發(fā)布時(shí)間：2018-06-03 22:43

  本文選題：20MnCrNi2Mo耐磨鑄鋼 + 鑭��； 參考：《內(nèi)蒙古科技大學(xué)》2015年碩士論文

【摘要】：低合金耐磨鑄鋼性能優(yōu)良且生產(chǎn)成本低，是一類很有發(fā)展前途的耐磨材料，稀土在低合金耐磨鑄鋼中的應(yīng)用也備受關(guān)注。以貝氏體為主要組織的低合金耐磨鑄鋼是我國(guó)近年來(lái)研究的一個(gè)方向，采用多元合金化并通過適當(dāng)?shù)臒崽幚硗瑫r(shí)提高韌性和硬度，對(duì)提高耐磨性尤為重要。有關(guān)貝氏體的回火過程，已經(jīng)開展了大量工作，但粒狀貝氏體的回火轉(zhuǎn)變還有待深入研究，且稀土對(duì)貝氏體回火轉(zhuǎn)變的影響少見報(bào)道。因此，研究粒狀貝氏體的回火過程，并弄清稀土的影響，不僅具有重要的理論研究意義，而且具有重要的工程應(yīng)用價(jià)值。 本文針對(duì)添加不同含量鑭、鈰混合稀土的20MnCrNi2Mo耐磨鑄鋼，對(duì)其鑄態(tài)組織進(jìn)行200、250、300、350、400、450、500、550、600和650℃各自保溫1h的回火處理。采用洛氏硬度計(jì)測(cè)定回火后的硬度；采用SEM、TEM及配備的EDS對(duì)回火組織進(jìn)行觀察；采用電解提取+XRD對(duì)回火過程中的析出相進(jìn)行定性分析；采用XRD對(duì)回火過程中殘留奧氏體量進(jìn)行定量分析；通過非水電解液低溫電解分離稀土夾雜物，采用ICP-MS測(cè)定稀土固溶量，采用TEM及EDS對(duì)固溶稀土存在位置進(jìn)行探索。研究20MnCrNi2Mo耐磨鑄鋼貝氏體的回火轉(zhuǎn)變及稀土的影響，探討稀土的作用機(jī)理。 結(jié)果表明：20MnCrNi2Mo耐磨鑄鋼粒狀貝氏體200～650℃保溫1h的回火過程中，觀察到250℃回火時(shí)M/A島發(fā)生分解，350℃回火時(shí)M/A島數(shù)量明顯減少；回火過程中析出的碳化物為M3C型；500℃回火時(shí)觀察到有亞晶形成，但邊界模糊，650℃回火時(shí)亞晶變得清晰可見。添加稀土，將回火過程中M/A島的分解推向高溫，析出相的類型未變，但稀土阻礙合金元素向Fe3C中擴(kuò)散富集，稀土抑制回火過程中亞晶的形成。測(cè)定結(jié)果表明稀土在20MnCrNi2Mo耐磨鑄鋼中有微量固溶，固溶稀土易于偏聚在晶界等缺陷處，阻礙碳及合金元素的擴(kuò)散，，對(duì)位錯(cuò)運(yùn)動(dòng)也會(huì)產(chǎn)生阻礙作用，影響了粒狀貝氏體回火過程中組織與硬度的變化。
[Abstract]:Low alloy wear-resistant cast steel is a kind of wear-resistant material with good properties and low production cost. The application of rare earth in low-alloy wear-resistant cast steel is also concerned. Low alloy wear-resistant cast steel with bainite as the main structure is a research direction in China in recent years. It is very important to improve wear resistance by adopting multi-element alloying and improving toughness and hardness simultaneously through proper heat treatment. A lot of work has been done on the tempering process of bainite, but the tempering transformation of granular bainite needs further study, and the effect of rare earth on bainite tempering transformation is rarely reported. Therefore, studying the tempering process of granular bainite and understanding the influence of rare earth are not only of great theoretical significance, but also of great engineering application value. In this paper, the as-cast microstructure of 20MnCrNi2Mo wear-resistant cast steel with different contents of lanthanum and cerium was tempered at 200250300350400450500550600 鈩

本文編號(hào)：1974533