Development of an improved steel for pipe fittings

Abstract

The requirements for steels for pipe fittings include a move to lower levels of carbon equivalent (CEV), improved strength, increased thickness, and improved weldability. The work on the development of a new pipe-fittings steel, untertaken within BSC, is described from the early laboratory casts through pilot-scale work to the production and assessment of a commercial cast. The new steel has a low value of proof stress in the normalized condition which, on tempering, is changed to a high level of yield stress coupled with good levels of toughness. X60 properties can be achieved with a target CEV of 0·47. The strength of the steel is not greatly affected by normalizing temperature and tempering temperature, thus providing the fabricator with a flexible process route.