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采用RDL100型电子高温蠕变试验机测试了新型Cr18Ni9Nb Ti N奥氏体不锈钢在650℃不同应力下的蠕变性能。利用SEM、TEM及EDS等观察分析了220 MPa下不同蠕变阶段的组织形貌。结果表明,蠕变初期,晶内位错密度急剧增加,位错发生缠结,晶内有细小的Nb N相弥散析出;稳态蠕变阶段,位错形成网状结构,晶内有Ti N颗粒析出,链状(Cr,Fe)23C6沿晶界析出,位错网和析出的第二相共同降低了位错可动性,改善了合金抗蠕变性能;加速蠕变阶段,大量扩展位错出现,延长了蠕变寿命。Cr18Ni9Nb Ti N钢蠕变断裂属于沿晶脆性断裂,晶界处发现部分(Cr,Fe)23C6剥落,三叉晶界处发现楔形裂纹。
The creep behavior of the new Cr18Ni9Nb TiN austenitic stainless steel under different stresses at 650 ℃ was tested by RDL100 electronic high temperature creep tester. The morphology of the samples at different creep stages at 220 MPa was analyzed by SEM, TEM and EDS. The results show that in the early stage of creep, the density of dislocations increases sharply, the dislocations are entangled, and fine Nb N phase is precipitated in the grain. In the steady state creep stage, dislocations form a network structure with TiN Particles precipitate, the chain (Cr, Fe) 23C6 precipitation along the grain boundaries, the dislocation network and precipitation of the second phase together reduce the dislocation mobility and improve the creep resistance of the alloy; accelerated creep stage, a large number of expansion Wrong appearance, extending creep life. The creep rupture of Cr18Ni9Nb TiN belongs to brittle fracture along grain boundaries, and some (Cr, Fe) 23C6 flakes are found in the grain boundaries, and wedge-shaped cracks are found in the trigeminal grain boundaries.