本文選題：光整加工 + 滾磨　； 參考：《太原理工大學(xué)》2017年碩士論文

【摘要】：鈦合金TC4因其密度小、比強(qiáng)度高、耐腐蝕性能好,在航空航天、石油化工以及醫(yī)療等領(lǐng)域得到廣泛的應(yīng)用,但是由于硬度低以及疲勞性能偏差導(dǎo)致在很多方面限制了其進(jìn)一步的應(yīng)用。滾磨光整加工作為機(jī)械加工的終道加工工序,可以改變零部件表面完整性,提高零部件的抗疲勞性能。為此,本文以航空鈦合金材料TC4試件為研究對(duì)象,采用仿真與實(shí)驗(yàn)結(jié)合的方法,對(duì)臥式離心滾磨光整TC4試件進(jìn)行了系統(tǒng)研究,以改善試件表面完整性,進(jìn)而提高其抗疲勞性能。首先,通過ABAQUS對(duì)板材進(jìn)行靜強(qiáng)度分析,基于多元正交回歸分析方法與FE-SAFE疲勞壽命仿真對(duì)影響板材疲勞性能的顯著因素粗糙度、殘余應(yīng)力、外載應(yīng)力等因素做了定性分析并確定裂紋萌生的初始位置,繼而采用ABAQUS6.11集成的裂紋擴(kuò)展有限元方法對(duì)裂紋擴(kuò)展路徑做了仿真模擬并與實(shí)驗(yàn)對(duì)比,證明了仿真的正確性。其次,采用三因素四水平的正交實(shí)驗(yàn)方法對(duì)臥式離心滾磨光整加工板材單面及雙面進(jìn)行了實(shí)驗(yàn)研究,得到不同工藝參數(shù)對(duì)表面完整性參數(shù)的影響規(guī)律;單面加工時(shí),加工時(shí)間為60min,磨塊直徑為10mm,裝入量為80%;雙面加工時(shí),磨塊直徑為5mm,加工時(shí)間為15min,裝入量為80%,材料去除量最大;無論是單面加工還是雙面加工,磨塊直徑為7mm,加工時(shí)間為45min,裝入量為60%,表面粗糙度下降值最大;磨塊直徑為10mm,裝入量為60%,加工時(shí)間為30min時(shí),殘余壓應(yīng)力最大。在此基礎(chǔ)上,采用綜合平衡法得到了表面完整性較優(yōu)的工藝參數(shù):磨塊直徑7mm,加工時(shí)間45min,裝入量60%。最后,進(jìn)行了單雙面光整加工后試件的拉-拉疲勞實(shí)驗(yàn),得出雙面加工之后試件的疲勞壽命略大于單面加工之后試件的疲勞壽命;基于階梯級(jí)固定應(yīng)力水平下單雙面加工板材疲勞壽命結(jié)果,采用多元線性回歸分析的方法,擬合出粗糙度、硬度、殘余應(yīng)力、應(yīng)力水平對(duì)疲勞壽命的影響關(guān)系,通過回歸分析和方差分析驗(yàn)證了公式的正確性;采用公式計(jì)算出了未經(jīng)滾磨光整加工試件疲勞極限為289MPa,單面滾磨加工之后試件的疲勞極限為450MPa,較加工前疲勞極限提高15.7%;雙面加工之后疲勞極限為578MPa,較加工前疲勞極限提高48.5%。進(jìn)而通過觀察斷口形貌以及金相組織對(duì)抗疲勞機(jī)理進(jìn)行了分析,可以看出加工前后組織細(xì)化且裂紋萌生于次表層而非表層;通過XRD衍射實(shí)驗(yàn)可以看出衍射峰發(fā)生偏移,說明滾磨光整加工引入殘余壓應(yīng)力可抑制裂紋萌生以及擴(kuò)展從而提高疲勞壽命。本文得到了臥式離心滾磨光整加工TC4試件以提高其表面完整性較優(yōu)的工藝參數(shù),提高了鈦合金的疲勞性能;研究成果對(duì)于離心式滾磨光整加工鈦合金類零部件工藝參數(shù)選取提供了依據(jù),為鈦合金材料進(jìn)一步的應(yīng)用提供了參考。
[Abstract]:Titanium alloy TC4 has been widely used in aerospace, petrochemical and medical fields because of its low density, high specific strength and good corrosion resistance. However, its further application is limited in many respects due to its low hardness and fatigue performance deviation. As the finishing process of mechanical machining, the surface integrity of parts can be changed and the fatigue resistance of parts can be improved. Therefore, in this paper, the TC4 specimen of aviation titanium alloy is taken as the research object, and the horizontal centrifugal rolling finishing TC4 specimen is systematically studied by the method of simulation and experiment, in order to improve the surface integrity of the specimen and improve its fatigue resistance. Firstly, the static strength of plate is analyzed by Abaqus. Based on multivariate orthogonal regression analysis and FE-SAFE fatigue life simulation, the roughness and residual stress are analyzed. The external load stress and other factors are qualitatively analyzed and the initial position of crack initiation is determined. Then the crack propagation path is simulated by using Abaqus 6.11 integrated crack propagation finite element method and compared with the experimental results, which proves the correctness of the simulation. Secondly, the orthogonal experiment method of three factors and four levels is used to study the effect of different process parameters on the surface integrity parameters of horizontal centrifugal rolling finishing plate, and the influence of different process parameters on the surface integrity parameters is obtained. The processing time is 60 minutes, the diameter of the grinding block is 10 mm, the loading is 80 mm, and the diameter of the grinding block is 5 mm, the processing time is 15 minutes, the loading amount is 80 minutes, and the material removal is the largest, whether it is on one side or on both sides, The grinding block diameter is 7 mm, the processing time is 45 minutes, the loading amount is 60 minutes, and the surface roughness decrease value is the largest, while the grinding block diameter is 10 mm, the loading volume is 60 mm, and the processing time is 30min, the residual compressive stress is the largest. On this basis, the optimum surface integrity parameters were obtained by comprehensive balance method: grinding block diameter 7 mm, processing time 45 min, loading volume 60 mm. Finally, the tensile and tensile fatigue tests of single and double-sided finishing specimens are carried out, and it is concluded that the fatigue life of the specimen after double-sided finishing is slightly longer than that of the specimen after single-sided finishing. Based on the results of fatigue life of single and double machined plate under the fixed stress level of step, the influence of roughness, hardness, residual stress and stress level on fatigue life is fitted by the method of multiple linear regression analysis. The correctness of the formula is verified by regression analysis and variance analysis. The fatigue limit of unpolished specimen is 289MPa, the fatigue limit of single surface grinding is 450 MPa, the fatigue limit is 15.7 higher than that of pre-machining, and the fatigue limit of double-sided machining is 578MPa, which is 48.5% higher than that of pre-machining. By observing the fracture morphology and the anti-fatigue mechanism of metallographic structure, it can be seen that the microstructure is fine and the crack originates in the subsurface layer but not the surface layer before and after processing, and the diffraction peak is offset by XRD diffraction experiment. It is shown that the crack initiation and propagation can be inhibited and the fatigue life can be improved by the introduction of residual compressive stress in rolling finishing. In this paper, the process parameters of surface integrity of TC4 specimens processed by horizontal centrifugal rolling finishing are obtained, and the fatigue properties of titanium alloys are improved. The research results provide a basis for the selection of technological parameters for the centrifugal rolling finishing of titanium alloy parts, and provide a reference for the further application of titanium alloy materials.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG580.6;TG146.23

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本文編號(hào)：2007195