Influence of TIG Process Parameters on the Microstructure and Hardness Property of AISI 430 Ferritic Stainless Steel Welds using Response Surface Methodology Approach

Authors: Musa AA, Dauda ET, Bello KA

DOI Info: N/A

ABSTRACT

In the present study, the effect of tungsten inert gas (TIG) welding process parameters on microstructural features and hardness property of AISI430 ferritic stainless steel welds was investigated using response surface methodology, based on the central composite design (CCD). The process parameters considered in this study were the welding current (I), welding speed (S) and argon flow rate (AFR). It was observed that all input variables considered had direct influence on the microstructure as well as the hardness property of the weldment. Microstructural results indicate ferrite structures with finely dispersed particles aligned in the cold rolling direction for the base metal. The microstructure of the weld metal with the optimized conditions revealed the presence of martensite structures along the grain boundaries as well as fine equiaxed grains within the fusion and heat affected zones of the weldment. The welding speed plays the major role on the hardness property followed by the welding current and the argon flow rate in that order. An empirical model was generated from the obtained response to predict the weld quality in terms of the hardness value. An optimized hardness of 307.10 HV was predicted at the welding current of 22 A, welding speed of 5 mm/sec and argon flow rate of 10 L/min. Confirmation test was performed to check the practicability of the developed model and the results obtained was in good agreement with the predicted value with average percentage error of 2.21% which is within the acceptable value for adequate model.

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