Hot-rolled steel sheet for heavy-wall, high-strength line pipe, welded steel pipe for heavy-wall, high-strength line pipe, and method for producing the welded steel pipe
US11377719B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 6, 2017 |
| Grant date | Jul 5, 2022 |
| Priority date | — |
| Expiry date | Jun 17, 2039 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16L1/123
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A hot-rolled steel sheet for a heavy-wall, high-strength line pipe, the steel sheet having a chemical composition including, in mass %, C: 0.02 to 0.20%, Mn: 0.80 to 2.10%, Si: 0.01 to 0.50%, P: 0.034% or less, S: 0.0050% or less, Nb: 0.01 to 0.15%, Ti: 0.001 to 0.030%, and Al: 0.001 to 0.080%, the balance being Fe and incidental impurities, the steel sheet having a microstructure in which a main phase is a continuous cooling transformation structure and in which {001}α grains in a plane whose normal direction is the sheet width direction constitute an area fraction of 10% or less and have a combined size of 10 μm or less, wherein the steel sheet has a tensile strength of 520 MPa or greater, and, in a drop weight tear test, a temperature at which a percent ductile fracture reaches 85% is −25° C. or lower.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.