A Discussion of the Effects of Gettering Sulfur as Particles of Carbosulfides on the Toughness of Ultra-high Strength Steels

摘要

The work of Maloney demonstrated that for HY180 steel gettering sulfur as titanium carbosulfide could lead to much higher levels of toughness than when the sulfur is gettered as MnS or as lanthanum oxy-sulfide. This effect was attributed to particles of titanium carbosulfide being much more resistant to void nucleation than particles of MnS or lanthanum oxy-sulfide. This work considers first the effect of gettering sulfur as titanium carbosulfide on the toughness of AF1410 steel, a steel similar to HY180 but having higher yield strength. Second, this paper considers the extent to which other alloying additions which also form carbosulfides improve the toughness of AF1410 steel. Niobium and zirconium form carbosulfides having the same crystal structure as titanium carbosulfide. Additions of niobium and of zirconium have been made to AF1410 and the toughnessess of these alloys determined. The results indicate that titanium additions substantially improve the toughness of AF1410 and that additions of niobium may be even more effective than titanium additions in improving toughness but that zirconium additions are less effective than additions of titanium or niobium.