激光修复GH4169高温合金的持久断裂机制研究  

Research on Persistent Fracture Mechanism of Laser Forming Repaired GH4169 Superalloy

作　　者：明宪良 陈静[1] 谭华[1] 杨海欧[1] 林鑫[1] 

机构地区：[1]西北工业大学凝固技术国家重点实验室,陕西西安710072

出　　处：《中国激光》2015年第4期63-69,共7页Chinese Journal of Lasers

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)

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。The microstructure and persistent properties of the wrought samples and the laser forming repaired （LFR） samples of GH4149 alloy are investigated.The results show that the microstructure of wrought substrate is characteristic of equiaxed grains, and there are grainess and short rod like 8 phase distributes in and along boundaries of the grains, which can effectively prevent dislocation motion and reduce the rate of crack propagation. Compared with as-deposited samples, the microstructure of laser repaired GH4169 alloy with double aged （DA） treatment changes little and still is characteristic of columnardendrites which grow epitaxially along the deposition direction of the substrate. There are still masses of Laves phase precipitations between dendrites. Laves phase is a brittle phase which provides a favorable position for the initialization and expansion of the cracks. The fracture mechanism of wrought sample suffering from high temperature is due to microvoid coalescence fracture, and the MC ~ 8 phase are nucleation centers of micropores which form dimples with different shapes and sizes after fracture. The break of the repaired samples suffering from high temperature lood occurs in the repaired zone. The interdendritic Laves phase ~ MC are nucleation centers of the dimples, thus leaving the dimples of recognizing interdendritic region as dimple center and dendrite dry region as torn edges.

关 键 词：激光技术 激光修复 GH4169高温合金 显微组织 持久性能 断裂机制 

分 类 号：TG146.4[一般工业技术—材料科学与工程] TN249[金属学及工艺—金属材料]