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采用RDL100型电子高温蠕变试验机、OM、SEM、TEM分析测试了新型Cr19Ni28TiN铁镍基合金的蠕变性能。蠕变试验结果表明,当加载应力减少到250 MPa时,出现明显稳态蠕变阶段;微观组织观察显示蠕变前奥氏体基体上均匀分布着少量的析出相,在600℃、300 MPa下蠕变后晶界和晶内都弥散析出大量的细小的TiN和M23C6;晶内析出相对位错产生钉扎作用,阻碍位错的移动,同时大量位错在共格晶界附近塞积,形成位错墙,提高了合金的蠕变强度。600℃、300 MPa条件下蠕变断裂分析表明,Cr19Ni28TiN合金断口平齐,存在一些较浅的撕裂韧窝,凹坑中的第二相成为裂纹的核心。
The creep property of the new Cr19Ni28TiN iron-nickel based alloy was tested by RDL100 electronic high temperature creep tester, OM, SEM and TEM. The creep test results show that when the loading stress is reduced to 250 MPa, a clear steady-state creep stage appears. Microstructure observation shows that a small amount of precipitates are uniformly distributed on the austenite matrix before creep. Under 600 MPa and 300 MPa A large amount of small TiN and M23C6 are precipitated in the grain boundaries and in the grain after creeping. The relative dislocations in the grain are pinned and impede the movement of the dislocations. At the same time, a large number of dislocations are plugged near the coherent grain boundaries to form Dislocation walls improve the creep strength of the alloy. The analysis of creep rupture at 600 ℃ and 300 MPa shows that the fractures of Cr19Ni28TiN alloy are flush with shallow tearing dimples, and the second phase in the crater becomes the core of the crack.