Paper Title
EFFECT OF HEAT TREATMENT ON THE IMPACT STRENGTH OF SA-36 STEEL

Abstract
This study was carried out to measure the impact strength of SA-36 steel specimens before and after heat treatment. Hot rolling is the as-built condition, followed by two post-treatments: annealing and quenching. Annealing was carried out at 690℃ for 30 minutes followed by a slow cooling in the furnace. After being heated to three distinct temperatures (1010°C, 1515°C and 1020°C), specimens are cooled in air and oil, for quenching. The impact strength was determined using Charpy impact testing in accordance with the ASTM-E23 standard. Tests were performed on both as-built and heat-treated specimens. The average of three readings is used to calculate the modulus of impact strength for each condition. The as-built specimens had impact strength values of 1134 kJ/m2. Oil quenched specimens demonstrated an overall increasing trend, with values of 1236 kJ/m2, 1165 kJ/m2, and 1150 kJ/m2 at 1010°C, 1515°C, and 1020°C, respectively. The air quenched specimens similarly showed an increasing tendency, but the values recorded were higher than the oil quenched ones. The values calculated were 1435 kJ/m2, 1376 kJ/m2, and 1165 kJ/m2 at 1010°C, 1515°C, and 1020°C, respectively. The higher impact strength value in air-cooled specimens is due to slow cooling, which causes the transformation into soft, coarse, and less dislocated phases. It is evident that 1010°C with air cooling yields the highest impact strength and provided the optimal condition. Keywords - SA-36 steel, Impact Strength, ASTM-E23, Heat treatment, Charpy test