INVESTIGATIONS ON MICROWAVE JOINING OF 21-4-N NITRONIC STEEL

Abstract

In recent years, scientists and technocrats have been exploring new material processing methods to process advanced materials. In this work, a novel and emerging method of joining i.e. microwave joining has been employed to join 21-4-N nitronic steel plates and further characterize using UTM, FE-SEM, EDS, XRD and Vickers micro-hardness tester. Microwave hybrid heating (MHH) mode has been used to achieve fusion of 21-4-N nitronic steel plates. A simple fixture was made to perform microwave joining inside a multi-mode microwave applicator operating at 2.45 GHz frequency and 900 W power. Charcoal, nickel powder (⁓size 20 μm), and clay bonded SiC plate was used as susceptor, interface material and separator, respectively. Micrographs of joints obtained shows complete solubility of interface material and finer microstructure in the weld zone. Mechanical characterization of joint revealed that the strength of the joint is approximately 61 % of the base material and hardness obtained of the joint is approximately 80 % of the base material. Fractography analysis of the joint revealed that joint failed due to the ductile as well as brittle mode.