Optimization of tensile strength for heat treated micro-alloyed steel weldment

Welding and post weld heat treatment process variables play important roles in determining the quality of welds. Thus, to produce welded joints of desired microstructure with the requisite mechanical properties for optimal performance in service, the need for the analysis of the process variables requiring optimization to determine their influence on the response (output) is very vital. In this study, the optimal design approach was used to optimize the main influencing process variables of welding current, tempering temperature and holding time to determine their impact on the observable response (tensile strength). Through multiple regression analysis of the experimental data, the predicted response was expressed by the second-order polynomial equation in terms of coded values. The derived model was statistically analyzed to determine its significance and predictive capacity. The ANOVA results of the quadratic regression model used to fit the response showed that it is significant (P < 0.00001). The high coefficient of regression and adjusted regression coefficient values of 94.73% and 89.99% respectively, is an expression of the model degree of fitness. The model F-value of 19.99 greater than the P-value also attest to the model significant. Validation of the optimized predicted results revealed that they are in close consonant with the experimental results. This investigation has shown that the optimum values of welding current, tempering temperature and holding time for achieving optimal tensile strength of 258.141KN/m2 in the heat treated micro-alloyed steel weldment were 90.530 amp, 250.002 degrees C and 60.000 min respectively. Copyright (c) 2021 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Applied Research and Engineering 2021