本文關鍵詞： GCr15軸承鋼 球化 奧氏體化 碳化物溶解 碳化物粗化 晶粒長大　出處：《上海交通大學》2015年碩士論文　論文類型：學位論文

【摘要】：滾動軸承是機械裝備的關鍵基礎件,其使用壽命與熱處理有著密切的關系。GCr15軸承鋼是使用最為廣泛的高碳鉻軸承鋼,本文圍繞GCr15軸承鋼熱處理工藝的制訂,采用光學顯微鏡、掃描電子顯微鏡、力學性能測試等方法,研究了GCr15軸承鋼的球化處理工藝和奧氏體化工藝。為了獲得細小、圓整、均勻分布的碳化物顆粒,以高溫固溶為預處理手段,系統(tǒng)研究了加熱溫度、保溫時間及冷卻方式對高溫回火和低溫雙相退火兩類球化工藝所得組織中碳化物顆粒的形貌及尺寸分布的影響,并探討了兩類工藝的球化機制。高溫回火工藝的球化機制主要為淬火馬氏體在高溫回火過程中碳化物的析出、長大與球化,最佳工藝參數(shù)為740℃×2 h;低溫雙相退火工藝的球化機制主要是在低溫雙相奧氏體區(qū)的初步球化和隨后離異共析轉(zhuǎn)變過程中的進一步球化,最佳奧氏體化工藝參數(shù)為780℃×30 min,離異共析轉(zhuǎn)變工藝參數(shù)為25℃/h連續(xù)退火或720℃×4 h等溫退火。奧氏體化過程中碳化物的溶解、粗化和奧氏體晶粒的長大對GCr15軸承鋼的最終組織性能有很大影響。本文通過碳化物溶解與粗化過程的迭代計算,建立了碳化物的溶解與粗化模型,并能夠較準確地預測奧氏體化過程中碳化物顆粒的平均粒徑和體積分數(shù)變化;此外,本文在試驗基礎上研究了奧氏體晶粒的長大規(guī)律,當奧氏體化溫度低于900℃時,由于未溶碳化物顆粒的阻礙,晶粒尺寸隨奧氏體化溫度和保溫時間的變化較小。最后,本文研究了固溶-高溫回火、固溶-連續(xù)退火和固溶-等溫退火三種球化工藝對淬回火后組織與性能的影響。與傳統(tǒng)球化工藝相比,三種球化工藝均能有效提高GCr15軸承鋼的抗彎強度,其中固溶-連續(xù)退火工藝為最佳工藝。
[Abstract]:Rolling bearing is the key part of mechanical equipment, and its service life is closely related to heat treatment. GCr15 bearing steel is the most widely used high carbon chromium bearing steel. In this paper, the heat treatment process of GCr15 bearing steel is formulated and optical microscope is used. The spheroidization and austenitization of GCr15 bearing steel were studied by means of scanning electron microscope (SEM) and mechanical property test. In order to obtain fine, round and uniformly distributed carbide particles, high temperature solution was used as the pretreatment method. The effects of heating temperature, holding time and cooling mode on the morphology and size distribution of carbides in the spheroidized microstructure obtained by high temperature tempering and low temperature dual phase annealing were systematically studied. The spheroidization mechanism of two kinds of processes is discussed. The spheroidization mechanism of high temperature tempering process is mainly the precipitation, growth and spheroidization of quenched martensite during high temperature tempering. The optimum technological parameters are 740 鈩，

本文編號：1517290