTITUTION:The contents of Si, Mn, P, Al, N and O in a machine structural carbon steel contg. 0.4-0.75% C are reduced to =0.1% Si, =0.4% Mn, =0.01% P, =0.01% Al, =0.005% N and =0.005% O, and =0.05% Ti, =0.003% B and =0.01% Ca are added to the steel. =0.8% Cr may be added furthermore. The contents of said components in the carbon steel are reduced, the insufficient hardenability is compensated by adding Ti and B, and Ca is actively added to cause deoxidation. As a result, a steel material with remarkably improved deformation resistance and deformability is obtd.
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