Stahlblech, Widerstandspunktschweissverfahren, Widerstandspunktschweisselement und Verfahren zur Herstellung eines Stahlblechs

Details

Veröffentlichungs-Nr.

EP4756058

Anmeldetag

1. August 2024

Veröffentlichung

5. Juni 2025

Rechtsraum

EP

Abstract

A steel sheet is provided that has a tensile strength of 1600 MPa or more, high L-shape tension strength after resistance welding, and also has excellent delayed fracture resistance after resistance welding. The steel sheet has a defined chemical composition, wherein a microstructure at a 1/4 sheet thickness position contains, in volume fraction, ferrite: 0 % to 5 %, retained austenite: 0 % to 5 %, bainite: 0 % to 7 %, and martensite: 93 % or more, wherein an average grain size of ferrite is 3 µm or less, an average grain size of retained austenite is 3 µm or less, an average grain size of bainite is 5 µm or less, and an average grain size of martensite is 7 µm or less, wherein a microstructure in a region 7 µm to 12 µm from a surface in the sheet thickness direction contains a volume fraction of ferrite of 30 % or more, and an average grain size of ferrite is 10 µm or less, and wherein, in a region 50 µm to 100 µm from the surface in the sheet thickness direction, an average number density of carbides having a particle size of 0.10 µm or more is 5 per 100 µm² or more.

Anmelder

Firma

JFE Steel Corporation

Land

🇯🇵 Japan