發(fā)布時(shí)間：2018-03-17 01:25

  本文選題：激光熔凝　切入點(diǎn)：HT300導(dǎo)軌　出處：《太原科技大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：近年來,激光表面改性技術(shù)與仿生耦合學(xué)相結(jié)合,廣泛應(yīng)用于導(dǎo)軌耐磨性能的改善中,成為一個(gè)研究熱點(diǎn),但是至今尚且存在一些不足,對磨損過程中內(nèi)部的應(yīng)力分析還很模糊。(1)為了提高導(dǎo)軌的耐磨性能,本文對HT300材質(zhì)的導(dǎo)軌進(jìn)行了激光熔凝處理。分析了激光熔凝前后HT300材質(zhì)的顯微形貌、組織結(jié)構(gòu)、顯微硬度、彈性模量和3D磨損形貌,從顯微組織和顯微硬度兩個(gè)層面總結(jié)了激光熔凝后耐磨機(jī)理。結(jié)果表明,HT300導(dǎo)軌經(jīng)激光熔凝后生成的馬氏體組織由于存在孿晶和位錯(cuò),增強(qiáng)了材質(zhì)抵抗塑性變形的能力。顯微硬度比原來提高了3.11倍,使得磨損過程中硬化區(qū)的粗糙峰承載著主要的應(yīng)力,減輕了基體所受應(yīng)力。XRD實(shí)驗(yàn)結(jié)果得出石墨含量降低量占基體的40%,降低了裂紋萌生率。激光處理區(qū)域經(jīng)過磨損后,錐刺、鱗尾、點(diǎn)蝕、剝落現(xiàn)象較未處理部位明顯降低,裂紋擴(kuò)展方向與摩擦方向呈45?-60?夾角,萌生源頭為基體與熔凝組織的銜接部位。(2)設(shè)計(jì)出不同仿生試樣,在相同的滾動(dòng)干磨擦情況下進(jìn)行磨損試驗(yàn),結(jié)合磨損失重情況和3D形貌得到最大化改善導(dǎo)軌耐磨性能的仿生織構(gòu)。在仿生織構(gòu)形狀相同的前提下,硬化區(qū)體積越大耐磨性越強(qiáng),主要?dú)w因于高硬度值。在織構(gòu)體積相同的前提下,不同類型的織構(gòu)在磨損過程中的等效應(yīng)力,最大剪應(yīng)力,摩擦應(yīng)力各不相同,因而耐磨性能也有所差異。(3)利用ansys workbench軟件對非線性摩擦學(xué)問題進(jìn)行了動(dòng)態(tài)接觸分析,從剪應(yīng)力、等效應(yīng)力、摩擦應(yīng)力三方面分析了仿生導(dǎo)軌內(nèi)部接觸應(yīng)力變化情況。動(dòng)態(tài)接觸分析結(jié)果表明試樣塊抗疲勞磨損的能力與實(shí)驗(yàn)結(jié)果分析中的變化趨勢基本一致,仿生織構(gòu)與摩擦方向所成的夾角越大,摩擦應(yīng)力越小。模仿穿山甲仿生試樣表面紋理織構(gòu)的耐磨性能較與摩擦方向呈角度的耐磨性能強(qiáng),仿生試樣能夠使接觸表面摩擦應(yīng)力變得平緩,從而使材料受力均勻。仿生織構(gòu)的存在改變了運(yùn)動(dòng)部件的應(yīng)力分布狀態(tài),降低了最大應(yīng)力分布面積。其夾角處(即激光搭接部位)容易產(chǎn)生應(yīng)力集中現(xiàn)象,而穿山甲試樣的圓弧能夠起到釋放應(yīng)力的作用,基于此得到了優(yōu)化耐磨性能的方案:避免激光搭接產(chǎn)生應(yīng)力集中和空洞現(xiàn)象,增加圓弧半徑使應(yīng)力得到釋放,對以后導(dǎo)軌的仿生強(qiáng)化具有一定的指導(dǎo)意義。
[Abstract]:In recent years, laser surface modification technology combined with bionic coupling technology has been widely used in improving the wear resistance of guideway. In order to improve the wear resistance of the guide rail, the laser melting and setting treatment of the HT300 material is carried out. The microstructure, microstructure and microhardness of the HT300 material before and after the laser melting are analyzed, and the results are as follows: (1) in order to improve the wear resistance of the guide rail, the microstructure, microstructure and microhardness of the HT300 material before and after laser melting are analyzed. Elastic modulus and 3D wear morphology, the wear resistance mechanism after laser melting is summarized from two aspects of microstructure and microhardness. The results show that the martensite structure of the HT300 rail formed by laser melting is due to the existence of twinning and dislocations. The ability of material to resist plastic deformation is enhanced. The microhardness is 3.11 times higher than before, which makes the rough peak of hardening zone bear the main stress during wear. The results of XRD experiment show that the content of graphite decreases by 40% of the matrix, and the crack initiation rate decreases. After the laser treatment area is worn, the phenomenon of cone prick, scaly tail, pitting and denudation is obviously lower than that of the untreated part. The direction of crack propagation and the direction of friction are 45? -60? Different bionic samples were designed and wear tests were carried out under the same rolling dry friction condition. The bionic texture which can improve the wear resistance of the guide rail is obtained by combining the wear weight loss and 3D morphology. The larger the volume of the hardened zone is, the stronger the wear resistance of the hardened zone is, when the shape of the bionic texture is the same. Under the premise of the same texture volume, the equivalent stress, maximum shear stress and friction stress of different types of texture in the process of wear are different. Therefore, the wear resistance is also different. (3) the dynamic contact analysis of nonlinear tribological problems is carried out by using ansys workbench software, and the shear stress and equivalent stress are analyzed from the point of view of shear stress and equivalent stress. The dynamic contact analysis results show that the resistance to fatigue wear of the sample block is basically consistent with the change trend in the analysis of experimental results. The larger the angle between bionic texture and friction direction, the smaller the friction stress. The biomimetic specimen can smooth the friction stress on the contact surface and make the material under uniform stress. The existence of bionic texture changes the stress distribution of moving parts. The maximum stress distribution area is reduced. The stress concentration is easy to occur at the angle (that is, the laser lap position), and the arc of the pangolin specimen can release the stress. Based on this, the scheme of optimizing wear-resisting performance is obtained: avoiding stress concentration and void phenomenon in laser lap connection, increasing arc radius to release stress, which has certain guiding significance for bionic strengthening of guide rail in the future.
【學(xué)位授予單位】：太原科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG665

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本文編號：1622557