- 期刊
不鏽鋼連鑄之凝殼成長與δ-ferrite含量及分佈研究
Shell Growth and δ-Ferrite Content and Its Distribution in Austenitic Stainless Steel Slabs
摘要
本文探討奧斯田鐵系不鏽鋼扁胚，在連鑄過程中之凝固現象及相變化。藉由爆湯殼的厚度測量，討論及比較不鏽鋼及碳鋼二者在凝殼成長行為的差異。從幾種不同澆鑄條件下之扁鋼胚所測得的δ-ferrite（肥粒鐵）含量得知，除了窄面以外，沿厚度方向的δ-ferrite分量分佈皆呈”M”形，且離窄面愈遠愈明顯。利用電腦，以建立在數值運算的熱傳分析著手，估計δ→γ相變化的擴散時間，以瞭解冷卻速率對δ-ferrite含量影響。本研究得知化學成份主要影響鋼液的凝固模式及δ-ferrite含量，而冷卻速率則會影響δ-ferrite分佈。就裂敏感性SUS316L而言，煉鋼需精確控制鋼液化學成份，使具有合適Creq/Nieq並減少P、S等元素，而連鑄應採用緩冷卻設計。
並列摘要
The solidification process and shell growth of austenitic stainless steel during continuous casting has been studied. The thickness of breakout shell measured and the shell growth in stainless steel was compared with that in carbon steel. The δ. ferrite content of slabs was measured for various casting conditions. Except in the narrow face, the ferrite distribution in the slab has been observed to be in ＂M-like＂ shape. Computer analysis was carried out to evaluate the diffusion time available for δ→γ transformation. Steel composition has been observed to be primary controling the solidification mode and δ-ferrite content, while cooling rate affects the o ferrite distribution. Therefore, steel chemistry control, including Cr_(eq)/Ni_(eq) and P,S elements in steelmaking, is essential for crack-sensitive stainless steels.