臺灣博碩士論文加值系統

錳(Mn)元素為一種可增加並微細化鑄鐵組織中波來鐵以提高強度之元素
，然而添加過高的錳含 量(> 0.7%)卻容易促使晶胞間碳化物形成致造成
鑄件材質之脆化[40]。本研究乃針對添加不同 錳含量(分別
是0.31%,0.35%,0.56%,0.97%四種)，藉由鑄態下所獲得之機械性質再施以
完全退 火熱處理與次臨界退火熱處理，藉以探討鑄態下與熱處理後對不
同厚斷面機械性質之影響。經 實驗所得之結果顯示，錳含量添加愈多於
鑄態下確可獲得較高之抗拉強度與硬度，但相對地使 延性、衝擊韌性降
低，而隨著斷面厚度愈增加時，抗拉強度與硬度有下降之趨勢，但延性與
韌 性受斷面厚度之影響則較不規律。至於熱處理後之機械性質，以相同
錳含量而言，肥粒鐵化退 火熱處理後之抗拉強度與延性有比完全退火熱
處理後之性質優，但硬度較差。而隨著斷面厚度 愈增加時，兩種熱處理
方式之抗拉強度均有逐漸往下降而延性往上升之趨勢，然衝擊韌性與硬
度則較不規律。本文亦試圖由微觀組織來解釋上列之機械性質行為。

Mn element can increase and refine pearlite thus enhances
strength in cast iron. However, matrix of cast iron
would become embrittled when intercellular carbides formed due
to excess amount of Mn (>0.7%)[40]. In this study, the
effects of different Mn amount (0.31%, 0.35%, 0.56%,
0.97%) on mechanical properties of ductile iron of various
thickness in as-cast state and after full annealing / sub-
critical annealing were investigated. The results indicated
that the strength and hardness increased with amount of Mn,
but the ductility and impact values decreased. Strength
and hardness decreased with increasing section thickness, but
the effects on ductility and impact values were
indefinite. After heat treatment , strength and ductility
of the sub-criticaly annealed was superior to those after full
annealing ,but hardness was worse off. For both full
annealing and sub-critical annealing , the strength increased
and ductility decreased with section size ,but the effects on
impact values and hardness have no definite correlation.
Attempts were made to explain the mechanical behavior based on
microstructural features.