Effect of minor elements on weldability of nickel base superalloys

The present state of knowledge on the effects of C, B, S, and P on the weld ability of Ni base superalloys is reviewed. Consideration is also given to the effects of Mg and the rare earths on weldability, though the data are s parse and the manufacturing route often not defined. From the analysis, B i s considered to be the most detrimental element to the weldability, with le sser effects from C and S. The data on P are limited, but recent results sh ow that P has a variable effect on weldability, being most detrimental in l ow C alloys (0.01 wt-%), and less of a problem in C levels > 0.03 wt-% and above. Consideration is also given to the effects of heat treatment in infl uencing solute segregation to the grain boundary and on grain growth. The p otential effects of two or more elements on grain boundary microchemistry a nd its effects on weldability are also discussed.