Abstract
The laser welding of which is next-generation joining technology is expected in automobile industry for alternative technology to the spot welding. However, it is not applied widely because there are few studies about fatigue properties of its welding joint. In this study, in order to acquire the knowledge about the fatigue properties and fracture mechanism of the laser welded joints of thin steel sheets, fatigue tests were conducted using the laser welded joints which have general automotive steel as base metal under the tensile loading condition. The test results showed that the fatigue life of the laser welded joints was slightly shorter than that of the spot welded joints. Then, the interior fatigue crack propagation around the welded area was observed in detail. As a result of three-demensional observations of each welded joints, it is found that the difference of the fatigue life is caused by the difference of the crack initiation life. Although there are some differences, they are very slightly. Therefore, there is a possibility to apply the laser welding to automobile as the alternative technology to the spot welding.
