本文選題：激光沉積制造/修復(fù)　切入點(diǎn)：TA15鈦合金　出處：《沈陽航空航天大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：激光沉積制造技術(shù)利用“離散+堆積”的增材成形思想,采用同軸送粉和激光熔覆數(shù)字化成形進(jìn)一步控制工件的成形精度,然而在成形過程中由于激光的高密度能量累積以及散熱方向的單一性,導(dǎo)致成形件組織分布不均勻,力學(xué)性能出現(xiàn)各向異性。熱處理工藝具有調(diào)節(jié)顯微組織和改善力學(xué)性能等作用,因此將熱處理工藝應(yīng)用于激光沉積制造成形件。由于激光沉積制造技術(shù)的特殊性,導(dǎo)致其與傳統(tǒng)鍛造或鑄造等方法的組織明顯不同,致使熱處理工藝需要重新摸索和制定。激光沉積制造技術(shù)包含激光沉積制造和激光沉積修復(fù)兩種方式,兩種方式需要截然不同的熱處理工藝。對(duì)于激光沉積制造TA15鈦合金,因?yàn)棣?β相區(qū)溫度較大,首先在α+β相區(qū)進(jìn)行多組不同溫度梯度的退火處理實(shí)驗(yàn),研究在α+β相區(qū)不同退火溫度對(duì)顯微組織以及室溫拉伸力學(xué)性能的影響,并在顯微組織較均勻以及力學(xué)性能較好的溫度區(qū)間內(nèi)進(jìn)一步細(xì)化熱處理溫度;其次在α+β相區(qū)和β相區(qū)進(jìn)行雙重退火實(shí)驗(yàn),研究雙重退火對(duì)顯微組織以及力學(xué)性能各向異性的影響。對(duì)于激光沉積修復(fù)TA15鈦合金,在熱處理時(shí)要保證基體組織的穩(wěn)定性,因此主要考察不同修復(fù)方式下熱處理對(duì)顯微組織組織和力學(xué)性能的影響;而對(duì)于特殊的激光沉積修復(fù)-激光復(fù)合制造來說,由于激光復(fù)合制造涉及鍛造等傳統(tǒng)制造和激光沉積制造兩部分,因此組織上出現(xiàn)較大差異,因此采用β相區(qū)淬火處理+循環(huán)熱處理+退火處理對(duì)激光復(fù)合制造的顯微組織進(jìn)行調(diào)節(jié)和均勻化。通過觀察發(fā)現(xiàn),α相受力變形機(jī)制與α相的形貌、含量和所處的位置有關(guān)。不同的熱處理溫度以及熱處理方式得到的α相形貌不同,不同形貌尺寸和位置的α相具有不同的受力變形機(jī)制,網(wǎng)籃狀α相、片層狀α相以及α團(tuán)束受力變形機(jī)制均不相同,柱狀晶晶內(nèi)α相和柱狀晶晶界兩側(cè)α相的受力變形機(jī)制存在差異。激光沉積修復(fù)TA15鈦合金基材、熱影響區(qū)以及修復(fù)區(qū)的組織不同,造成出現(xiàn)不同的受力變形機(jī)制。β相區(qū)淬火處理+循環(huán)熱處理+退火處理能夠減小激光復(fù)合制造TA15鈦合金沉積部分和基體部分的組織差異性,組織整體上趨近于一致。
[Abstract]:Based on the idea of "discrete stacking", laser deposition technology uses coaxial powder feeding and laser cladding digital forming to further control the forming accuracy of workpiece. However, due to the high density energy accumulation of laser and the singularity of heat dissipation direction in the forming process, the microstructure distribution of the formed parts is not uniform. The mechanical properties are anisotropic. The heat treatment process has the functions of adjusting microstructure and improving mechanical properties. Therefore, the heat treatment process is applied to laser deposition to make forming parts. Because of the particularity of laser deposition manufacturing technology, As a result, the microstructure of the process is obviously different from that of the traditional forging or casting methods, and the heat treatment process needs to be rediscovered and developed. The laser deposition manufacturing technology includes laser deposition manufacturing and laser deposition repair. For laser deposition of TA15 titanium alloy, because the temperature of 偽 尾 phase region is large, the annealing experiments with different temperature gradient are carried out in the 偽 尾 phase region. The effect of annealing temperature in 偽 尾 phase region on the microstructure and tensile mechanical properties at room temperature was studied, and the heat treatment temperature was further refined in the temperature range where the microstructure was uniform and the mechanical properties were better. Secondly, double annealing experiments were carried out in the 偽 尾 and 尾 phase regions to study the effect of double annealing on microstructure and anisotropy of mechanical properties. For laser deposition and repair of TA15 titanium alloy, the stability of matrix structure should be guaranteed during heat treatment. Therefore, the effects of heat treatment on microstructure and mechanical properties under different repair methods are mainly investigated, while for special laser deposition repair and laser composite manufacturing, Because laser composite manufacturing involves traditional manufacturing such as forging and laser deposition, there is a great difference in structure. Therefore, the microstructure of laser composite was adjusted and homogenized by the treatment of 尾 phase quenching and cyclic heat treatment and annealing. It was found that the mechanical deformation mechanism of 偽 phase and the morphology of 偽 phase were observed. The content of 偽 phase is related to the location of the phase. The morphology of 偽 phase is different with different heat treatment temperature and heat treatment method. The deformation mechanism of 偽 phase with different morphologies and positions is different. The deformation mechanism of lamellar 偽 phase and 偽 cluster beam is different, and the deformation mechanism of 偽 phase in columnar crystal is different from that of 偽 phase on both sides of columnar grain boundary. Laser deposition is used to repair TA15 titanium alloy substrate. The microstructure of the heat-affected zone and the repair zone are different, resulting in different deformation mechanisms. The microstructure difference between the deposition part and the matrix part of the TA15 alloy can be reduced by the cyclic heat treatment and annealing treatment in the 尾 phase region, which can reduce the microstructure difference between the deposited part and the matrix part of the TA15 titanium alloy fabricated by laser. The organization as a whole is in line.
【學(xué)位授予單位】：沈陽航空航天大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG665;TG166.5

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