低溫沃斯成形對Fe-0.6C-2Si-xMn (x=1, 2, wt%)合金鋼奈米變韌鐵微結構發展之影響

Effects of low-temperature asuforming on the miscrostructural evolution in Fe-0.6C-2Si-xMn (x=1, 2, wt%) nanobainitic steels

童博彥(Po-Yen Tung)

指導教授 ： 楊哲人

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.01069

摘要

奈米變韌鐵具有很高的潛力作為防彈材料，也因此被廣泛地研究許多年。雖然奈米變韌鐵同時具有高強度以及高伸長率，但是由於其中的塊狀沃斯田鐵的不穩定，使其為此材料嚴重的缺點。因此，在我們的研究中，主要的目的是改善材料中塊狀沃斯田鐵的性能。首先，我們引進沃斯成行製程—在等溫變韌鐵相變態之前，對材料進行低溫塑性變形—來改變傳統奈米變韌鐵的微結構。第二，我們更進一步利用EBSD技術來測量沃斯成形後塊狀沃斯田鐵的穩定性。除此之外，我們也同樣利用EBSD技術來分析殘留塊狀沃斯田鐵和變韌鐵之間的方位關係。在有沃斯成形的變韌鐵中，塊狀沃斯田鐵以及變韌鐵會同時被細化而變得均勻分布。藉由沃斯成形，被細化的塊狀沃斯田鐵也被更進一步地機械穩定。也因為沃斯成形的緣故，Shockley部分差排在滑移面上的滑動也促進了變體選擇，並利用EBSD技術測量之。

關鍵字

低溫沃斯成形 ； 沃斯田鐵之機械穩定 ； 奈米變韌鐵結構 ； 殘留塊狀沃斯田鐵 ； 極圖 ； 沃斯田鐵之熱穩定性

並列摘要

Nanostructured bainite, having high potential as the bulletproofing material, has been studied for many years. Nanostructured bainite possesses high strength, high elongation, but its low toughness due to the instability of blocky austenite is a serious disadvantage. So, the primary propose in this work is to improve the properties of blocky austenite. First, we introduce ausforming process—plastic deformation at low temperature before isothermal bainitic transformaiton—to change the microstructure of traditional nanostructured bainite. Second, we further measure the stability of blocky austenite in ausformed bainite by EBSD. Besides, the orientation relationship between blocky austenite and bainitic ferrite is analyzed by EBSD. In ausformed bainite, the blocky austenite and bainitic sheaves are simultaneously refined and well-distributed. The refined blocky austenite is further mechanical stabilized by ausforming process, which might benefit to mechanical properties. Due to ausforming process, variant selection is assisted by Shockley partial dislocations and measured by EBSD.

並列關鍵字

low-temperature ausforming ； mechanical stabilization of austenite ； nanobainite structure ； retained blocky austenite ； pole-figure ； thermal stability of austenite

參考文獻

[4] Z. Nishiyama, Sci. Rep. Tohoku Nuiv, 64 (1934) 325.

[6] H.K.D.H. Bhadeshia, Bainite in steels : transformations, microstructure and properties, IOM Communications, London, 2001.

[7] E. Swallow, H. Bhadeshia, Mater. Sci. Technol., 12 (1996) 121-125.

[8] L.C. Chang, H. Bhadeshia, Mater. Sci. Technol., 12 (1996) 233-236.

[10] H. Bhadeshia, Acta Metallurgica, 29 (1981) 1117-1130.