The influence of minor elements on the weldability of an INCONEL 718-type superalloy

The effect of the minor elements C, B, and P on the weldability of the INCONEL 718 alloy was studied. Wrought alloys containing systematic additions of the three minor elements were evaluated by thermal simulation and by electron-beam welding. The ductility recovery temperature from the thermal simulation experiments and the microfissuring behavior in the heat-affected zone (HAZ) of the electron-beam samples were used to evaluate the effect of minor elements on weldability. Carbon was found to have minimal effect on weldability, whereas, as previously observed, B has a significant negative impact on weldability. The element P, in combination with B, was extremely detrimental to weldability, but C mitigated the harmful effects of B and P, both individually and in combination. The effect of the minor-element additions has been explained in terms of site competition OF segregating species on grain boundaries.