While conducting U-type hot-cracking tests on gas tungsten arc welding (GTAW) specimens, we irradiate the specimens with a laser beam (multi-beam welding) to prevent solidification cracking. To account for the observed suppression of solidification cracking, we calculate the thermal strain and high-temperature ductility curve using finite-element simulation and metallurgical analysis models, respectively. The high-temperature ductility curves do not exhibit any variation between the welding conditions because the temperature history of the molten pool is unchanged for all three welding scenarios considered. The GTAW thermal strain curve intersects with the high-temperature ductility curve, corresponding to the occurrence of cracking. However, in multi-beam welding, cracking is suppressed because of the relative decrease in thermal strain. The area of laser-beam irradiation is larger because of the resulting decrease in yield strength. As a result, in multi-beam welding, the reduced specimen expansion leads to reduced stress loading on the weld bead, thereby preventing cracking because of the thermal strain decrease.

在对钨极氩弧焊（GTAW）试样进行U型热裂纹测试时，我们用激光束照射试样（多束焊接）以防止凝固裂纹。为了解决观察到的对凝固裂纹的抑制作用，我们分别使用有限元模拟和冶金分析模型计算了热应变和高温延性曲线。高温延展性曲线在焊接条件之间没有任何变化，因为考虑到的所有三种焊接方案，熔池的温度历史都没有改变。GTAW热应变曲线与高温延性曲线相交，对应于裂纹的发生。但是，在多束焊接中，由于热应变的相对降低而抑制了裂纹。由于屈服强度的降低，激光束照射的面积较大。结果，在多束焊接中，减小的试样膨胀导致减小了施加在焊道上的应力，从而防止了由于热应变的降低而导致的裂纹。