용접 모니터링을 활용한 SS400강의 GMAW 혼합가스 조성에 따른 용접부의 기계적 특성에 관한 연구

A Study on Mechanical Feature of the Welding Part according to GMAW Compound Gas of SS400 Steel using Welding Monitoring

Rolled steel(SS400, 9mm) and welding rod of 1.2mm solid wire were used to fix current, voltage and gas flux via GMAW welding, pre-welding test with the optimal conditions were used for welding monitoring and the rate of gas compound (CO2 100%, CO2 25%+Ar75%, CO2 50%+Ar50%, CO2 75%+Ar25) was changed for auto welding. Each test measured sealing intensity, stretching rate, hardness and shocking degree, while optic microscope observed change of metal structure to see the influence of gas compound change on the mechanical feature; which resulted in the following. 1. Sealing intensity of weld metal zone was the highest at CO2 50%+Ar50% and the lowest at CO2 75%+ Ar25%, while stretching rate was in inverse proportion to the sealing intensity. 2. Sharpy impact value was the highest at 0℃ and Ar 50%, which was the same as sealing intensity and hardness. 3. Hardness of weld metal zone was the highest when Ar50% was mixed, which was higher in case of CO2 100%. 4. As a result of observing structure, it showed general welding part of ferrite and bainite; and ferrite structure slightly increased while bainite decreased, as Ar gas increased.