Effect of brazing temperature, filler thickness and post brazing heat treatment on the microstructure and mechanical properties of W-Eurofer joints brazed with Cu interlayers

Abstract

One special issue still unresolved for the development of the future fusion power plants is the necessity of finding joining technologies between W and Eurofer. In this paper, the use of copper as filler material to join W to Eurofer is explored. By that, the effect on the brazeability of different process parameters such as filler thickness, brazing temperature and post-brazing heat treatment has been evaluated. The results indicated the consecution of high continuity interfaces where tungsten is involved in the formation of different reaction layers. The mechanical properties indicated that the strength of the joints are highly influenced by the different studied parameters having found that brazing temperature of 1135 °C is more adequate (309 MPa). The application of a tempering treatment to reduce the thermal stress of the steel produces a softening effect in the joint reducing the strength down to 148 MPa, giving rise to joints that are more ductile.