Process for producing high-strength seamless steel pipe having excellent sulfide stress cracking resistance
US5938865A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 5, 1998 |
| Grant date | Aug 17, 1999 |
| Priority date | — |
| Expiry date | Feb 5, 2018 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB21B19/04
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
A process for producing a seamless steel pipe wherein pipe manufacturing steps and the heat treatment steps are carried out in one production line. The properties of the pipe are comparative or superior to those of the pipe manufactured in the conventional reheating, quenching and tempering process. The process is characterized by using the billet of a low alloy steel containing C: 0.15-0.50%, Cr: 0.1-1.5%, Mo: 0.1-1.5%, Al: 0.005-0.50%, Ti: 0.005-0.50% and Nb: 0.003-0.50%, and comprising the following steps (1) to (5). PA1 (1) hot rolling with 40% or more of cross sectional reduction ratio, PA1 (2) finishing the hot rolling in a temperature range of 800-1100.degree. C., PA1 (3) putting the manufactured steel pipe promptly in a complementary heating apparatus after the finish rolling, and complementarily heating at the temperature and time satisfying the following formula (a). PA1 (4) quenching the steel pipe immediately after taking out of the complementary heating apparatus, and PA1 (5) tempering the pipe at a temperature not higher than the Ac.sub.1 transformation point as the last heat treatment. EQU 23500.ltoreq.(T+273).times.(21+log t).ltoreq.26000 (a) where, T (.degree.C.) i…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.