Method for making high-strength high-toughness martensitic stainless steel seamless pipe
US6846371B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 23, 2002 |
| Grant date | Jan 25, 2005 |
| Priority date | — |
| Expiry date | Aug 23, 2022 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB21B2201/16
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A method of producing a high-strength high-toughness martensitic stainless steel seamless pipe which includes heating a martensitic stainless steel raw material to an austenitic range and subjecting the raw material to piercing and elongating to form an original pipe. The original pipe is cooled to form a structure substantially composed of martensite in the original pipe. The original pipe is reheated to a temperature in the dual-phase range between the Ac1 transformation point and the Ac3 transformation point, and is subjected to finishing rolling at an initial rolling temperature T (° C.) between the Ac1 transformation point and the Ac3 transformation point. The original pipe is then cooled to form a processed pipe. The processed pipe is tempered at a temperature below the Ac1 transformation point. The reduction in area R in the finishing rolling step may be in the range of 10% to 90%, and the initial rolling temperature T and the reduction in area R may satisfy the relationship 800≦T−0.625R≦850.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.