冷却速度对CAP1400核主泵泵壳用奥氏体不锈钢铸造组织的影响

Effect of Cooling Rates on Cast Microstructure of Austenitic Stainless Steel for CAP1400 Nuclear Pump Casing

采用OM、SEM和EPMA手段分析了CAP1400泵壳用奥氏体不锈钢在1480℃重熔后以不同速度冷却至1340℃后水冷的凝固组织,研究了不同冷却速度对铁素体相分数及成分的影响规律。结果表明,CAP1400泵壳用奥氏体不锈钢重熔后的凝固组织主要由奥氏体相和残余δ铁素体相组成。凝固速度越快,残余δ铁素体相含量越多,奥氏体含量越少,且粗大的奥氏体相变得更为细小。在同一凝固速度下,δ铁素相中Cr、Si、Mo、Mn元素含量均高于奥氏体相。随着凝固速度的加快,δ铁素体相和奥氏体相中的Cr含量升高,而Ni、Si、Mo、Mn含量的波动幅度较小。

The solidification microstructure of austenitic stainless steel for CAP1400 pump shell after re-melting at 1480℃and cooling with different speeds to 1340℃was analyzed by using optical microscope(OM),scanning electronic microscope(SEM)and electronic probe micro-analyzer(EPMA).The effect of different cooling rates on the phase fraction and composition of ferrite was studied.The results show that the solidification microstructure of austenitic stainless steel for CAP1400 pump shell after re-melting is mainly composed of austenite phase and residualδferrite phase.The faster the solidification rate is,the more the content of residualδferrite phase is,the less the austenite content is,and the smaller the coarse austenite phase is.At the same solidification rate,the content of Cr,Si,Mo,Mn inδferrite phase is higher than that in austenite phase.With the increase of solidification rate,the Cr content inδferrite phase and austenite phase increases,but the fluctuation range of Ni,Si,Mo,Mn content is small.