本文關(guān)鍵詞： CALDIE鋼 等溫淬火 Q-P Q-P-T　出處：《哈爾濱工業(yè)大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：本論文以CALDIE鋼這種典型的冷作模具鋼為研究對(duì)象,主要針對(duì)其現(xiàn)實(shí)工作中存在的易產(chǎn)生崩角的問(wèn)題,研究通過(guò)等溫淬火處理、Q-P處理、Q-P-T處理三種熱處理方式實(shí)現(xiàn)在不明顯降低硬度的前提下提高韌性的目標(biāo),并借助X射線衍射儀(XRD)、金相顯微鏡(OM)、掃描電鏡(SEM)、透射電鏡(TEM)等分析手段對(duì)CALDIE鋼組織和性能進(jìn)行了表征,探索了適合CALDIE鋼的最佳熱處理工藝。首先進(jìn)行等溫淬火處理時(shí),在260℃~300℃進(jìn)行等溫淬火生成下貝氏體組織,下貝氏體鐵素體為針狀;320℃等溫淬火生成羽毛狀組織為上貝氏體。對(duì)試樣X(jué)RD測(cè)試結(jié)果表明等溫淬火后殘余奧氏體含量在17%~24%之間,相同溫度下隨著保溫時(shí)間的延長(zhǎng),殘余奧氏體含量減少,表現(xiàn)出的力學(xué)性能特征為硬度下降,沖擊韌性上升。淬火后試樣沖擊韌性值為6.6J,在300℃保溫5h時(shí)沖擊韌性值達(dá)到最大11.8J,此時(shí)硬度值下降到HRC56以下。其次進(jìn)行Q-P處理可穩(wěn)定淬火后殘余奧氏體,經(jīng)XRD分析殘余奧氏體含量均分布在7%~10%之間,相同溫度下,隨著保溫時(shí)間的延長(zhǎng),更多的碳原子從馬氏體擴(kuò)散到奧氏體中,使奧氏體含碳量增大;殘余奧氏體含碳量在400℃碳分配5min時(shí)達(dá)到最大值為0.94%,而后繼續(xù)保溫由于碳分配過(guò)程已基本結(jié)束,后續(xù)發(fā)生了碳化物析出過(guò)程增大了碳的消耗,奧氏體含碳量下降到0.87%。Q-P處理后硬度值下降不大,韌性值也有提升,在400℃保溫5min時(shí)韌性值達(dá)到最大值9.2J,此時(shí)硬度值也在HRC58以上。最后,Q-P處理后在550℃回火1h,殘余奧氏體發(fā)生分解,殘余奧氏體含量已低于5%;由于回火過(guò)程析出了合金碳化物可起到強(qiáng)化作用,而馬氏體中碳含量降低又會(huì)使硬度下降,在兩種因素的共同作用下回火后試樣硬度值變化不大,由于主要韌性相奧氏體量的減少,韌性值發(fā)生了小幅度下降。經(jīng)等溫淬火以及Q-P和Q-P-T處理后試樣的韌性均得到了提升,在300℃保溫5h時(shí)沖擊韌性值達(dá)到最大11.8J,但硬度值下降較多;經(jīng)400℃保溫5min Q-P處理后韌性值可提高50%,硬度值下降不多,是適合提高CALDIE鋼韌性的熱處理工藝。
[Abstract]:In this paper, CALDIE steel, a typical cold working die steel, is taken as the research object. Aiming at the problem of easy to produce collapse angle in its practical work, the isothermal quenching treatment and Q-P treatment are studied in this paper. Q-P-T treatment of three heat treatment methods to achieve the goal of improving toughness without obviously reducing hardness, and by means of X-ray diffractometer XRDX, metallographic microscope OM). The microstructure and properties of CALDIE steel were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optimum heat treatment process suitable for CALDIE steel was explored. Firstly, when isothermal quenching was carried out, the lower bainite was formed by austempering at 260 鈩，

本文編號(hào)：1490850