JPS54127820A - High toughness steel material for hot working - Google Patents

Abstract

PURPOSE: To prevent toughness deteriotation after hot working process, a carbon steel or a low alloy steel is limited in the contents of oxygen, sulfur, and inclusives of more than 5μ to below a specified value, the steel further being added with Mg, Ca, or rare earth element, etc.

CONSTITUTION: In either a normal carbon steel containing C: 0.03 to 0.80%, Si: 0.05 to 1.0%, Mn: 0.30 to 2.0% or a low alloy steel additionally containing one or more of Cu<0.60%, Ni<6.0%, Cr<3.0%, Mo<2.0%, V<0.10%, Nb<0.10%, Al<0.10%, Ti<0.10%, Zr<0.10%, B<0.006%, the contents of both O and S are specified to less than 0.0020%. The inclusive content of more than 5μ is limited to less than 10% of the total inclusives. Or further, one or more of Mg, Ca, and rare earth element are incorporated in an amount of 0.05% or less. The restriction and addition of such components and the inclusive limitation synergistically operate to effect that an excellent toughness is maintained after hot working such as press forming, spinning processing and casting.

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