公开(公告)号：US20220098712A1

公开(公告)日：2022-03-31

申请号：US17422870

申请日：2020-02-13

Applicant: NIPPON STEEL CORPORATION

Inventor： Hiroki KAMITANI ,  Yohei OTOME ,  Atsushi SOMA ,  Taro OE ,  Nobuaki KOMATSUBARA ,  Shinji YOSHIDA ,  Yuji ARAI

IPC: C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/30 ,  C22C38/20 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00

Abstract: A steel material according to the present disclosure has a chemical composition consisting of, in mass %: C: 0.20 to 0.45%, Si: 0.05 to 1.00%, Mn: 0.01 to 1.00%, P: 0.030% or less, S: 0.0050% or less, Al: 0.005 to 0.100%, Cr: 0.60 to 1.50%, Mo: more than 1.00 to 2.00%, Ti: 0.002 to 0.020%, V: 0.05 to 0.30%, Nb: 0.005 to 0.100%, B: 0.0005 to 0.0040%, N: 0.0100% or less, O: less than 0.0020%, and the balance being Fe and impurities, and satisfying Formula (1) described in the specification. A grain diameter of a prior-austenite grain is 11.0 μm or less, and an average area of precipitate which is precipitated in a prior-austenite grain boundary is 10.0×10−3 μm2 or less. A yield strength is 758 to 862 MPa.

公开(公告)号：US20210262051A1

公开(公告)日：2021-08-26

申请号：US17265614

申请日：2019-10-16

Applicant: NIPPON STEEL CORPORATION

Inventor： Yuji ARAI ,  Shinji YOSHIDA ,  Hiroki KAMITANI ,  Yohei OTOME

IPC: C21D8/10 ,  C21D9/08 ,  C21D6/00 ,  C22C38/54 ,  C22C38/44 ,  C22C38/46 ,  C22C38/00

Abstract: The steel material according to the present disclosure has a chemical composition consisting of, in mass %, C: 0.15 to 0.45%, Si: 0.05 to 1.00%, Mn: 0.01 to 1.00%, P: 0.030% or less, S: 0.0050% or less, Al: 0.005 to 0.100%, Cr 0.60 to 1.80%, Mo: 0.80 to 2.30%, Ti: 0.002 to 0.020%, V: 0.05 to 0.30%, Nb: 0.002 to 0.100%, B: 0.0005 to 0.0040%, Cu: 0.01 to 0.50%, Ni: 0.01 to 0.50%, N: 0.0020 to 0.0100% and O: 0.0020% or less, with the balance being Fe and impurities. The number density of BN in the steel material is 10 to 100 particles/100 μm2. The yield strength of the steel material is 758 MPa or more.