Kawasaki Steel Corporation

Kouichi Hirata

Masahiko Morita

Susumu Okada

Tsuguhiko Nakagawa

Susumu Sato

Susumu Satoh

A high tensile steel sheet excelling in workability and stretch flanging formability, which is of a composite texture composed of a ferrite phase and a 2nd phase selected from the group consisting of martensite, bainite, pearlite, retained austenite and cold-transformed ferrite, wherein the volume fraction of the 2nd phase is hoe less than about 1.3 times higher at an outer region of the steel sheet than the volume fraction of the 2nd phase in a central region of the sheet thickness.

Method of producing a high tensile steel sheet having excellent stretch

The present invention provides a steel sheet for press working that exhibits excellent stiffness and satisfactory press workability. The steel sheet for press working includes: a composition of C+N+B=0.007 to 1.0 wt % in a region from the surface of the steel sheet to a position of 5% of the thickness in a direction of the thickness in at least either of the surface layers; a pole intensity of [{321}+{211}]/{100}.gtoreq.1.2 in a vertical direction to the sheet surface realized at a 3% thickness position in the direction of the thickness from the surface; and a composition of C+N+B=0.010 wt % less than in the central portion 40% except for two 30% portions of the two surface layers in the direction of the thickness.

Steel sheet for press working that exhibits excellent stiffness and

A high tensile steel sheet excelling in workability and stretch flanging formability, which is of a composite texture composed of a ferrite phase and a 2nd phase selected from the group consisting of martensite, bainite, pearlite, retained austenite and cold-transformed ferrite, wherein the volume fraction of the 2nd phase is not less than about 1.3 times higher at an outer region of the steel sheet than the volume fraction of the 2nd phase in a central region of the sheet thickness.

Growing community of inventors

Chiba, Japan

Kouichi Hirata