深冷處理對AISI D2冷作模具鋼變形量及磨耗行為之影響

Effect of Cryogenic Treatment on the Relative Length Change and Wear Behaviour of AISI D2 Cold-Work Die Steel

廖桓震(Huan-Chen Liao)

指導教授 ： 邱六合

大同大學/工程學院/材料工程學系所/碩士(2012年)

摘要

本研究針對12Cr之三種鋼廠所生產之類AISI D2鋼料之B材(寶鋼D2)、P材(Posco D2)及D材(天文大同DC53)進行不同真空熱處理及深冷處理，探討製程條件對微結構、硬度、尺寸變化及耐磨耗特性之影響，而試片在經過熱處理及深冷處理後還有些許殘留沃斯田體，隨著時間拉長，部分沃斯田體會慢慢轉變為穩定相的麻田散體，又因兩種組織比重不同，可能會造成模具產生體積膨脹所衍生之應力而造成破裂，為了觀察此現象對鋼材之影響，故施行經時變形觀察，每3個月量測其殘留沃斯田體含量及變形量。實驗試片使用1000~1050℃持溫20分鐘，進行2kg/cm2氮氣氣淬，深冷處理使用－90℃及－160℃，並於200~650℃區間進行不同溫度回火處理。X-ray分析得知試片經氣淬及回火後其主要結構均為回火麻田散體相，其間散佈有殘留沃斯田體及碳化物相。經氣淬後之試片因麻田散變態造成長度之增加，但隨著回火溫度上升，BCT的c軸縮短，導致尺寸縮小，直到400℃以上，伴隨著殘留沃斯田體變態及二次碳化物析出導致尺寸由縮小變增長。而經過深冷處理之試片，則可發現其長度增加變異相對安定。經深冷處理之磨耗試片可以提高對磨料磨耗的抵抗能力，但對黏著磨耗而言影響不大，其中以天文大同DC53有較佳的耐磨耗抵抗能力。經時變形結果顯示殘留沃斯田體量在六個月內，隨時間增長有下降的趨勢，但是變形量並未因殘留沃斯田體之下降，而造成體積增加。

關鍵字

殘留沃斯田體 ； 深冷處理 ； 磨耗

並列摘要

Three cold-work steeels, standard B, P(AISI D2) and modified D (DC53), have been vacuum heat treated by using different quenching and tempering processes to observe the change of microstructure, hardness, wear resistance and the relative length change. The conditions was austenitized at 1000~1050℃ for 20 min, cryogenic treatment at －90℃ and －160℃, and tempered at 200℃~650℃. The specimens always exist retained austenite after heat treatment and cryogenic treatment. A part of unstable retained austenite will be transformed into stable martensite with time, and further, retaned austenite and martensite have different volume so it will cause volume expansion or crack. In order to observe the effect of steels in the phenomenon, I measure the percent of retained austenite and the relative length change each 3 month. The results shows that wear resistance of modified D(DC53) was better than standard B and P(AISI D2). The percent of retained austenite will be decreased gradually in 6 months, but the relative length change was not unity.

並列關鍵字

retained austenite ； cryogenic treatment ； wear resistance

參考文獻

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