Patent ID: 7862667

Claim:
A steel composition, comprising: carbon (C) between about 0.2 and 0.3 wt. %; manganese (Mn) between about 0.1 and 1 wt. %; silicon (Si) between about 0 and 0.5 wt. %; chromium (Cr) between about 0.4 and 1.5 wt. %; molybdenum (Mo) between about 0.1 and 1 wt. %; niobium (Nb) between about 0 and 0.1 wt. %; aluminum (Al) between about 0 and 0.1 wt. %; calcium (Ca) between about 0 and 0.01 wt. %; boron (B) less than about 100 ppm; titanium (Ti) between about 0 and 0.05 wt. %; tungsten (W) between about 0.1 and 1.5 wt. %; vanadium (V) between about 0 and no more than about 0.05 wt. %; copper (Cu) between about 0 and no more than about 0.15 wt. %; oxygen (O) less than about 200 ppm; nitrogen (N) less than about 0.01 wt. %; sulfur (S) less than about 0.003 wt. %; and phosphorus (P) less than about 0.015 wt. %; wherein the average packet size, d packet of the steel composition, the precipitate size of the steel composition, and the shape factor of the precipitates are selected to improve the sulfur stress corrosion resistance of the composition; wherein the average packet size, d packet of the steel composition is less than about 3 Î¼m; wherein the composition possesses precipitates having a particle diameter, d p , greater than about 70 nm and which possess an average shape factor of greater than or equal to about 0.62; and wherein the shape factor is calculated according to 4AÏ€/P 2 , where A is area of the particle projection and P is the perimeter of the particle projection.