Abstract

Laser beam offset welding of GH3128 and molybdenum (Mo) dissimilar joints was studied with an emphasis on the role of laser beam offset (LBO). It was found that the change of LBO significantly affected the properties of GH3128/Mo dissimilar joints. When the LBO increased from − 0.1 mm (i.e., laser spot was centered on Mo surface) to + 0.3 mm (i.e., laser spot was centered on GH3128 surface) at the step size of 0.1 mm, the amount of melted Mo gradually declined; the welding mode gradually changed from fusion welding to welding–brazing; macro-segregation of Mo-rich phases in fusion zone (FZ) gradually disappeared; the average microhardness of FZ significantly decreased, and therefore, microhardness distribution in FZ became more uniformly; the quantity of grain boundary liquation observed in heat-affected zone (HAZ) of GH3128 side gradually decreased; and recrystallization of grains in the HAZ of Mo was gradually suppressed. Joints with the optimal LBO of + 0.2 mm reached the maximum tensile strength of about 560 MPa. When using a small LBO, i.e., LBOs were + 0.1, 0, − 0.1 mm, the HAZ of Mo was greatly softened and embrittled. When adopting a large LBO, i.e., LBO was + 0.3 mm, the melt near Mo-FZ interface might fail to moisten Mo surface and spread on Mo surface, thus resulting in the reduction in tensile strength.

中文翻译：

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激光焊接GH3128 / Mo异种接头的组织和性能

摘要

研究了GH3128和钼（Mo）异种接头的激光束偏移焊接，重点是激光束偏移（LBO）的作用。发现LBO的变化显着影响GH3128 / Mo异种接头的性能。当LBO以0.1mm的步长从-0.1mm（即，激光点在Mo表面上居中）增加到+ 0.3mm（即，激光点在GH3128表面上居中）时，Mo的熔化量逐渐减少；焊接方式逐渐从熔焊转变为钎焊。熔融区（FZ）富钼相的宏观偏析逐渐消失。FZ的平均显微硬度明显降低，因此FZ的显微硬度分布变得更加均匀。在GH3128侧热影响区（HAZ）观察到的晶界液化量逐渐减少；Mo的热影响区中的晶粒再结晶逐渐被抑制。最佳LBO为+ 0.2 mm的接头达到了约560 MPa的最大抗拉强度。当使用小的LBO时，即LBO为+ 0.1、0，-0.1 mm，Mo的热影响区会大大软化和脆化。当采用大的LBO时，即LBO为+ 0.3mm，Mo-FZ界面附近的熔体可能无法润湿Mo表面并在Mo表面上扩散，从而导致拉伸强度降低。钼的热影响区被大大软化和脆化。当采用大的LBO时，即LBO为+ 0.3mm，Mo-FZ界面附近的熔体可能无法润湿Mo表面并在Mo表面上扩散，从而导致拉伸强度降低。钼的热影响区被大大软化和脆化。当采用大的LBO时，即LBO为+ 0.3mm，Mo-FZ界面附近的熔体可能无法润湿Mo表面并在Mo表面上扩散，从而导致拉伸强度降低。