Metallurgy and application of ASTM A707 forgings

The 50 year history of copper ageing steels is reviewed. Early developments were focused on linepipe and fittings whereas more recent interest has been in heavy section ultra high strength forgings. The metallurgical basis for the original steels is presented and compared with the approaches used for extending the concept to forgings. Modifications include higher nickel contents and niobium-molybdenum age hardening to complement the effects of copper. Mechanical property and weldability data are presented along with test results for sour service variants of the forgings. (AU)