公开(公告)号：US20230140650A1

公开(公告)日：2023-05-04

申请号：US17906408

申请日：2021-04-05

Applicant: NIPPON STEEL CORPORATION

Inventor： Taizo MAKINO ,  Masahiro YAMAZAKI

IPC: F16L9/02 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00

Abstract: A steel pipe for pressure piping can be subjected to autofrettage. When an outer diameter of the pipe is D, an inner diameter is d, and a yield stress is σy, and when a measured value of an outer surface residual stress is σo1, a measured value of an outer surface residual stress after halving is σo2, and a measured value of an inner surface residual stress after the halving is σi2, D/d is 1.2 or more, an estimated value σi1 of inner surface residual stress is [σi1=(−σi2)/(A×(t/T)2−1)], where [t/T=((σo2−σo1)/(A×(σo2−σo1)−C×σi2))1/2], [A=3.9829×exp(0.1071×(D/d)2)], and [C=−3.3966×Exp(0.0452×(D/d)2)] satisfies [1.1×F×σy≤αi1≤0.8×F×σy], and (F=(0.3×(3−D/d)2−1) when 1.2≤D/d≤3.0, and F=−1 when D/d>3.0).

公开(公告)号：US20240093324A1

公开(公告)日：2024-03-21

申请号：US18256577

申请日：2022-01-07

Applicant: NIPPON STEEL CORPORATION

Inventor： Taizo MAKINO ,  Masahiro YAMAZAKI

IPC: C21D9/14 ,  C21D7/12 ,  C21D8/10 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/20 ,  C22C38/22 ,  C22C38/50 ,  F16L9/02

CPC classification number: C21D9/14 ,  C21D7/12 ,  C21D8/105 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/20 ,  C22C38/22 ,  C22C38/50 ,  F16L9/02

Abstract: A steel pipe for pressure piping subjected to autofrettage has an average hardness at its outer layer region of 1.20 times or more of an average hardness at its inner layer region. When an outer diameter is D, and an inner diameter is d, a measured value of a residual stress at an outer surface is denoted by σo1, a measured value of a residual stress at an outer surface after halving is denoted by σo2, and a measured value of a residual stress at an inner surface after the halving is denoted by σi2, an estimated value σi1 of a residual stress at the inner surface of the steel pipe is determined by [σi1=(−σi2)/(A×(t/T)2−1)], [t/T=((σo2−σo1)/(A×(σo2−σo1)−C×σi2))1/2], [A=3.9829× exp(0.1071×(D/d)2)], and [C=−3.3966×exp(0.0452×(D/d)2)] is −150 MPa or less.

公开(公告)号：US20220112572A1

公开(公告)日：2022-04-14

申请号：US17427864

申请日：2020-02-13

Applicant: NIPPON STEEL CORPORATION ,  USUI CO., LTD.

Inventor： Taizo MAKINO ,  Masahiro YAMAZAKI ,  Yuji ARAI ,  Osamu ENDO ,  Naoki SERIZAWA ,  Tatsuya MASUDA

IPC: C21D9/08 ,  F16L9/02 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/10 ,  C21D6/00

Abstract: A steel pipe for a fuel injection pipe has a chemical composition consisting of, by mass %: C: 0.17 to 0.27%, Si: 0.05 to 0.40%, Mn: 0.30 to 2.00%, P: 0.020% or less, S: 0.0100% or less, O: 0.0040% or less, Ca: 0.0010% or less, Al: 0.005 to 0.060%, N: 0.0020 to 0.0080%, Ti: 0.005 to 0.015%, Nb: 0.015 to 0.045%, Cr: 0 to 1.00%, Mo: 0 to 1.00%, Cu: 0 to 0.50%, Ni: 0 to 0.50%, V: 0 to 0.15%, and the balance: Fe and impurities. The metal micro-structure consists substantially of tempered martensite, or tempered martensite and tempered bainite. A prior-austenite grain size number is 9.0 or more. The hardness is within the range of 350 to 460 HV1. When a maximum value of a square root of an area of inclusions observed in a cross section perpendicular to a longitudinal direction of the steel pipe is taken as an (n=1 to 20), a maximum value amax of an is 30.0 μm or less, and an average value aav of an is 40% or more of amax.

公开(公告)号：US20230271635A1

公开(公告)日：2023-08-31

申请号：US18007428

申请日：2021-09-28

Applicant: NIPPON STEEL CORPORATION

Inventor： Taizo MAKINO ,  Chihiro KOZUKA ,  Yuichiro YAMAMOTO ,  Toshiyuki HATA ,  Akihito YAMANE

IPC: B61F15/20 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/22

CPC classification number: B61F15/20 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/22

Abstract: The railway axle according to this disclosure has a pair of fitting portions and which each include a fitting portion hardened layer and a base metal portion, and a center parallel portion which includes a center parallel portion hardened layer and the base metal portion. The base metal portion has the chemical composition described in the description. In a region having the Vickers hardness of 480 HV or more in the center parallel portion hardened layer, a dislocation density p obtained based on a CoKα characteristic X-ray diffraction result is 2.5×1016 m−2 or less, a half-value width B of the (211) diffraction plane is 1.34 degrees or less, and the dislocation density p and the half-value width B of the (211) plane obtained by X-ray diffraction satisfy Formula (1).


(−4.8×1016×B+8.5×1016)/ρ≥1.00  (1)

公开(公告)号：US20220136469A1

公开(公告)日：2022-05-05

申请号：US17429404

申请日：2020-02-13

Applicant: NIPPON STEEL CORPORATION ,  USUI CO., LTD.

Inventor： Taizo MAKINO ,  Masahiro YAMAZAKI ,  Tomohiko OMURA ,  Yuji ARAI ,  Osamu ENDO ,  Naoki SERIZAWA ,  Tatsuya MASUDA

IPC: F02M37/00 ,  C22C38/02 ,  C22C38/00 ,  C22C38/06 ,  C22C38/50 ,  C22C38/48 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/58 ,  C21D8/10

Abstract: A steel pipe for a fuel injection pipe has a chemical composition consisting of, by mass %: C: 0.17 to 0.27%, Si: 0.05 to 0.40%, Mn: 0.30 to 2.00%, P: 0.020% or less, S: 0.0100% or less, O: 0.0040% or less, Ca: 0.0010% or less, Al: 0.005 to 0.060%, N: 0.0020 to 0.0080%, Ti: 0.005 to 0.015%, Nb: 0.015 to 0.045%, Cr: 0 to 1.00%, Mo: 0 to 1.00%, Cu: 0 to 0.50%, Ni: 0 to 0.50%, V: 0 to 0.15%, and the balance: Fe and impurities. The metal micro-structure consists substantially of tempered martensite, or tempered martensite and tempered bainite. The hardness is within the range of 350 to 460 HV1. A lattice spacing of a (211) diffraction plane measured by CoKα characteristic X-ray diffraction is 1.1716 Å or less, and a half-value width of the (211) diffraction plane is 1.200° or less. The number density of cementite having a diameter of 50 nm or more is 20/μm2 or less.