US2026085391A1PendingUtilityA1

Hot rolled steel sheet

Assignee: NIPPON STEEL CORPPriority: Nov 2, 2022Filed: Jun 30, 2023Published: Mar 26, 2026
Est. expiryNov 2, 2042(~16.3 yrs left)· nominal 20-yr term from priority
Inventors:SHIMADA TAKASHI
C22C 38/14C22C 38/12C22C 38/06C22C 38/02C22C 38/002C22C 38/001C21D 2211/008C21D 2211/005C21D 2211/002C21D 9/46C21D 8/0226C21D 2211/004C22C 38/008C22C 38/005C22C 38/42C22C 38/44C22C 38/46C22C 38/48C22C 38/50C22C 38/52C22C 38/54C22C 38/58C22C 38/60C22C 38/004C22C 38/16C22C 38/22C22C 38/26C22C 38/28C22C 38/32C22C 38/38C22C 38/08C22C 38/04C21D 8/0263C21D 8/02
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Claims

Abstract

Provided is a hot rolled steel sheet having a predetermined chemical composition, and a microstructure comprising, by area ratio, ferrite: 60 to 80%, bainite: 15 to 30%, and martensite: 3 to 10%, wherein TiC precipitates having a diameter of 1.0 to 5.0 nm are present in the ferrite in a number density of 1.0×1016 to 100.0×1016/cm3, and the hot rolled steel sheet has a tensile strength of 780 MPa or more tensile strength.

Claims

exact text as granted — not AI-modified
1 . A hot rolled steel sheet having a chemical composition comprising, by mass %,
 C: 0.010 to 0.100%,   Si: 0.01 to 0.10%,   Mn: 0.50 to 3.00%,   Ti: 0.050 to 0.200%,   Nb: 0.010 to 0.020%,   Al: 0.100 to 1.000%,   P: 0.1000% or less,   S: 0.0100% or less,   N: 0.0100% or less,   O: 0.0100% or less,   Ni: 0 to 2.000%,   Mo: 0 to 1.000%,   Cr: 0 to 2.000%,   B: 0 to 0.0100%,   Co: 0 to 2.000%,   V: 0 to 1.000%,   Cu: 0 to 2.000%,   W: 0 to 1.0000%,   Ta: 0 to 1.0000%,   Sn: 0 to 1.0000%,   Sb: 0 to 1.0000%,   As: 0 to 0.0100%,   Mg: 0 to 0.0100%,   Ca: 0 to 0.0100%,   Zr: 0 to 0.0100%,   Hf: 0 to 0.0100%,   Bi: 0 to 0.0100%,   REM: 0 to 0.0100%, and   balance: Fe and impurities, and   a microstructure comprising, by area ratio,   ferrite: 60 to 80%,   bainite: 15 to 30%, and   martensite: 3 to 10%, wherein   TiC precipitates having a diameter of 1.0 to 5.0 nm are present in the ferrite in a number density of 1.0×10 16  to 100.0×10 16 /cm 3 , and   the hot rolled steel sheet has a tensile strength of 780 MPa or more.   
     
     
         2 . The hot rolled steel sheet according to  claim 1 , wherein the chemical composition contains, by mass %, at least one of:
 Ni: 0.001 to 2.000%,   Mo: 0.001 to 1.000%,   Cr: 0.001 to 2.000%,   B: 0.0001 to 0.0100%,   Co: 0.001 to 2.000%,   V: 0.001 to 1.000%,   Cu: 0.001 to 2.000%,   W: 0.0001 to 1.0000%,   Ta: 0.0001 to 1.0000%,   Sn: 0.0001 to 1.0000%,   Sb: 0.0001 to 1.0000%,   As: 0.0001 to 0.0100%,   Mg: 0.0001 to 0.0100%,   Ca: 0.0001 to 0.0100%,   Zr: 0.0001 to 0.0100%,   Hf: 0.0001 to 0.0100%,   Bi 0.0001 to 0.0100%, and   REM: 0.0001 to 0.0100%.

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