Roles of Composition and Microstructure in Sulfide Cracking of Steel

Abstract

The sulfide cracking behavior of a number of carbon and low alloy steels is described. Susceptibility to sulfide cracking is shown to depend primarily on microstructure. Steels with uniform, spheroidized carbides in a ferrite matrix have the greatest cracking resistance at any given strength level. The presence of untempered martensite in the microstructure drastically reduces cracking resistance. Lamellar carbides resulting from either normalizing and tempering or isothermal transformation give rise to cracking resistance intermediate between steels fully quenched and tempered and steels containing untempered martensite.