本論文探討成份為鐵-10.6錳-0.64碳(wt％)之高錳鋼經不同溫度的熱處理後所產生的相變化情形。本高錳鋼是以自行熔煉鑄造的方式取得，再將鑄鋼經高溫均質化處理而後熱煅成鋼板。爾後的熱處理方式為高溫固溶處理以及低溫恆溫處理。本研究主要是以TEM分析此高錳鋼內部的結晶結構與相變化情形。
合金經1100℃固溶處理後，其相組成為沃斯田體基地相以及分布於沃斯田體基地內之麻田散體相。此麻田散體可分為兩類：一為具FCC結晶結構的微小雙晶；另一為具HCP結晶結構的麻田散體。此麻田散體可一直存在於經低溫時效處理的高錳鋼內。
經750℃恆溫處理後的高錳鋼內，晶界上開始有M3C碳化物的析出，且此晶界析出物亦有以板狀魏德曼組織的形式由沃斯田體基地的晶界處析出並向晶粒內生長。於750至500℃的溫度區間內，晶界上皆有M3C碳化物的存在，亦同時發現魏德曼M3C碳化物由晶界析出並向晶粒內生長。故高錳鋼內的M3C碳化物的析出上限溫度應介於775至750℃的溫度區間內。高錳鋼經675℃以下的溫度恆溫熱處理後，於沃斯田體基地有波來體組織之形成；且可於原ε-麻田散區域內發現肥粒體，此肥粒體之形貌呈不規則的破碎狀，明顯與波來體內的肥粒體晶粒不同。
高錳鋼於700℃以下的溫度恆溫處理後，我們也發現臨近板狀M3C魏德曼組織旁亦有層狀肥粒體晶粒的附著生成，此為飽和的沃斯田體晶粒分解為M3C碳化物與肥粒體晶粒的共析反應，然而此共析反應的生成物卻由層狀M3C與肥粒體晶粒所形成魏德曼組織取代由層狀M3C和肥粒體的組成波來體組織。

We have studied the phase transformations of a high manganese steel. The composition of the steel is Fe-10.6 Mn-0.64 C (wt%). We made the high manganese steel from ingot casting directly. The ingots were hot-forged into slabs. The slabs were cut into small steel specimens which were solution heat treated at 1100℃, and followed by isothermal heating at temperatures between 800 and 500℃.
The constituent phase of the high manganese steel at temperatures between 1100 and 775℃ is single austenite. However, the constituent phases in the solution treatment condition include the austenite and martensitic phases which distributed in the austenitic matrix. The martensitic phases include two different crystal structures. One is the HCP -martensite, the other is the FCC micro-twins. In the OM observation, both are in the form of irregular plates in the austenitic matrix. We found both martensitic phases exist in the specimen even at low temperatures.
We observed M3C carbide grains distribute at the austenitic grain boundaries at temperatures below 750℃. Thus, the upper temperature limit for the existence of the M3C carbide of the steel is between 775 and 750℃. In addition to grain boundary precipitates, the M3C carbide grains also in the form of Widmanstatten side-plates nucleated at the grain boundary areas and grew into the austenitic matrix. At temperatures between 750 and 500℃, we observed that the M3C carbide appears in the austenitic matrix in both morphologies, either grain boundary precipitates or Widmanstatten side-plates. We also found ferritic grains attached to the M3C Widmanstatten side-plates as the products of a different eutectoid reaction.
The traditional eutectoid reaction for the decomposition of austenite into ferrite and M3C carbide was discovered in the steel at temperatures below 675℃. In addition to the pearlitic colonies in the austenitic matrix, some other regions of austenitic grains transformed into small irregular ferritic grains. It is most probably due to the transformation of  into , i.e. the ferritic grains are most probably from the HCP -martensitic plates. The HCP -martensitic plates are from the gliding of the partial dislocation. When martensitic plates transformed into ferritic grains, shear stresses were accompanied with the new formed grains. It caused the new grains to deform, and irregular ferritic grains produced.

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