發(fā)布時(shí)間：2020-12-28 07:05

　　本文研究了激光功率、過渡層厚度、復(fù)合過渡層和激光偏置等對Ti6Al4V合金與304不銹鋼激光焊接接頭的影響規(guī)律。采用掃描電子顯微鏡（SEM）、能譜（EDS）、X射線衍射（XRD）和電子背散射衍射（EBSD）等分析方法表征了焊接接頭的斷裂特征。研究結(jié)果表明,接頭強(qiáng)度和斷裂位置取決于激光功率。在激光功率為4 kW下獲得的接頭最大抗拉強(qiáng)度達(dá)到300兆帕,為最優(yōu)功率。當(dāng)激光功率超過4 kW時(shí),接頭抗拉強(qiáng)度下降。與激光功率為3 kW和6 kW的焊接接頭相比,4 kW的焊接接頭斷裂表面與鈦合金之間距離的增加,且較多的銅殘留在鈦合金板上,這表明在該功率下銅原子可以較遠(yuǎn)的滲入到鈦合金表面從而提高鈦合金與銅過渡層的結(jié)合強(qiáng)度。斷口分析表明,與激光功率為3 kW和6 kW的焊接接頭相比,4 kW的焊接接頭的斷裂面更粗糙。XRD結(jié)果表明,在4 kW焊接接頭的斷裂面上形成了αTi,（V）和（Ni）等固溶體相。4 kW的焊接接頭的金屬間化合物（IMCs）具有最大的厚度,其中包含不連續(xù)的脆性化合物和一些較軟的鈦-銅金屬間化合物（IMCs）,從而導(dǎo)致其機(jī)械強(qiáng)度高于其他樣品。EBSD觀察表明IMCs層的厚度和接頭強(qiáng)度之... 

【文章來源】：上海交通大學(xué)上海市 211工程院校 985工程院校 教育部直屬院校

【文章頁數(shù)】：182 頁

【學(xué)位級別】：博士

【文章目錄】：
摘要
ABSTRACT
Chapter1 Introduction
    1.1 Phase microstructure in Fe-Ti phase diagram
    1.2 Application of Ti-SS joints
    1.3 Difficulties of direct joining Ti-SS
        1.3.1 Brittle intermetallics
        1.3.2 Difference in thermal expansion
        1.3.3 Difference in heat conductivity
    1.4 How to prevent brittle IMCs formation
    1.5 Interlayer engineering
    1.6 Interlayer suggestion for Ti-SS welding
        1.6.1 Single interlayer suggestion
        1.6.2 Composite interlayer suggestion
    1.7 Cu interlayer
    1.8 Solidification of MZ
    1.9 Computational thermodynamics
    1.10 Welding processes for Ti-SS joining
        1.10.1 Fusion welding
            1.10.1.1 Cold metal transfer
            1.10.1.2 Laser welding
            1.10.1.3 Laser-arc welding
            1.10.1.4 Electron beam welding
        1.10.2 Diffusion bonding
        1.10.3 Friction stir welding
        1.10.4 Explosive welding
        1.10.5 Brazing
        1.10.6 Roll welding
    1.11 Recent investigations on Ti-SS joints
    References
Chapter2 Experimental procedure
    2.1 Materials
    2.2 Sample preparation before welding
    2.3 Fiber laser welding equipment
    2.4 Sample preparation for microstructural observation
    2.5 Scanning electron microscope characterization
    2.6 X-ray diffraction characterization
    2.7 Electron backscatter diffraction characterization
    2.8 Mechanical testing
        2.8.1 Tensile testing
        2.8.2 Microhardness testing
    2.9 Offsetting
    2.10 Computational thermodynamics
    References
Chapter3 Enhanced mechanical strength of laser-welded joints of Ti6Al4V-304 SS by controlling heat input:experimental characterizations and thermodynamic simulations
    3.1 Direct welding of Ti6Al4V-304 SS by laser
    3.2 Weldability of Ti6Al4V-304 SS through single interlayers
    3.3 Mechanical properties of the joints
    3.4 Interface analysis
    3.5 Microstructure examination
    3.6 Characterization of fracture path edges
    3.7 Fractography
    3.8 Fracture Characterization
    3.9 Thermodynamic simulation of microstructural evolution
    3.10 Intermetallic layer thickness measurement
    Conclusion
    References
Chapter4 Intermediate interlayer thickening for development of laser-welded Ti6Al4V-304 SS joint strength
    4.1 Introduction
    4.2 An investigation based on single interlayer
        4.2.1 Mechanical properties of the joints
        4.2.2 Microstructure examination
        4.2.3 Fracture characterization
        4.2.4 Edge characterization after fracture
    4.3 An investigation based on double interlayers
    Conclusion
    References
Chapter5 High strength in Ti6Al4V-304 SS laser welded joints through the use of composite interlayers
    5.1 Introduction
    5.2 The weld beam appearance of composite interlayer experiments
    5.3 An investigation based on0.5 mm thick Cu
        5.3.1 Mechanical properties of the joints
        5.3.2 Fracture characterization
        5.3.3 Edge characterization after fracture
    5.4 An investigation based on1 mm thick Cu
    Conclusion
    References
Chapter6 Tailored mechanical strength of laser Ti6Al4V-304 SS weldments by offsetting
    6.1 Introduction
    6.2 Investigation based on single interlayer
        6.2.1 Mechanical properties of the joints
        6.2.2 Fracture characterization
        6.2.3 Edge characterization after fracture
    6.3 Investigation based on double interlayer
        6.3.1 Mechanical properties of the joints
        6.3.2 Fracture characterization
        6.3.3 Edge characterization after fracture
    Conclusion
    References
Chapter7 Relationship between the joint strength and potential compound（s）around the fracture path of Ti6Al4V-304 SS weldments
    References
Chapter8 Conclusion
    8.1 Conclusion
    8.2 Innovations
Acknowledgement
Publications


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期刊論文
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