Residual Stresses in Bimetallic Weld Joint With Varying Buttering Layer Thickness

The use of bimetallic weld joints is widespread in thermal and nuclear energy generation. It is evident from literature survey that the weld and ferritic steel HAZ region of bimetallic joints are prone to failures. The failures can be attributed to the generation of residual stresses in bimetallic welds. A typical bimetallic weld joint, representing a joint being tested for use in Indian Nuclear Reactors was fabricated between SA 516 Grade 65 and 304 austenitic stainless steel with and without the use of SS 309 L buttering layer. The buttering layer thickness was varied and surface and subsurface residual stresses were assessed using the hole drilling technique and neutron diffraction measurements. It was found that the SS 309 L buttering layer with thickness of around 6 mm employed in the bimetallic weld joint reduces the surface and sub-surface residual stresses in the critical region (ferritic steel HAZ) of the bimetallic weld joint.