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  本文關鍵詞： 馬氏體 殘留奧氏體 含碳量 中子衍射 高C-高Cr鋼　出處：《武漢科技大學》2015年碩士論文　論文類型：學位論文

【摘要】：本文主要研究高C-高Cr工具鋼中殘留奧氏體和馬氏體回火行為。淬火后的高C-高Cr工具鋼組織成分主要包括板條狀馬氏體、殘留奧氏體和碳化物。研究過程中將空冷淬火材和油冷淬火材在相同的回火條件下的實驗結果作對比分析，主要采用OM、SEM/EBSD和TEM等分析方法對高C-高Cr工具鋼的淬火材和回火材中的微觀組織進行觀察，并利用XRD和中子衍射等分析方法對殘留奧氏體的體積分數(shù)及殘留奧氏體和馬氏體中含碳量進行計算分析。同時也研究了各種熱處理條件下的材料硬度的變化。主要研究內容和結果如下： （1）在573K回火條件下，，塊狀殘留奧氏體通過從馬氏體中吸收碳原子從而使其體積分數(shù)增加，而條狀殘留奧氏體分解為鐵素體和滲碳體，表明塊狀殘留奧氏體和條狀殘留奧氏體有不同的回火特性； （2）在573-773K回火條件下，殘留奧氏體的總體積幾乎不變或略有上升，但此時的殘留奧氏體是亞穩(wěn)態(tài)的。當塊狀殘留奧氏體回火后冷卻至室溫時，其轉變成馬氏體的臨界回火溫度為773K； （3）由于亞穩(wěn)態(tài)殘留奧氏體轉變成馬氏體的行為受試樣形狀和大小的限制，因此按照轉變行為的難易程度來劃分，首先發(fā)生在TEM薄片試樣中，其次是在SEM/EBSD等塊狀試樣的表面層，最后才是塊狀試樣的中心層。TEM、SEM/EBSD、XRD和中子衍射實驗都證實這一結果。
[Abstract]:In this paper, the tempering behavior of residual austenite and martensite in high C- high Cr tool steel is studied. Residual austenite and carbides. The experimental results of air-cooled quenched and oil-cooled quenched materials under the same tempering conditions were compared and analyzed during the study. The microstructure of quenching and tempering materials of high C- high Cr tool steel was observed by OMSEM / EBSD and TEM. The volume fraction of retained austenite and the carbon content in retained austenite and martensite were calculated and analyzed by means of XRD and neutron diffraction. The contents and results of the study are as follows:. 1) at 573K tempering condition, bulk residual austenite increases its volume fraction by absorbing carbon atoms from martensite, while strip residual austenite decomposes into ferrite and cementite. The results show that the bulk retained austenite and the strip retained austenite have different tempering characteristics. (2) under the tempering condition of 573-773K, the total volume of retained austenite is almost unchanged or slightly increased, but the residual austenite is metastable. When the bulk residual austenite is cooled to room temperature after tempering, the critical tempering temperature for transformation to martensite is 773K; (3) since the transformation of metastable residual austenite to martensite is limited by the shape and size of the sample, the transformation behavior is divided according to the degree of difficulty of the transformation behavior, which occurs first in the TEM sheet specimen and then in the surface layer of the bulk specimen such as SEM/EBSD. Finally, the central layer of the bulk sample. TEMN SEM / EBSD XRD and neutron diffraction experiments both confirm this result.
【學位授予單位】：武漢科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TG142.1;TG156.5

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本文編號：1527933