激光修复GH4169高温合金的持久断裂机制研究

发布时间：2018-09-09 14:23

【摘要】：对GH4169合金锻件与激光成形修复(LFR)件进行显微组织观察和持久性能实验。结果表明:锻造GH4169合金组织为等轴晶,在晶界和晶内弥散析出颗粒状或短棒状δ相,可有效阻碍位错运动以及降低裂纹扩展速率;激光修复GH4169合金经直接双级时效处理(DA)后,与沉积态相比,组织特征变化不大,呈现为沿沉积方向外延生长的柱状枝晶,枝晶间仍然存在块状Laves相,Laves相作为一个脆性相,为裂纹的起源和扩展提供了有利的位置和通道。锻件试样经受高温持久载荷时的断裂机制表现为微孔聚集型断裂,其中δ相、碳化物(MC)是微孔形成的核心,并且断裂后留下了形状与尺寸各异的韧窝组织。激光修复试样经受高温持久载荷时断裂发生在修复区一侧,韧窝以枝晶间Laves相和MC为形核中心,因此留下了以枝晶间区域为韧窝中心和以枝晶干区域为撕裂棱的韧窝组织。
[Abstract]:The microstructure and rupture properties of GH4169 alloy forgings and (LFR) repaired by laser forming were observed. The results show that the microstructure of forged GH4169 alloy is equiaxed, and granular or short rod 未 phase is precipitated in grain boundary and crystal, which can effectively block dislocation movement and decrease crack propagation rate, and laser repair GH4169 alloy after direct two-stage aging treatment of (DA). Compared with the deposited state, the microstructures have little change, showing columnar dendrites growing along the deposition direction, and there is still a block Laves phase as a brittle phase between the dendrites, which provides a favorable position and channel for the origin and propagation of the cracks. The fracture mechanism of forgings subjected to high temperature lasting load is micropore aggregation fracture, in which 未 phase, carbides (MC) are the core of micropore formation, and dimples of different shapes and sizes are left after fracture. The fracture occurred at one side of the repair zone and the dimples were nucleated by interdendritic Laves phase and MC. Therefore, the dimples with the dendrite region as the dimple center and the dendritic dry region as the tearing edge were left.
【作者单位】：西北工业大学凝固技术国家重点实验室;
【基金】：国家自然科学基金(51105311) 西北工业大学基础研究基金(NPU-FFR-JC201234)
【分类号】：TG665;TG132.3

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