Continuous casting billets without surface crackings and manufacture of non-treated high tension steel by using same

Application Number: 00107039
Application Date: 2000.03.10
Publication Number: 1270237
Publication Date: 2000.10.18
Priority Information: 1999/3/10 JP 62753/99
International: C21D8/00;C22C38/14
Applicant(s) Name: Kawasaki Steel Corp.
Inventor(s) Name: Oshimori Akio;Kawabata Fumimaru;Amano Kenichi
Patent Agency Code: 72001
Patent Agent: tai gong
Abstract N-V(nitrogen-vanadium) containing continuous casting slab with no surface cracks suitable for the manufacture of non-tempered high tensile steel materials has a tensile strength of 490 MPa or more and excellent toughness. A method of manufacturing non-tempered high tensile steel materials uses the casting slab as the raw material. Compatibility between the desired properties of the materials utilizing VN and inhibition of the surface cracks of test pieces, can be attained by controlling the steel composition and the relationship between each of components of the steel thereby controlling precipitation of VN and MnS. A continuous casting slab with no surface cracks contains C, Si, Mn, P, S, Al, V, N, Ti, B, Ca and REM each within a specified range, and satisfies an equation for the relationship between V and N and a relationship between Mn and S.