Determination of the microstructure and mechanical properties ofgas metal arc welded AISI 430 ferritic stainless steel plates

Ferritic stainless steels contain Cr as the main alloying element and display very good corrosion resistance even at high temperatures. These stainless steels are widely used in manufacturing of products such as hot water tanks, food processing industry, machinery and manufacturing industry, dental and medical devices, and kitchenware. The most characteristic difficulty encountered in fusion joining of this type of stainless steels is the grain coarsening in the heat affected zone. Furthermore, carbide precipitation at grain boundaries in the heat affected zone may also be observed if the heat input used in the welding process is extremely high. Thus, it is required that the heat input should be kept low in order to successfully join these steels by conventional fusion welding methods. The determination of the effect of heat input on microstructural evolution in the weld region and the mechanical properties of the welded joints in gas metal arc welding of AISI 430 ferritic stainless steel plates was aimed in this study. To that end, AISI 430 ferritic stainless steel plates with a thickness of 5 mm were joined using different heat input values. The microstructures in the weld region and mechanical properties of the welded plates were investigated by detailed optical microscopy investigations, micro-hardness measurements and tensile tests. It was determined that the hardness increased in the weld region of the welded plates and the joints displayed similar tensile strength levels similar to that of the base plate. Moreover, it was observed that increasing heat input negatively affected the toughness of the heat-affected zone.