Development of electron beam welding procedure for Nb-1Zr-0.1C alloy

Niobium is one of the most useful and widely used refractory metals. It can be worked to achieve a wide range of strength and elasticity, has the least density among refractory metals and possess superconducting and nuclear properties. Because of such properties, it finds applications in electrolytic capacitors, superconducting alloys, aircraft gas turbines, vacuum tubes and structural material in nuclear reactors. Refractory metals and alloys are capable of withstanding environments that are aggressive in terms of radiation, temperature, corrosion and stress for prolonged period of time. Nb-1Zr- 0.1C is one of the most promising refractory metal alloys having an excellent combination of high temperature properties like, high melting point (∼2500 °C), adequate high temperature strength (∼200 MPa) and creep strength for long duration, better compatibility for alkali liquid metal, resistance to thermal shock and radiation and low DBTT. This paper describes the development of electron beam welding procedure for Nb-1Zr-0.1C alloy. Welding parameters were developed by taking number of bead on plate welding trials. Weld bead was characterized by metallography and different zones of the weld bead were identified and studied. Weld quality was evaluated by both optical and electron microscopy. Microhardness profile across the width of the weld was generated. The results of the welding trials and the tests performed on the welds and the major observations and conclusions drawn from the experience of welding Nb-1Zr-0.1C alloy will also be discussed in this paper