CRITICAL ANALYSIS OF MATERIAL BEHAVIOUR IN WELDED PLATES OF AISI 0.2%-C STEEL UNDER AS-WELDED, QUENCHED AND ANNEALED CONDITIONS

AISI 1020 grade of steel is well known for its good combination of high strength and fair ductility. Therefore, it is widely demanded in construction sectors. It possesses a good weldability too in both arc and gas welding conditions. In the present work four pairs of AISI 1020-0.2%C steel plates were welded by shielded arc welding method. Except one welded plate, other three were heat treated. Based on the heat treating, three different physical conditions were achieved- water quenched, oil quenched and annealed. All the samples were tested for tensile strength, hardness, and microstructure. The annealed specimen has showed a significantly improved tensile strength of 439 MPa which is 85% higher than as-welded specimen. Water and oil quenched specimens showed lesser strength than that of as-welded specimen. With regard to hardness, there were two different observations. The as-welded and annealed specimens indicated the highest hardness at welded joint whereas the lower values were reported in base metal part. In contrary, the water and oil quenched specimens were harder in base metal zone as compared to welded zone. Both, strength, and hardness were found in good correlation with microstructural appearance of the plates.