發(fā)布時間：2018-04-13 02:28

  本文選題：激光沉積修復(fù) + GH4169合金��； 參考：《沈陽航空航天大學(xué)》2017年碩士論文

【摘要】：GH4169高溫合金由于其在高溫環(huán)境下具有優(yōu)良的綜合使用性能,廣泛應(yīng)用于航空航天、核能、石油化工及其他領(lǐng)域,尤其在航空航天領(lǐng)域存在大量高溫合金制造的大型薄壁零件。這些零部件在機(jī)械加工過程中不可避免地會產(chǎn)生如尺寸超差、銑切溝槽等誤加工損傷,且在服役使用過程中也會產(chǎn)生裂紋、腐蝕和磨損等損傷。本文主要針對表面損傷試樣,開展了激光沉積修復(fù)工藝研究,重點研究了GH4169合金激光修復(fù)、預(yù)熱下激光修復(fù)、熱處理等的顯微組織特征、拉伸性能、拉伸斷口等內(nèi)容。研究主要成果如下:針對GH4169合金薄壁零部件表面損傷修復(fù)研究問題,開展了不同厚度基體的激光沉積修復(fù)試驗研究,研究并分析了修復(fù)件的殘余應(yīng)力、微觀組織及室溫拉伸性能的變化規(guī)律。研究發(fā)現(xiàn),基體厚度越小,殘余應(yīng)力增加,枝晶間析出的Laves相體積分?jǐn)?shù)變大,拉伸性能降低�？梢娀w厚度對表面損傷修復(fù)試樣的拉伸性能及顯微組織影響顯著。針對GH4169合金表面損傷修復(fù)試樣性能弱化問題,開展了不同基體厚度的預(yù)熱修復(fù)研究,研究了基體預(yù)熱對殘余應(yīng)力、顯微組織及拉伸性能等的影響規(guī)律。試驗表明:當(dāng)基體預(yù)熱至300°C時,其殘余應(yīng)力均明顯降低,Laves相變得粗壯并呈現(xiàn)出顆粒狀的碎化趨勢,抗拉強(qiáng)度略微降低,但斷后伸長率提高了60%以上。試驗表明基體預(yù)熱有利于提高激光沉積修復(fù)GH4169合金的塑性。針對激光沉積修復(fù)GH4169合金過程中存在較大殘余應(yīng)力問題,開展了低能量輸入激光沉積修復(fù)GH4169合金試驗研究。試驗表明,采用600w低能量輸入進(jìn)行損傷試樣的激光沉積修復(fù),修復(fù)試樣的殘余應(yīng)力較1400w高能量輸入小,可獲得較小熱影響區(qū)。針對激光沉積修復(fù)工件的力學(xué)性能下降問題,開展了局部熱處理和真空熱處理的試驗研究。研究發(fā)現(xiàn),經(jīng)熱處理后,局部熱處理試樣修復(fù)區(qū)平均硬度增加,真空熱處理試樣修復(fù)區(qū)平均硬度也增加,略高于局部熱處理。兩種熱處理方式下拉伸斷口的韌窩尺寸較沉積態(tài)變化不大。試驗表明局部熱處理和真空熱處理都可達(dá)到提高拉伸性能的目的。
[Abstract]:GH4169 superalloys are widely used in aerospace, nuclear energy, petrochemical and other fields because of their excellent comprehensive performance in high temperature environment. Especially in aerospace, there are a large number of large thin-walled parts made of superalloys.In the process of machining these parts will inevitably produce damage such as dimension oversize milling grooves and so on. Also cracks corrosion and wear will occur in the course of service and use.In this paper, the laser deposition and repair technology for surface damage samples was studied, and the microstructure, tensile properties and tensile fracture of GH4169 alloy were studied in detail, such as laser repair, laser repair under preheating, heat treatment and so on.The main results are as follows: aiming at the problem of surface damage repair of thin wall parts of GH4169 alloy, the laser deposition repair experiments of different thickness matrix are carried out, and the residual stress of the repair parts is studied and analyzed.Changes of microstructure and tensile properties at room temperature.It is found that the smaller the matrix thickness, the greater the residual stress, the larger the volume fraction of the Laves phase precipitated between dendrites, and the lower the tensile properties.The effect of matrix thickness on the tensile properties and microstructure of surface damage repair specimens is obvious.Aiming at the problem of weakening the properties of GH4169 alloy surface damage repair specimen, the preheating repair of different matrix thickness was carried out, and the influence of matrix preheating on residual stress, microstructure and tensile properties was studied.The experimental results show that the residual stress of Laves phase decreases obviously when the matrix is preheated to 300 擄C, and shows a tendency of granular fragmentation, and the tensile strength decreases slightly, but the elongation increases by more than 60% after breaking.The results show that the preheating of the substrate is beneficial to improve the plasticity of the GH4169 alloy by laser deposition.Aiming at the problem of residual stress in the process of laser deposition and repairing of GH4169 alloy, the experimental study of low energy input laser deposition for repairing GH4169 alloy was carried out.The experimental results show that the residual stress of the damaged specimen is smaller than that of the high energy input of 1400w, and a smaller heat affected zone can be obtained by using 600w low energy input to repair the damaged sample by laser deposition.Aiming at the degradation of mechanical properties of workpiece repaired by laser deposition, the experimental study of local heat treatment and vacuum heat treatment was carried out.It is found that after heat treatment, the average hardness of the repair zone of the local heat treatment specimen increases, and the average hardness of the vacuum heat treatment sample area increases, which is slightly higher than that of the local heat treatment.The dimple size of tensile fracture has little change compared with that of deposition under two kinds of heat treatment.The results show that both local heat treatment and vacuum heat treatment can improve the tensile properties.
【學(xué)位授予單位】：沈陽航空航天大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG132.3;TG665

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本文編號：1742546