Method for manufacturing an ultra-high strength cold-rolled steel sheet with desirable delayed fracture resistance
US5542996A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 4, 1994 |
| Grant date | Aug 6, 1996 |
| Priority date | — |
| Expiry date | Mar 4, 2014 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC22C38/04
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A method for manufacturing an ultra-high-strength cold-rolled steel sheet having desirable delayed fracture resistance, which comprises: preparing a material consisting essentially of 0.1 to 0.25 wt. % carbon, up to 1 wt. % silicon, 1 to 2.5 wt. % manganese, up to 0.020 wt. % phosphorus, up to 0.005 wt. % sulfur, 0.01 to 0.05 wt. % soluble aluminum, 0.0010 to 0.0050 wt. % nitrogen, optionally at least one of Nb, Ti or V, optionally at least one of Cu, Ni, B, Cr or Mo, the balance being iron and incidental impurities; subjecting the material to a hot rolling, a pickling and a cold rolling to prepare a cold-rolled steel sheet; and subjecting the cold-rolled steel sheet to a continuous heat treatment which comprises: subjecting the cold-rolled steel sheet to a soaking treatment at a temperature of Ac.sub.3 to 900.degree. C. for 30 seconds to 15 minutes, quenching the cold-rolled steel sheet at a quenching rate of at least 400.degree. C./second from a temperature of at least a lower limit temperature (T.sub.Q) for starting quenching as expressed by the following formula to a temperature of up to 100.degree. C.: T.sub.Q (.degree.C.)=600+800.times.C+(20.times.Si+12.times.Mo+13.times.Cr)-…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.