Patent ID: 11085101

Abstract:
Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing as high as TS: 1780 MPa or more and excellent delayed fracture resistance after projection welding by properly adjusting its chemical composition and its microstructure such that at least 5 Ti-based precipitates having a grain size of 0.10 μm or less are present on average per 100 μm2 of a cross section parallel to a thickness direction of the member within a range of 100 μm in a thickness direction from a surface of the member, a volume fraction of martensite is 95% to 100% within a depth range of 20 μm to 100 μm in the thickness direction from the surface of the member, and at least 10 cementite grains having a grain size of less than 0.20 μm are present on average in a prior austenite grain.