Composition optimization of high-strength steels for sulfide stress cracking resistance improvement

With the development in the recent years of deep and sour wells, the mechanical properties of the drill collars tend to increase so that a higher sensitivity to sulfide stress cracking (SSC) is evidenced. In order to improve the behaviour of high-strength steels for drill collar in sour environment, the effect of a slight modification of the composition of a standard grade has been studied. Based on a literature review, different alloying elements have been selected and their influence on the SSC resistance of an existing commercial grade was evaluated. The results are discussed based on hydrogen permeation in sour environment.