GH3536/DD6异质合金激光搭接焊对母材组织和性能的影响

Effect of laser lap welding of GH3536/DD6 heterogeneous alloy on microstructure and properties of base metal

【目的】单晶空心涡轮叶片铸造成形时需要预先在叶片底部留出工艺孔,以便后续陶瓷型芯经化学腐蚀后从叶片中流出。脱芯完成后,为保证空心叶片的使用性能,需要使用节流片密封工艺孔。针对于此,进行航空发动机叶片原材料DD6单晶合金和GH3536变形高温合金异种材料激光焊接的研究,期望通过激光焊接的方式实现DD6和GH3536异种材料的连接,进而解决密封问题。【方法】该文研究了DD6和GH3536的可焊性,观察DD6/GH3536激光焊接接头的显微组织、元素过渡情况,分别测试了经过激光焊接的DD6和未经过激光焊接的DD6的力学性能。【结果】结果表明,DD6母材侧焊缝底部主要为细密的柱状晶,顶部为等轴晶;激光焊接后DD6一侧出现与其晶粒取向不同的重熔结晶区,靠近重熔结晶区的γ'相出现熔解。高温拉伸、高温持久试验结果表明,接头的抗拉强度、屈服强度与DD6母材相当,持久性能略高于DD6母材,断裂均发生在DD6激光焊接部位。【结论】通过激光焊接,可以实现DD6与GH3536的连接,连接处冶金情况良好。

[Objective]In the casting process of single crystal hollow turbine blades,process holes should be left in the bottom of blades in advance,so that ceramic core could flow out of blades after chemical corrosion.After core removal was completed,in order to ensure performance of hollow blades,it was necessary to use throttle to seal process holes.In view of this,laser welding of aero engine blade raw material DD6 monocrystalline alloy and GH3536 deformed superalloy dissimilar material was studied,and connection of DD6 and GH3536 dissimilar material was expected to be realized by laser welding,so as to solve the sealing problem.[Methods]In this paper,weldability of DD6 and GH3536 was studied,microstructure and elemental transition of DD6/GH3536 laser welded joints were observed,and mechanical properties of laser welded DD6 and non-laser welded DD6 were tested respectively.[Results]The results showed that the bottom of weld on the side of DD6 base metal was mainly fine columnar grains,and the top was equiaxed grains.After laser welding,a remelting crystallization zone with different grain orientation appeared on the side of DD6,andγ'phase near the remelting crystallization zone was melted.The results of high temperature tensile and high temperature endurance test showed that tensile strength and yield strength of welded joints were similar to those of DD6 base metal,and durability of welded joints was slightly higher than that of DD6 base metal.All the fractures occurred at the laser welding site of DD6.[Conclusion]Through laser welding,DD6 and GH3536 could be connected,and the connection was in good metallurgical condition.