Effect of Cooling Media on the Hardness and Microstructure of AISI 1020 Steel in the SMAW Welding Process

Abstract

This study aims to determine the effect of cooling media on the hardness and microstructure of AISI 1020 steel during SMAW welding. In the SMAW welding process, variations in cooling media, such as coolant, air, and oil, are used to affect the mechanical properties of the weld. After the welding process, hardness testing is performed on the weld area and HAZ using Vickers testing, and microstructure observation is carried out using a scanning electron microscope to analyze the changes that occur. The SEM test results show that in the welding of SMAW AISI 1020 steel, the weld area and HAZ are more dominant in the ferrite phase than in the pearlite phase. Steel with low carbon will contain more ferrite than pearlite, and slow cooling after heating can also increase the ferrite content. This can be seen in the hardness value in the HAZ area with oil cooling medium, which has the highest hardness value compared to air cooling and coolant. The results of the hardness test in the LAS area showed the largest average hardness value in the coolant-cooling variation at 134.4 N/mm², while the smallest average hardness value was found in the free-air cooling at 102.6 N/mm². In the HAZ area, the largest average hardness value is found in the oil-cooler variation at 183.6 N/mm², and the smallest average hardness value is found in free-air cooling at 99.8 N/mm².