Z3CN20.09M铸造双相钢热老化的调幅分解

Spinodal Decomposition in the Thermal Aging Process of Z3CN20.09M Cast Duplex Stainless Steel

基于核电站压水堆的一回路主冷却管道的服役条件,本文对Z3CN20.09M铸造双相不锈钢进行了长时热老化实验,采用透射电镜对其老化态的显微组织进行观察,从热力学和动力学方面分析其随热老化时间的转变规律.实验结果表明,铁素体相在热老化3 000h后开始发生调幅分解,形成了明暗相间富铁的α相和α′相斑点状组织,在α/γ相界有极少量Cr2N相析出.调幅分解首先在晶界发生,随着老化时间延长,逐渐向晶内扩展.老化12 000h后调幅分解进行较充分,而且铁素体基体和位错线上有与之共格的G相析出.整个老化分解过程符合经典调幅分解理论.

The microstructure of Z3CN20 .09M cast stainless steel's different aging state was observed by transmission electron microscopy under its service condition .T he thermal aging transformation rule was analyzed by thermodynamic .The results showed that spinodal decomposition started to occur in the ferrite phase after the aging 3000 hours ,and formed the light and dark Fe-richα-phase ,Cr-richα'relative punctate tissue and a very small amount of Cr2 N phase precipitates in the α/γphase boundary .In ferrite phase ,spinodal decomposition firstly occurred at the grain boundaries ,then extended to the intragranular later ,finally became more fully after 12 ,000 hours and there was coherent G-phase precipitation at the ferrite matrix and the dislocation line .The entire aging decomposition process was in line with the classical theory of spinodal decomposition .