【摘要】：利用稀土元素與合金元素的優(yōu)勢互補(bǔ)作用,設(shè)計(jì)一種低成本高強(qiáng)韌鋼軌專用的Mn-Cr-Mo-La系貝氏體鋼,通過測定其動態(tài)連續(xù)冷卻轉(zhuǎn)變(CCT)曲線,研究相變行為及組織特征;基于現(xiàn)場鋼軌連軋工藝BD1-BD2-CCS進(jìn)行熱連軋模擬試驗(yàn),采用透射電鏡(TEM)觀察精細(xì)亞結(jié)構(gòu),分析試驗(yàn)鋼的組織細(xì)化和強(qiáng)韌化機(jī)理。結(jié)果表明:由于添加稀土元素可加強(qiáng)Mn、Cr、Mo的淬透性作用,試驗(yàn)鋼在冷速范圍0.8~2℃/s內(nèi)可獲得大量細(xì)小板條貝氏體;其熱連軋模擬后的精細(xì)組織為板條間帶有穩(wěn)定殘余奧氏體膜的無碳化物貝氏體,亞單元寬度細(xì)化至39~80nm,塊狀超細(xì)亞單元尺寸為20nm×32nm,板條內(nèi)發(fā)現(xiàn)2~20nm的微細(xì)孿晶和高密度位錯(cuò),使試驗(yàn)鋼抗拉強(qiáng)度達(dá)1 260 MPa,室溫下沖擊功達(dá)95J,該納米級貝氏體組織有利于阻礙裂紋擴(kuò)展,防止貝氏體鋼軌軌裂。
[Abstract]:Based on the complementary effect of rare earth elements and alloy elements, a Mn-Cr-Mo-La bainitic steel with low cost and high strength and toughness was designed. The (CCT) curve of dynamic continuous cooling transformation was measured. Study on phase change behavior and microstructure; Based on the field continuous rail rolling process (BD1-BD2-CCS), the hot continuous rolling simulation test was carried out. The fine substructure of the steel was observed by transmission electron microscopy (TEM), and the microstructure refinement and strengthening and toughening mechanism of the steel were analyzed. The results show that due to the addition of rare earth elements to enhance the hardenability of Mn,Cr,Mo, a large number of fine lath bainite can be obtained in the cooling rate range of 0.8 鈩，

本文編號：2348869