Optimization of pulsed TIG cladding process of stellite alloy on carbon steel using RSM

Stellite 6 is a cobalt-base alloy which is resistant to wear and corrosion and retains these properties at high temperatures. The exceptional wear resistance of Stellite 6 is mainly due to the unique inherent characteristics of the hard carbides dispersed in a Co–Cr alloy matrix. In this study, pulsed tungsten inert gas (TIG) cladding process was carried out to deposit Stellite 6 on plain carbon steel plate. The beneficial effects of this cladding process are low heat input, low distortion, controlled weld bead volume, less hot cracking tendency, less absorption of gases by weld pool and better control of the fusion zone. The dilution effect is a key issue in the quality of cladded layers and, in this regard, the pulsed current tungsten inert gas (PCTIG) was performed to decrease excess heat input and melting of substrate. This paper deals with the investigation of the hardness and dilution ratio by experimental study and mathematical modeling. The experiments were conducted based on four-factor, five-level central composite rotatable design. The second-order regression method was developed to study the correlations. The developed models were checked for their adequacy and significance by ANOVA analysis and confirmation tests were carried out to check the accuracy of predicted values.

► This study is useful to optimize the welding process variables in order to control the heat input and cooling rates such that the hardness and dilution of the clad could be estimated.
► Central composite rotatable design technique with five-level, four-factor full-factorial design matrix and mathematical models was used to predict hardness and dilution of pulsed gas tungsten arc weld cladding of stellite6 on carbon steel with high accuracy.
► The welding current is an effective parameter affecting heat input and melting. In this regard, it is the most important process parameter which influences the dilution. Increase welding current leads to increase in dilution percentage and vice versa. The effect of percentage on time is less important when compared to the other factors.
► The results predicted by mathematical models were close to those obtained by experiments. The confirmation tests also indicated high correlation between the mentioned values.
► All of the chosen pulse GTAW parameters were significant and showed a noticeable influence on clad dilution.