本文選題：轉(zhuǎn)向架 + 鑄鋼��； 參考：《哈爾濱理工大學(xué)》2017年碩士論文

【摘要】：隨著新時(shí)期對(duì)鐵路運(yùn)輸提速重載新要求的提出,我國(guó)現(xiàn)有的轉(zhuǎn)向架用鋼已經(jīng)不能滿足鐵路貨車對(duì)轉(zhuǎn)向架性能的要求,而現(xiàn)有的高性能鑄鋼由于合金化程度較高,導(dǎo)致生產(chǎn)成本居高不下,因此有必要研究開發(fā)一種新的轉(zhuǎn)向架用鋼,使之在具有高性能的同時(shí)降低生產(chǎn)成本。課題在北美AAR標(biāo)準(zhǔn)B+級(jí)鑄鋼的成分范圍內(nèi),通過研究Mn、Cr、Ni和C元素含量以及正火溫度對(duì)鑄鋼組織和性能的影響規(guī)律,成功開發(fā)出一種新鑄鋼并確定了新鑄鋼最佳正火溫度,并且建立了鑄鋼成分、組織和性能之間的數(shù)學(xué)關(guān)系模型,使新鑄鋼在滿足AAR標(biāo)準(zhǔn)正火C級(jí)鋼性能要求的前提下,降低了生產(chǎn)成本。試驗(yàn)結(jié)果表明:隨著鑄鋼中Mn含量的增加,鑄鋼中珠光體含量升高、片間距減小,鑄鋼的強(qiáng)度升高,但塑韌性降低,在Mn含量為0.9 wt.%時(shí),鑄鋼的強(qiáng)韌性組合最佳;隨著鑄鋼中Cr含量的升高,鑄鋼中珠光體含量升高,鑄鋼的強(qiáng)度升高,硬度升高,并在Cr含量為0.3 wt.%時(shí),鑄鋼具有最佳的強(qiáng)韌性組合;鑄鋼中的Ni可有效細(xì)化鑄鋼的基體組織,提高鑄鋼的強(qiáng)韌性,但當(dāng)鑄鋼中Ni含量超過0.3 wt%時(shí),Ni含量的升高對(duì)鑄鋼性能的強(qiáng)化效果已經(jīng)不明顯;隨著鑄鋼中C含量的升高,鑄鋼的強(qiáng)度、硬度以及珠光體含量均升高,當(dāng)C含量由0.25 wt.%提高到0.31 wt.%時(shí),鑄鋼的抗拉強(qiáng)度由545 MPa提高到616 MPa,但韌性急劇降低,延伸率由31.4%降低到了24.8%;試驗(yàn)最終確定的鑄鋼成分為:C含量為0.27 wt.%,Mo含量為0.1 wt.%,Si含量為0.4 wt.%,Mn含量為0.9 wt.%,Cr含量為0.3 wt.%,Ni含量為0.3 wt.%,此時(shí)新鑄鋼碳當(dāng)量為0.56(CE=0.56),滿足鑄鋼焊接性能方面的要求;對(duì)鑄鋼進(jìn)行不同加熱溫度的正火熱處理,結(jié)果表明:鑄鋼隨著正火溫度的升高,鑄鋼的強(qiáng)度、硬度、沖擊吸收功均先升高后降低,延伸率幾乎不變;在正火加熱溫度為900℃時(shí),鑄鋼的強(qiáng)度最高,強(qiáng)韌性組合達(dá)到最佳,此時(shí)鑄鋼的抗拉強(qiáng)度為652.3 MPa,屈服強(qiáng)度為438.2 MPa,延伸率為24.3%,夏比V型缺口試樣在-18℃的沖擊吸收功為34.3 J,滿足AAR標(biāo)準(zhǔn)正火C級(jí)鋼的性能要求。
[Abstract]:With the raising of new requirements for railway transportation speed and heavy load in the new period, the existing bogie steel in China can no longer meet the requirements of railway freight cars for bogie performance, while the existing high performance cast steel is due to high alloying degree. Therefore, it is necessary to develop a new bogie steel to reduce the production cost while having high performance. In this paper, a new cast steel has been successfully developed and the optimum normalizing temperature has been determined by studying the influence of the contents of mn, Cr, Ni and C elements and normalizing temperature on the microstructure and properties of cast steel in the composition range of AAR class B cast steel in North America. A mathematical model of the relationship among composition, microstructure and properties of cast steel was established, which reduced the production cost of newly cast steel on the premise of satisfying the performance requirements of normalizing C grade steel of AAR standard. The experimental results show that with the increase of mn content in cast steel, the pearlite content in cast steel increases, the sheet spacing decreases, and the strength of cast steel increases, but the ductility decreases. When mn content is 0.9 wt.%, the strength and toughness combination of cast steel is the best. With the increase of Cr content in cast steel, the pearlite content in cast steel increases, the strength and hardness of cast steel increase, and when Cr content is 0.3 wt.%, cast steel has the best combination of strength and toughness, and Ni in cast steel can effectively refine the matrix structure of cast steel. The strength and toughness of cast steel were improved, but when the Ni content in cast steel exceeded 0.3 wt%, the strengthening effect of cast steel was not obvious, and the strength, hardness and pearlite content of cast steel increased with the increase of C content in cast steel. The tensile strength of cast steel increased from 545 MPa to 616 MPA when the content of C increased from 0.25 wt.% to 0.31 wt.%, but the toughness decreased sharply. The elongation of cast steel was reduced from 31.4% to 24.80.The composition of cast steel was determined to be:% C 0.27 wt.Mo 0.1wt.Si 0.4wt. mn 0.9 wt.cr 0.3 wt.Ni 0.3 wt.The carbon equivalent of newly cast steel is 0.56 CE0.56, which meets the requirements of welding properties of cast steel. The normalizing heat treatment of cast steel at different heating temperatures shows that the strength, hardness and impact absorption energy of cast steel increase first and then decrease with the increase of normalizing temperature, and the elongation of cast steel is almost unchanged when normalizing heating temperature is 900 鈩，

本文編號(hào)：1796030