Grain growth behavior of blade steel KT5331 for ultra-super critical units
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摘要: 通過在不同溫度下等溫奧氏體化,研究KT5331鋼奧氏體晶粒長大行為,并探討析出相對奧氏體晶粒長大行為的影響機理.研究表明,KT5331鋼奧氏體晶粒長大可分為三個階段:1075℃以下,由于含W和Nb的析出相釘扎作用,晶粒長大緩慢;1075℃以上,含W和Nb的析出相溶解,釘扎作用減弱,隨加熱溫度和保溫時間延長晶粒迅速長大;1225℃及以上,δ鐵素體析出,晶粒尺寸隨加熱溫度升高而急劇減小.通過擬合分別得到晶粒粗化溫度以下(950~1075℃)和晶粒粗化溫度以上(1100~1200℃)的晶粒長大模型.Abstract: The austenite grain growth behavior of KT5331 steel and the effect of precipitates on the austenite grain growth were studied by isothermal austenization at 950-1280℃. The results show that the austenite grain growth process can be divided into three stages. Due to the pinning effect of precipitates containing W and Nb,the austenite grains grow slowly below 1075℃. Most of the precipitates dissolve above 1075℃,leading to the austenite grains coarsened. When the temperature rises to 1225℃,δ-ferrite precipitates and results in austenite grain refinement with increasing temperature. The austenite grain growth models below and above the coarsening temperature 1075℃ were established by numerical fitting.
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Key words:
- heat resistant steel /
- austenite /
- grain growth /
- mathematical models
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