STUDY OF WELD JOINT CHARACTERIZATION USING MICROWAVE HYBRID HEATING

Abstract

One of the connecting processes that have the most potential that has developed is welding. Throughout their growth, many welding techniques have been developed. Any nation's manufacturing industry is crucial to its economic growth, but it also uses more than 30% of the nation's energy resources. Technologists, researchers, and academics are always trying to process materials efficiently in order to lower manufacturing costs and conserve energy in order to tackle such scenarios. Due to increased energy use, pollution levels, low productivity, and the production of more flaws in manufactured components, traditional manufacturing techniques are becoming obsolete. To lower production or manufacturing costs, processing times, and to improve product quality, alternative processing methods are necessary. The development of sustainable, green, and energy-efficient processing techniques is the main emphasis at the moment. Therefore, it is crucial for researchers to look for alternate processing methods and procedures that might potentially compensate for or lessen the shortcomings of current ones. The established procedures are anticipated to generate better-quality goods at an efficient processing cost while reducing CO2 or other undesired hazardous gas emissions and improving energy efficiency. There has been a lot of work published on the microwave joining of bulk metals and the coating of metallic-based powders on metallic surfaces. The researchers were inspired to investigate the possibilities of microwave heating in powdered metal joining techniques since the joining and cladding were accomplished with partial melting of metallic powders. However, the majority of the research focused on the sintering of metallic powders and gave researchers a chance to explore the possibility of using microwaves to melt metallic-based powders. In the current study, stainless steel 304 (40x20x3) mm is joined using microwave radiation, and the impact of various process parameters on the mechanical characteristics of welded butt joints is examined. As a microwave applicator, a domestic IFB microwave oven operating at 2.45 GHz and 900 W of fixed frequency and power respectively is employed with hybrid heating technique. v Page v Tensile strength, microhardness, and surface temperature were chosen as the output process parameters that are to be optimised, while varied sizes of nickel powder, variation in slurry by weight, and welding time were chosen as the input process parameter. Response surface methodology (RSM), which is based on statistics, was used to conduct the tests, evaluate the findings, and improve the settings. The design matrix for welding the butt joints was created using rotatable central composite design with face centered (CCDFC). The matrix was created using three factors, each with three levels. Twenty trials in all, including the centre points, were carried out using a standard microwave oven. An ANOVA (analysis of variance) was used to analyse how the process factors affected the weldments mechanical characteristics. The relationship between the input parameter and the outcomes has been demonstrated empirically. This model is capable of predicting both the primary impacts and the combined effects of the two elements that make up the selected welding process parameters. The X-Ray Diffraction patterns (phase analysis), mechanical characteristics (microhardness, tensile strength), microstructural characterizations (using optical microscope and field emission scanning electron microscopy), and surface temperature measurement were all used to evaluate the generated joints. Optical microscopy and a field emission scanning electron microscope (FESEM) are used for microstructural characterization. Tensile testing and microhardness testing were done for mechanical characteristics. An infrared gun is employed to determine the surface temperature of the joint region. Overall, the findings supported the assertion that metal components were effectively joined using microwave radiation. Using the CCFCD approach, the ideal values for the input variables welding time, particle size, and slurry weight were found. The impact of welding time (microwave) was greatest, followed by powder particle size and weight of the slurry material. As welding time and slurry weight increases, tensile strength, microhardness, and surface temperature of the welded material all increase, but as particle size increases, all three output variables decreases. The greatest values of tensile strength (501MPa), microhardness (454Hv), and surface temperature (9320C) in the welded region are obtained using experimental settings of 13 min. of welding time, 3 g of slurry weight, and 5 µm of powder size. The high microwave heating caused different intermetallic phases to develop, as demonstrated by the XRD examination of welded joint. Formation of Carbides (Cr3C2 and Fe2C) and phases of iron and nickel (NiSi and FeSi) are detected at peak in the research. Microstructure and FESEM study findings showed that microwave processing generates superior microstructures for the highest values of welding time and slurry weight and the lowest value of powder size with fewer flaws when compared to other input values. Absolute fusion of flaring surfaces and appropriate metallurgical bonding with metal are achieved by volumetric and uniform heating throughout the joint. Both brittle and ductile modes of failure were seen during the joint fracture. According to the Energy Dispersive Spectroscopy (EDS) analysis, the joint section contains higher chromium and carbon content for the maximum output values.