Feasibility study on joining of multi-layered W/Cu-CuCrZr-SS316L-SS316L materials using vacuum brazing

[Display omitted] •A study on the joining of tungsten, copper, copper alloy, and stainless steel in a single step process using vacuum brazing with suitable filler materials has been reported.•The multi-layered, brazed joints have been ultrasonically examined to check the integrity of the joint interfaces. Ultrasonic testing on the brazed joints provides the overall information/signatures about well-bonded and partial bonded interfaces.•Microstructural examination has been performed to determine the filler material interaction with base materials. Good Interaction of NiCuMn filler with Cu and CuCrZr material and Interaction of TiCuNi filler with SS and CuCrZr are observed. Non-uniformity in the joining of SS316L to SS316L is observed.•Mechanical tests such as micro hardness and shear strength measurement have been conducted. Shear strength measurement of the multi-layered brazed joint, the Cu-CuCrZr joint interface exhibited the maximum shear value of 175 MPa, followed by the Cu to SS316L brazed joint with shear value of 150 MPa and the SS316L to SS316L interface exhibited the shear strength of approx. 73 MPa. The W-Cu interface joint exhibited a shear strength of approx. 22 MPa due to fracture in W side. The plasma facing component (PFC) of an ITER-like tokamak requires the multi-layered joining of dissimilar materials. The multi-layered joining employs various materials such as tungsten, copper, CuCrZr and SS material. These multi-layered components are expected to handle the heat load up to 10MW/m2 during the tokamak operation. In the case of thermal loads during tokamak operation, the mismatch in thermal expansion of such dissimilar materials results in thermal stresses at the joint interfaces that can affect the operational performance of the component. In order to join the materials, the vacuum brazing technique has an advantage over welding as it generates less heat affected zone (HAZ) in the parent materials and does not melt the base material. In this paper, a study on the joining of tungsten, copper, copper alloy, and stainless steel in a single step process using vacuum brazing with suitable filler materials has been reported. The multi-layered, brazed joints have been ultrasonically examined to check the integrity of the joint interfaces. Microstructural examination has been performed to determine the filler material interaction with base materials. Mechanical tests such as micro hardness and shear strength measurement have also been conducted.