Investigation on the effect of post weld heat treatment on microwave joining of the Alloy-718 weldment

Abstract

In the present work, the butt joining of Alloy-718 (980 °C solution treated condition) was achieved in an industrial microwave oven using the principles of microwave hybrid heating (MHH) technique. The weldment reveals perfect diffusion bonding between base materials through fully melting of powder particles. The fabricated weldment was heat treated with standard heat treatments such as direct aged, 980 °C solution treated and aged, and solution treated at 1080 °C and ageing. The microstructural behaviors of all weldment were investigated along with their mechanical properties such as microhardness, tensile, and flexural strength at room temperature. The improvement in mechanical properties of post heat treated weldment was observed due to the dissolution of the Laves phase and precipitation of coherent precipitates in the fusion zone microstructure. The microhardness in the fusion zone of 1080 °C solution treated and aged weldment was higher among all welded condition due to complete Laves phase dissolution after this treatment. The flexural and tensile strength was higher at 980 °C solution treated and aged weldment among all welded condition.