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ORIGINAL CONTRIBUTION

Fatigue Life Prediction of Dissimilar Metal Laser Weld Joints A. P. Tadamalle1 • Y. P. Reddy1

Received: 14 June 2019 / Accepted: 24 July 2020 Ó The Institution of Engineers (India) 2020

Abstract Fatigue failure of dissimilar metal weld structures occurs when it is subjected to fluctuating loads. The structures made of dissimilar metal weld joints were found in many industrial applications. This paper is aimed to estimate the fatigue life of 0.76 mm 304 L stainless steel and mild steel laser welds using energy balance equation and infrared camera. The laser welding experiments are conducted as per the L4 Taguchi’s method, and optimal process parameters were estimated using Taguchi approach. The weld joint prepared at optimal process parameters is considered for prediction of fatigue life. The fatigue tests are conducted by varying pretension load and keeping amplitude constant. The rise in temperature of the specimen is captured during the fatigue life test using infrared camera. The results obtained from this approach are in good agreement with the experimental results. This study helps to predict the fatigue life of the welds quickly based on rise in temperature information acquired during the initial stages of fatigue test. Keywords Fatigue life  Dissimilar metal  Infrared camera  Laser welding  Temperature

& A. P. Tadamalle [email protected] 1

Department of Mechanical Engineering, Sinhgad College of Engineering, Vadgaon (Bk), Pune 411041, Maharashtra, India

Introduction The weld structures subjected to fluctuating loads lead to the development of microcracks below the ultimate strength of the material. Stress developed during fatigue tests has a significant influence on strength of the welded joints, and hence, it is essential to consider induced stresses during fatigue life assessment of welds. The development of induced stresses depends on welding process parameters used. The induced stresses has an effect on tensile strength, hardness and weld bead geometry of low-carbon steel and 16MnCr5 alloy steels [1]. A study on P91 plates of 6 mm thick was conducted as per L9 orthagonal array design matrix and developed a trade-off between maximum weld penetration, minimum weld width and cross sectional area [2]. The effect of parameters on HAZ morphology, weldability, weld shape, strength, microhardness, porosity and characterization of partially and fully penetrated laser welds was tested and it was observed that the more variation in weld shape were found below 1700 W of power and 2 ms pulse duration regardless of welding speed. The greater microhardness is reported in the transverse direction as compared to the thickness and also blowholes were observed at the bottom of welds [3–6]. The coated S355 structural steel were analyzed for fatigue strength and revealed that the coating has negligible effect on fatigue life. The fatigue strength of laser weld joints depends on weld toe and root geometry [7, 8]. The impact resistance of the weld joints was studied to assess the influ