Torsion strength of TIG welded similar and dissimilar metal joints of ASME SA213 Gr.T11 and BS3059:1987 PT1 ERW320

Tungsten Inert Gas (TIG) welding has been learnt to be the most widely used technique among the fusion welding techniques. Welding of different components of boilers is preferably accomplished by TIG welding, due to the process capabilities of the technique to produce sound joints, even in case of Dissimilar Metal Joints (DMJ). DMJs owing to the techno-economic advantages, find vast area of application especially in boiler fabrication industry. It has been learnt that the quality of welded joints is signified by mechanical properties of the joint. The present paper is focused on the behavioural aspects of similar and dissimilar metal joints of ASME SA 213 GR. T11 and BS 3059:1987 PT 1 ERW 320, the boiler steam tube materials, prepared by TIG welding under torsional loading. It has been observed that the dissimilar metal joint has performed better than the individual similar metal joints under torsional loading by achieving 85% of the torsion strength of one of the parent metal, whereas in the case of individual similar metal joints of ASME SA213 Gr. T11 and BS3059:1987 PT1 ERW320, 78% and 68% of the torsion strength of respective parent metals has been observed. ANOVA statistics have validated the existence of significant impact of input process variables on the output quality measure of the welded joint at 95% level of confidence. The predictive models for optimum torsional strength have been proposed by regression analysis.