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Ferritic stainless steel (FSS) is distinguished by their ferrite phase with BCC structure. FSS is iron based alloy with 10.5% to 30% chromium along with small amount of alloying elements. This steel remains stable at room temperature till it reaches its melting point (Robert G. Nooning, 2002). FSS has attained a new milestone in the last few decades by covering 30% of total market share (Amuda, Akinlabi, & Mridha, 2016). This increased popularity is due to its low price and stress corrosion resistance properties in chloride and caustic environment (Anttila, Karjalainen, & Lantto, 2013). This steel also gives considerable cost saving benefits over austenitic steel (Amuda & Mridha, 2013). Its applications can be found in wide variety of areas such as muffler, catalytic convertor of automobile exhaust system, different parts of railway wagons, drums of washing machine, frames of busses etc. (Dan, Mohd Sabri, Hussain, & Mohebbi, 2018; Mamphekgo, Matjeke, & Pillay, 2018).
Though ferritic stainless steel has been used in wide applications, still its use is restricted due to its low weldability (Taban, Deleu, Dhooge, & Kaluc, 2009). It suffers from severe grain growth in the regions exposed to heat during welding operations. This grain coarsening leads to adverse effects on its mechanical and microstructural properties (Kah & Dickinson, 1981). Amuda and Mrida (Amuda & Mridha, 2010) confirmed that high heat input with slow cooling rate during welding, gave ample time for the grains to elongate, hence promotes grain coarsening. Mohandas et al. (Mohandas, Madhusudhan Reddy, & Naveed, 1999) compared the 3mm thick ferritic steel weld joints made by the gas tungsten arc welding and shielded metal arc welding process. Authors concluded that welds made by gas tungsten arc process gave higher strength and ductility than shielding metal arc process owing to its less heat input. Lakshminarayanan et al. (Lakshminarayanan, Shanmugam, & Balasubramanian, 2009) used 3 types of autogeneous arc welding processes to weld 4 mm thick rolled AISI 409M plate and made a comparison in terms of microstructural and mechanical properties. They concluded that weld joints prepared from pulsed arc welding process exhibits higher mechanical properties and finer grains structure due to less heat input during welding than the weld joints made from continuous current arc welding process and plasma arc welding process. Taban et al. (Taban, Dhooge, & Kaluc, 2009) used plasma arc welding process to weld 12 mm thick ferritic stainless steel plates. Authors concluded that grain coarsening occurred at weld zone and heat affected zone which reduced the impact toughness in comparison to base metal. Mukherjee et al. (Mukherjee, Dutta, Kanjilal, Pal, & Sisodia, 2015) concluded that pulsed mode welding process reduced the amount of dilution and enhanced the weld zone grain structure. The hardness of weld metal was higher than the heat affected zone. Gupta et al.(Gupta, Raja, Vashista, & Yusufzai, 2018) investigated the effect of heat input in AISI 409L ferritic steel and concluded that the grain size is inversely proportional to the microhardness, ultimate tensile strength and yield strength.