Hardness and Thermal Analysis in Welded Butt Joint of Hybrid Aluminium (LM25) Metal Matrix Nano Composite Cylindrical Rod using TIG Welding Process

In this paper a new attempt is made by optimization of welding parameters in welded butt joint the Hybrid LM25 Aluminium Metal Matrix Nano Composite Cylindrical Rod Samples. Here Hybrid LM25 Aluminium metal matrix nano composite (AMMNC) is made by using stir casting method. Here Base metal LM25 Aluminium alloy is adding the reinforcing matrix as 2% of nano Silicon carbide particles along with 3% of nano alumina for producing Hybrid AMMNC Samples. Joining of this Hybrid AMMNC samples are done by using TIG welding, due to its low cost and good quality of welds among arc welding processes these reinforcements are dispersed as nano particles to get a benefit of enhancing in their strength. While joining of hybrid AMMNC cylindrical rod butt joint by using TIG welding process. To optimize the TIG welding parameters such as Welding pulse current, Arc voltage and Shielding gas flow rate experiment is designed using One-Factor Multilevel-Categorical Factor technique. By conducting the experiment, effect of welding parameters such as welding pulse current, Arc Voltage and shielding gas flow rate on weld centre micro hardness is evaluated. Regression equation is developed using Design-Expert version 11 statistical software to predict the weld centre micro hardness. Correlation co-efficient (r2) showed 0.95 and error % showed less than 5% which means the regression equations are developed in the most consistent. Empirical model is developed to optimize the pulsed current parameters of welding is also performed using Design Expert - statistical software. Optimized values for pulse on welding time, arc voltage and shielding gas flow rates are 120A, 21V and 12 l/m respectively. Optimized predicted value of weld centre micro hardness has been observed as 100HV. Trial runs are performed for optimized PCTIG welding condition to check the consistency of the model, which resulted only 5% of deviation between experimental values and predicted values. It shows the optimized welding pulsed current, Arc Voltage and Shielding gas flow rate parameters resulted in higher micro hardness value which implies that strength of the weld is increased with respect to optimize welding parameters. In addition to investigate the temperature distribution in optimized Hardness value of welded AMMNC sample. Then heat fusion in the size and distribution of heat source, the travel speed, the heat conduction in the welding direction and the surface heat loss during welding are considered. A numerical scheme is developed to solve the three dimensional problem. With the help of a mathematical model, the effect of welding parameters such as heat input of the weld, preheating of the work piece and moving velocity of heat source on weld penetration in welded AMMNC cylindrical rod samples are discussed. The steady-state temperature profiles of the welded AMMNC samples are solved by finite difference method. In addition, a thermal experiment such as Heat Flux Differential Scanning Calorimeter Experiment is conducted to verify the theoretical results and Numerical results in ANSYS software. The predicted values from the proposed model are compared with the experimental data of optimized welded AMMNC samples.