Microstructural and Mechanical Characterization of Shielded Metal Arc Welded Dual Phase Steel Joints

Abstract

Dual Phase steels are widely used in industry for various reasons for their improved mechanical properties owing to their ferrite and martensite contents in microstructure and good formability at industrial scale to achieve final shape with good ductility. In this study, shielded metal arc welding experiments were performed in order to evaluate the metallurgically and mechanically the properties of Dual Phase steels obtained from plain carbon steel AISI 1010 by water quenching at intercritical temperatures. Martensite volume fraction (MVF) was related to the intercritical quenching temperature which defines the mechanical properties of Dual Phase steel. All the welding parameters were kept constant in order to get a value of heat input equals 1.37 KJ/mm for all weldments. Martensite was found to be predominated in the fusion zone and its hardness was the highest compared to base metal (BM) and heat affected zone (HAZ). The extent of ductile zone was found to be dependent on the MVF and reached over 1.2 mm wide. Tensile properties of weldments were deteriorated by 35% in ultimate tensile strength (UTS) and by 15% in elongation. The failure of all the welded joints was occurred in the SC zone, with the fractured surfaces of a dimple feature.