本文選題：激光熔碳 + 耦合仿生��； 參考：《吉林大學(xué)》2017年碩士論文

【摘要】：鐵路鋼軌作為鐵路運(yùn)輸中重要的組成部件,其質(zhì)量和性能直接影響鐵路運(yùn)輸?shù)陌踩托�。隨著我國(guó)客運(yùn)高鐵的飛速發(fā)展和貨運(yùn)鐵路運(yùn)輸量的逐漸提高,鐵路鋼軌的疲勞磨損日益嚴(yán)重,導(dǎo)致了其服役時(shí)間逐漸縮短。為了保證鐵路運(yùn)輸?shù)男熊嚢踩?并盡量降低鐵路運(yùn)營(yíng)的成本,我們需要盡可能地提高鐵路鋼軌的抗?jié)L動(dòng)疲勞磨損性能,延長(zhǎng)其服役時(shí)間。根據(jù)以往的研究,通過激光仿生熔凝技術(shù)在基體材料表面制備出高硬度的仿生單元體,高硬度的單元體和低硬度的基體材料形成一種類似于生物體表的軟硬相間的耦合仿生結(jié)構(gòu),能有效提升基體材料表面抗?jié)L動(dòng)疲勞磨損性能。如果進(jìn)一步提高仿生單元體的硬度,有可能進(jìn)一步提高表面抗?jié)L動(dòng)疲勞磨損性能。本文采用激光熔碳的方式對(duì)U71Mn鋼進(jìn)行處理,制備比熔凝單元體硬度更高的熔碳單元體,使其在滾動(dòng)磨損中承受更大的應(yīng)力,從而進(jìn)一步提高仿生試樣表面的抗?jié)L動(dòng)疲勞磨損性能。研究表明:經(jīng)過激光加工處理的仿生試樣比未處理試樣具有優(yōu)異的抗?jié)L動(dòng)疲勞磨損性能。相比于激光熔凝處理的仿生試樣,激光熔碳處理的仿生試樣具有更好的抗?jié)L動(dòng)疲勞磨損性能。根據(jù)對(duì)生物模型的簡(jiǎn)化并再設(shè)計(jì),可發(fā)現(xiàn)激光熔碳處理的具有網(wǎng)格狀單元體的仿生試樣抗磨損性能最佳,其磨損失重量相比于未處理試樣降低了82%。由于激光熔碳處理,外部的碳元素進(jìn)入到單元體內(nèi),使得單元體整體碳含量提升,從而造成晶格畸變。相比于熔凝單元體,熔碳單元體內(nèi)碳含量高,易形成高碳馬氏體組織,使其顯微硬度更高,抗塑性變形能力更強(qiáng),得到了進(jìn)一步強(qiáng)化。在磨損實(shí)驗(yàn)中,高硬度的熔碳單元體能夠承受更多的應(yīng)力,使得基體部分所承受的應(yīng)力減少,提升磨損試樣的抗?jié)L動(dòng)疲勞磨損性能。當(dāng)涂覆碳層厚度不變,激光參數(shù)逐步增大時(shí),仿生試樣的抗?jié)L動(dòng)疲勞磨損性能將會(huì)出現(xiàn)拋物線式的變化;同時(shí),涂覆碳層厚度的減小會(huì)導(dǎo)致使用相同激光參數(shù)處理試樣的抗?jié)L動(dòng)疲勞磨損性能得到提高。
[Abstract]:As an important component of railway transportation, rail quality and performance directly affect the safety and efficiency of railway transportation. With the rapid development of China's passenger high-speed rail and the gradual improvement of freight rail transport volume, the fatigue wear of railway rail is becoming more and more serious, which results in the shortening of service time. In order to ensure the safety of railway transportation and reduce the cost of railway operation as far as possible, we need to improve the rolling fatigue wear resistance of railway rail as much as possible and prolong its service time. Based on previous studies, a high hardness bionic unit was fabricated on the surface of the substrate by laser bionic solidification. The high hardness unit and the low hardness matrix form a kind of coupling bionic structure similar to the biological table, which can effectively improve the rolling fatigue wear resistance of the substrate surface. If the hardness of the biomimetic unit is further improved, the rolling fatigue wear resistance of the surface may be further improved. In this paper, the U71Mn steel was treated by laser melting carbon, and the melting carbon unit with higher hardness than the melting unit was prepared, which made it bear more stress in rolling wear. Thus, the rolling fatigue wear resistance of the biomimetic specimen surface is further improved. The results show that the biomimetic specimen processed by laser has better rolling fatigue wear resistance than the untreated sample. Compared with the biomimetic specimen treated by laser melting, the bionic specimen treated by laser melting carbon has better rolling fatigue wear resistance. According to the simplification and redesign of the biological model, it can be found that the biomimetic specimen with grid element treated by laser melting carbon has the best wear resistance, and its wear loss weight is reduced by 82% compared with the untreated sample. As a result of laser carbon melting, the external carbon elements enter into the unit, which makes the whole carbon content of the unit increase, resulting in lattice distortion. Compared with the melting unit, the carbon content in the carbon melting unit is high, and the high carbon martensite structure is easy to form, which makes it have higher microhardness and stronger resistance to plastic deformation, which has been further strengthened. In the wear test, the high hardness carbon melting unit can withstand more stress, which can reduce the stress of the matrix and improve the rolling fatigue wear resistance of the wear specimen. When the thickness of the coated carbon layer is constant and the laser parameters increase gradually, the rolling fatigue wear resistance of the biomimetic specimen will be changed in a parabolic manner. The decrease of the thickness of the coated carbon layer will improve the rolling fatigue wear resistance of the samples treated with the same laser parameters.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG174.4;TG142.12

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本文編號(hào)：2018251