本文選題：殘余應力 + 脈沖電流　； 參考：《浙江大學》2016年博士論文

【摘要】：本文結(jié)合國家自然科學基金項目"消除殘余應力的電擊法及其應用基礎研究"和航空科學基金項目"高精度加速度計穩(wěn)定化處理關(guān)鍵技術(shù)研究",對脈沖電流法調(diào)控碳鋼殘余應力的機理和相關(guān)實驗進行了研究。第一章闡述了論文的研究背景、意義和內(nèi)容。首先,分析了殘余應力的產(chǎn)生、分類、測量方法,以及對工件性能的影響,指出了調(diào)控殘余應力的重要意義;其次,評述了殘余應力調(diào)控技術(shù)和脈沖電流在材料處理中應用的研究現(xiàn)狀;然后,重點分析了脈沖電流法調(diào)控殘余應力的國內(nèi)外研究現(xiàn)狀,指出了現(xiàn)有研究中存在的不足;最后,提出了本文的研究內(nèi)容。第二章研究了基于多尺度力學理論的殘余應力松弛機理。首先,建立了殘余應力松弛的連續(xù)介質(zhì)力學模型,確定了宏觀彈塑性變形與殘余應力松弛的關(guān)系;然后,分別推導出了晶體切應變速率與位錯滑移和位錯密度之間的關(guān)系,以及晶粒彈塑性變形與殘余應力松弛之間的關(guān)系,解決了由微觀到宏觀的力學尺度轉(zhuǎn)換問題;最后,基于位錯牛頓力學模型、熱動力學模型和位錯密度演化規(guī)律,討論了位錯與殘余應力的相互作用。第三章研究了脈沖電流對碳鋼微觀結(jié)構(gòu)動態(tài)行為的作用機制。首先,建立了碳原子的電子拖拽力模型,分析了脈沖電流對淬火碳鋼試樣碳原子擴散、偏聚行為的影響規(guī)律;然后,建立了位錯的電子拖拽力模型,分析了電子拖拽力、Joule熱效應、微觀結(jié)構(gòu)對位錯動態(tài)行為的作用機制;最后,建立了脈沖電流對碳鋼馬氏體晶界作用的力學模型,討論了脈沖電流影響馬氏體形貌的機制,分析了脈沖電流法通過對微觀結(jié)構(gòu)動態(tài)行為的作用調(diào)控殘余應力的機理。第四章研究了趨膚效應對脈沖電流調(diào)控碳鋼殘余應力的影響。首先,根據(jù)Maxwell方程組,推導出了衰減振蕩脈沖電流通過矩形截面試樣時電場強度、電流密度的解析表達式;然后,分析了趨膚效應對碳原子和位錯受到的電子拖拽力的影響規(guī)律,討論了趨膚效應對殘余應力的影響。第五章實驗研究了脈沖電流法調(diào)控殘余應力的機理。首先,完善了脈沖電流法調(diào)控金屬試樣殘余應力的實驗系統(tǒng);然后,實驗研究了脈沖電流對淬火45鋼試樣力學性能的影響規(guī)律,主要包括殘余應力、拉伸性能、表面硬度;最后,實驗研究了脈沖電流對淬火45鋼試樣顯微組織形態(tài)的作用規(guī)律,主要包括碳原子分析、位錯密度、馬氏體微觀形貌。通過對脈沖電流對淬火45鋼試樣力學性能和顯微組織形態(tài)影響的研究,驗證了脈沖電流法調(diào)控殘余應力機理的正確性。第六章總結(jié)了本文的研究成果,并展望了今后需要進一步展開的研究工作。
[Abstract]:In this paper, the pulse current method is adjusted according to the project of the National Natural Science Foundation of China, "Electric shock method for eliminating residual stress and its application basic research" and the project "key technology of high precision accelerometer stabilization treatment", which is a project of aviation science foundation. The mechanism and experiment of residual stress of carbon steel were studied. The first chapter describes the research background, significance and content of the thesis. Firstly, the generation, classification, measurement method and effect on the performance of the workpiece are analyzed, and the significance of controlling the residual stress is pointed out. The research status of residual stress regulation technology and pulse current application in material treatment is reviewed. Then, the research status of pulse current method in controlling residual stress at home and abroad is analyzed, and the shortcomings of existing research are pointed out. The research content of this paper is put forward. In chapter 2, the mechanism of residual stress relaxation based on multi-scale mechanics is studied. Firstly, the continuum mechanics model of residual stress relaxation is established, and the relationship between macroscopic elastic-plastic deformation and residual stress relaxation is determined, and the relationship between crystal shear strain rate and dislocation slip and dislocation density is derived respectively. And the relationship between grain elastic-plastic deformation and residual stress relaxation solves the problem of mechanical scale conversion from microcosmic to macroscopic. Finally, based on dislocation Newtonian mechanics model, thermodynamics model and dislocation density evolution law, The interaction between dislocation and residual stress is discussed. In chapter 3, the mechanism of pulse current acting on microstructure dynamic behavior of carbon steel is studied. Firstly, the electronic drag force model of carbon atom is established, and the influence of pulse current on the diffusion and segregation behavior of carbon atom in quenched carbon steel sample is analyzed, and then the electronic drag force model of dislocation is established. The mechanism of the effect of electron tug force Joule thermal effect and microstructure on the dynamic behavior of dislocation is analyzed. Finally, a mechanical model of the effect of pulse current on martensite grain boundary of carbon steel is established, and the mechanism of pulse current affecting the morphology of martensite is discussed. The mechanism of controlling residual stress by pulse current method is analyzed. In chapter 4, the effect of skin effect on residual stress of carbon steel regulated by pulse current is studied. Firstly, according to the Maxwell equations, the analytical expressions of the electric field intensity and current density of the attenuated oscillating pulse current passing through the rectangular cross section sample are derived. The effect of skin effect on the electronic drag force of carbon atoms and dislocations is analyzed, and the effect of skin effect on residual stress is discussed. In chapter 5, the mechanism of residual stress regulation by pulse current method is studied experimentally. Firstly, the experimental system of controlling residual stress of metal specimen by pulse current method is improved, and then the influence of pulse current on mechanical properties of quenched 45 steel specimen is studied, including residual stress, tensile property and surface hardness. Finally, the effect of pulse current on microstructure of quenched 45 steel was studied, including carbon atom analysis, dislocation density and martensite morphology. The effect of pulse current on mechanical properties and microstructure of quenched 45 steel samples was studied and the correctness of residual stress control mechanism by pulse current method was verified. The sixth chapter summarizes the research results of this paper and looks forward to further research work in the future.
【學位授予單位】：浙江大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：TG142.1

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