C-HRA-3耐热合金850℃持久性能及组织特征

Stress rupture properties and microstructure characteristic of C-HRA-3 heat-resistant alloy at 850 ℃

研究了C-HRA-3耐热合金在850℃持久试验过程的碳化物特征。结果表明:当持久应力为120 MPa时,持久寿命为37. 8 h,主要析出相包括M23C6相和Ti(C,N)相,高应力状态下,M23C6相沿变形带析出。当持久应力为80 MPa时,持久寿命延长至491 h,晶界处M23C6相部分回溶,导致晶界特征不明显,同时细小M23C6相重新析出,晶内析出的Ti(C,N)相尺寸增加。不同应力下试样的断裂方式均为沿晶断裂,裂纹源优先在尺寸较大的析出相(M23C6和Ti(C,N))周围萌生,导致伸长率随持久寿命延长而减小。

The carbide characteristics of C-HRA-3 heat-resistant alloy during the creep rupture test at 850 ℃ were studied. The results show that when the stress is 120 MPa,the rupture time is 37. 8 h. The main precipitated phases are M23C6 and Ti( C,N) phase. Under high stress condition,M23C6 phase precipitates along the deformation zone. When the stress is 80 MPa,the rupture time is prolonged to 491 h,the Ti( C,N) in inter-granular grows and coarsens,and the M23C6 phase at the grain boundary partially dissolves,resulting in the indistinct grain boundary characteristics and the re-precipitation of the fine M23C6 phase. The fracture modes of specimens under different stress condition are inter-granular fracture,and the crack source preferentially sprouts around the larger precipitates(M23C6 and Ti( C,N)),resulting in the decrease of the elongation of the rupture section with the extension of the rupture time.