Effects of chromium and tungsten on sulfide stress cracking in high strength low alloy 125 ksi grade casing steel

摘要

Chromium and tungsten contents were varied to produce three different 125 ksi grade casing steels, and their sulfide stress cracking (SSC) behaviors were evaluated using double cantilever beam testing. The effects of chromium and tungsten on the SSC resistance were clarified by microstructure analysis and hydrogen permeation test. Reducing the chromium content and adding tungsten significantly increased the number of irreversible traps and decreased the proportion of the E3 boundaries and high-angle grain boundaries. Moreover, the addition of tungsten led to the reduction of hydrogen permeability and diffusivity, resulting in the enhancement of SSC resistance.