Patent ID: 9598746
Date: 2017-03-21
CPC Classifications: C21D,C22C

Claim:
1. A seamless steel pipe, comprising: a steel composition comprising: wherein the wall thickness of the steel pipe is greater than or equal to 8 mm and less than or equal to 35 mm; wherein the steel pipe is processed to have a yield strength greater than 550 MPa (80 ksi) and wherein the microstructure of the steel pipe comprises martensite in a volume percentage greater than or equal to 60% and lower bainite in a volume percentage less than or equal to 40%; wherein the microstructure of the steel pipe does not include upper bainite nor ferrite; wherein the steel pipe has a ductile to brittle transition temperature less than −70° C.; and wherein the steel pipe does not exhibit failure due at least in part to stress corrosion cracking after about 720 hours when subjected to a stress of about 90% of the yield stress and tested according to National Association of Corrosion Engineers standard TM0177.