Stahlblech, Element und Herstellungsverfahren dafür

Details

Veröffentlichungs-Nr.

EP4752251

Anmeldetag

3. Oktober 2024

Veröffentlichung

10. April 2025

Rechtsraum

EP

Abstract

To provide a steel sheet having a TS of 1180 MPa or more and less than 1470 MPa, high YS, high ductility, high press formability in the inner portion of the steel sheet and at the end portion of the steel sheet, and high crack propagation resistance. The steel sheet has a base steel sheet having a predetermined chemical composition and has a surface soft layer having a Vickers hardness of 84% or less relative to that at the quarter thickness from the surface of the base steel sheet and satisfying the following formula (1), wherein the surface soft layer has a microstructure in a specific range, the base steel sheet has a microstructure in a specific range at the quarter thickness, the length of a crack that propagates from a bending ridge line end portion in a ridge line direction is 200 µm or less in a 90-degree V-bending test with a bending radius of 0.5 mm, El is 6.0% or more in a notch tensile test after a heat treatment at 170°C for 20 minutes, and El is 5.0% or more in a notch tensile test after a nominal tensile strain of 2% is introduced and after a heat treatment at 170°C for 20 minutes is performed. 20 ≤ X ≤ 120 − 3800 × Sb − 1900 × Sn <img class="EMIRef" id="05b76f3d-cb48-4209-86f8-c31468675743-ia01" />

Anmelder

Firma

JFE Steel Corporation

Land

🇯🇵 Japan