Effect of post bonding heat treatment on the local strain evolution of transient liquid phase bonded RAFM steel

Abstract

In this paper, post bonding heat treatments to transient liquid phase bond reduced activation ferrite/martensitic steel were conducted, with a Fe–Si–B amorphous foil as the interlayer. The results show that, the post bonding heat treatments decreased the strength difference between different regions of the transient liquid phase bonded joint and altered the shape and the amount of Cr2B along the interface between the diffusion affected zone and base metal. In particular, it is found that the tensile fracture position of the as-bonded joint has been altered by post bonding heat treatment, from the interface between the diffusion affected zone and the base metal to where inside the base metal. In order to unveil such deformation differences between transient liquid phase bonded joints with and without post bonding heat treatment, digital image correlation method was adopted to study the influence of post bonding heat treatment on the local strain evolution of transient liquid phase bonded joint from both macro- and micro-scale. The non-uniform strain distribution upon the nominal surface of the tensile samples during deformation showed that, the strain of the as-bonded joint was always localized at the interface of the diffusion affected zone, resulting brittle fracture eventually. While for the joint after post bonding heat treatment, the strain localization gradually transferred from the interface to the base metal during the tensile test, which is attributed to the changing deformation resistance of these regions during straining.