Autogenous Tungsten Inert Gas Welding of 430 Ferritic Stainless Steel: The Effect of Inter-pass Temperature on Microstructure Evolution and Mechanical Properties

Effect of inter-pass temperature on the microstructure evolution and mechanical properties of AISI 430 ferritic stainless steel welded by autogenous tungsten inert gas (TIG) technique was investigated. The relationship between the structure and the property of the weldments with inter-pass temperature and without inter-pass temperature is elaborated in this study. Microstructure studies depicted the presence of martensite in the weld metal and some parts of the heat affected zone (HAZ). Increasing inter-pass temperature resulted in higher amount of martensite both in the weld metal and in the HAZ. In addition, high inter-pass temperatures resulted in large HAZ width and grain growth which in turn led to poor tensile strength and ductility of the weldments. An optimum inter-pass temperature of 150 °C provided the best mechanical properties. However, it was inferred that when it is not possible to have a precise control on inter-pass temperature during manufacturing AISI 430 joints, it is better to complete welding without applying inter-pass temperature in order to at least keep tensile strength and ductility of the weldments.