Effect on microstructure of TMT welded bar under different cooling media

摘要

Arc welding is widely used for domestic as well as industrial purposes as it is very convenient to use. Mechanical properties such as tensile strength and hardness depend on microstructure. This paper presents the results of metallography examination of weld zone and heat affected zone (HAZ) in the welded rod which are welded and cooled in air, transformer oil, kerosene oil and water. The rate of cooling differs from each media thus there is microstructure change in weld zone as well as HAZ. In the weld zone, hardness is found to be more in case of transformer oil cooled sample in comparison with others cooling method applied here. The toughness of water cooled sample is found to, be more because of its presence of large amount offerrite region along with pearlite and martensite. In the heat affected zone, water cooled sample is found to possess mare hardness due to formation of martensite. The arc welded transformer oil cooled sample seems to be best among all with regard to its structure, hardness and toughness.