Effect of Heat input on Micro Hardness and Metallurgical Properties of Shield Metal ARC Welded Duplex Stainless Steel

Abstract

The work was carried out to the effect of heat input on the hardness and metallurgical properties of shield metal arc welded of duplex stainless steel. Three specimen A, B and C with heat input combinations designated as low heat A (0.675 KJ/mm), medium heat B (0.860 KJ/mm) and high heat C (1.094 KJ/mm) and the weld joints made using these three combinations were subjected to observe the changes in thermal condition caused by variation of heat input can affect the metallurgical properties and the hardness of the welded joint. The result achieved from this research shows that the joints made using low heat input exhibited having more hardness than those welded with medium and high heat input. Heat affected zone of welded joint made with medium heat input has austenitic ferritic grain structure with some patchy austenite provide higher harness of the welded joint. Significant grain coarsening was observed in the heat affected zone (HAZ) of medium and high heat input welded joints, whereas low heat input welded joint shows the fine grain structure in the heat affected zone with small amount of dendritic formation and equiaxed grain structure where inner zone indicates slowly cooled grains in the direction of heat dissipation.