6wt.%Si高硅奧氏體不銹鋼固溶處理過程中BCC相的演變機制研究6wt.%Si高硅奧氏體不銹鋼固溶處理過程中BCC相的演變機制研究Study on evolution mechanism of BCC-phase during solution treatment in 6wt.% Si high silicon austenitic stainless steel 利用OM，SEM，XRD和TEM等方法對6wt.%Si鑄態高硅奧氏體不銹鋼在不同固溶處理溫度下的BCC相的演變規律進行了研究，分析了不同固溶處理溫度下組織中BCC相的回溶與重新析出過程中元素變化、形貌和結構特征，并制定合理的熱處理制度。結果表明， 6wt.%Si高硅不銹鋼鑄態組織中的析出相主要為BCC相，該相沿晶界和枝晶間分布，并富含Mo、Si、Ni等元素，晶格常數a=8.747?。樣品在1050℃-1200℃×2h固溶處理時，BCC析出相中的Mo、Cr元素含量隨溫度的升高而增加；當溫度達到1200℃時BCC相發生回溶，在1250℃×2h固溶處理時BCC相重析出。 The BCC-phase evolution mechanism of 6wt.% Si as-cast high-silicon austenitic stainless steel under different solid solution treatment temperature was investigated by means of OM，SEM，XRD and TEM. In order to study the precipitation and re-dissolution of BCC-phase, the distribution of alloy elements, morphology and crystal structure of the BCC-phase were analyzed under different solution treatments. Moreover, the heat-treated schedules were made based on the experimental results. The results indicated that the solid solution treatment temperatures had a great influence on the microstructure of 6wt.% Si high-silicon austenitic stainless steel. The precipitates existed in the as-cast structure were mainly BCC-phase with a lattice constant of 8.747?, rich in Mo, Si and Ni elements, and distributed in grain interior and grain boundary. The BCC-phase redissolved during the solution when the temperature was between 1050℃-1200℃ for 2h. The contents of Mo, Si and Ni increased with the rising solution temperature. Furthermore, the BCC-phase re-precipitated when the test specimen was heat treated at 1250℃ for 2h.The re-precipitated phase has the same composition with that in the as-cast structure. Thus the optimal solid solution treatment temperature of 6wt.% Si high-silicon austenitic stainless is 1100℃-1200℃ for 2h.
|
