This study is an experiment to prove that some welding is efficient and weldability is excellent, when parts of the frequent maintenance and replacement due to wear-resistant or vibrations repeated in field environments are welded with dissimilar materials.
The test materials are general rolling structural steels SS400 which is the most widely used in the field and stainless steel STS304.
Welding methods were CO₂ welding and MIG welding and they were performed by automatic welding device.
In this study, the experiment was conducted by the good selection of specimens through radiographic testing then hardness tests, tensile tests, fatigue tests, fatigue propagation tests were conducted, also metal tissue was observed.
Hardness test results, the dissimilar metal welding C series showed a good result when compared to the dissimilar metal welding B series.
The results of tensile test are A series test piece 551.2MPa, strain 33.45%, B series test piece 463MPa, strain 39.88%, C series test piece 623.4MPa, strain 48.42%, D series test piece 636.2MPa, strain 47.82% These results suggest that strength is good and welding is suitable.
Based on fatigue limit cycle, Because compared with fracture cycle, as weld defects range plentifully from HAZ to welding zone boundary, the crack destroyed by repeated load broke out and developed in HAZ than in welding zone. The results of fatigue tests, C series showed the best value when compared with the other specimens.
Fatigue crack propagation test results, HAZ(m=2.7054) in the C series welded MIG was destroyed by the slow progress, HAZ(m=3.3324) in the B series welded CO₂was destroyed by the rapid progress. These results are expected that together with the material properties, MIG welding is done because of high current density by high-current.
As a result, arising in each fracture surface, early-age cracking can gradually be seen to develop, striations are seen while its growth process, and dimple is detected in its each part in last fracture zone.
Taken together the results of the experiment, C series in the various tests has shown the best result. If welding condition is controlled and dissimilar metal welds with MIG welding, it can be an excellent welding with durability ablation and vibration.