Abstract:
This study aims to determine the effect of preheating and current strength on the results of microstructure and tensile test values of SMAW welding results on ST 42 steel. This research was carried out experimentally in the laboratory. The research process starts from making specimens, welding process with currents of 80A, 90A and 100A with variations of preheating at room temperature (32°C), 200°C and 400°C, then microstructure and tensile tests are carried out. Manufacture of specimens according to ASTM E8 standards with a length of 200 mm, a width of 20 mm, a plate thickness of 4.7 mm. microstructure test found the content of Ferrite, Austenite, Ledebrite, Martensite and Bainite. And the tensile test value got the highest value at 90A with preheating 400°C with a value of 442 MPa also the lowest value was at 90A with no preheating (32°C) with a value of 320 MPa. The results showed that 90A current was the most efficient compared to 80A and 100A current, which showed a continuous increase in each addition of the preheating process compared to 100A current strength which decreased its tensile test value with each additional preheating process.
