發(fā)布時(shí)間：2018-02-12 21:52

  本文關(guān)鍵詞： 鎳基單晶高溫合金 TLP 壓力 母材液化 組織性能　出處：《南昌航空大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：鎳基單晶高溫合金具有優(yōu)良的高溫力學(xué)性能,是航空發(fā)動(dòng)機(jī)渦輪葉片的主要材料。隨著飛機(jī)渦輪葉片冷卻形式的發(fā)展,空心型腔越來越復(fù)雜,單憑鑄造技術(shù)很難實(shí)現(xiàn)結(jié)構(gòu)復(fù)雜葉片的制造,采用兩半對(duì)開或組合式空心葉片是解決脫芯難題的先進(jìn)方案,其制備過程必然涉及到材料的連接問題。本文采用厚度為20μm的非晶箔狀BNi9作為中間層,對(duì)厚度為10mm的DD407鎳基單晶進(jìn)行TLP連接。研究無壓和壓力作用下工藝參數(shù)對(duì)鎳基單晶TLP連接接頭組織及性能的影響,通過金相組織觀察和能譜測(cè)試,詳細(xì)分析了無壓和壓力作用下接頭形貌及各元素分布。并對(duì)壓力作用下,焊縫中心和焊縫邊緣接頭形貌及焊接溫度和保溫時(shí)間對(duì)接頭組織性能的影響進(jìn)行了分析。通過對(duì)比不同壓力作用下,接頭組織性能及元素?cái)U(kuò)散,進(jìn)一步探索了壓力在TLP中作用機(jī)制。研究結(jié)果表明:無壓作用下,接頭抗拉強(qiáng)度隨著焊接溫度升高先增大后減小,隨著保溫時(shí)間延長(zhǎng)先增大后趨于平緩,當(dāng)焊接溫度為1150℃,保溫時(shí)間為2h時(shí),接頭強(qiáng)度最大為954.1MPa,斷裂發(fā)生在母材中,斷口存在白色的撕裂帶,分析為準(zhǔn)解理斷裂;接頭組織隨著焊接溫度和保溫時(shí)間增大,越來越均勻,當(dāng)焊接溫度為1150℃,保溫時(shí)間4h后,焊縫中心組織完全均勻化,接頭中心元素分布均勻。有壓作用下,接頭抗拉強(qiáng)度隨著壓力的增加而增加,當(dāng)壓力為3MPa時(shí),接頭強(qiáng)度最大為744MPa,斷裂發(fā)生在母材,相對(duì)于無壓下,斷口未見白色的撕裂帶,表現(xiàn)為瞬間拉斷,并且壓力的作用使得母材中強(qiáng)化相γ′發(fā)生嚴(yán)重變形。3MPa作用下,焊縫中心組織均勻,主要為γ、γ′;焊縫邊緣存在殘余共晶區(qū),組織分別為深灰色CrB,淺灰色Ni3B-γ共晶相,基體γ、γ′相;擴(kuò)散區(qū)中近縫顆粒狀組織為(Cr,Mo,W)3B2,遠(yuǎn)離焊縫針狀組織為(Cr,Mo,W)5B3。3MPa作用下,接頭抗拉強(qiáng)度隨著焊接溫度的增加變化不大,最大抗拉強(qiáng)度能達(dá)到776MPa,隨著保溫時(shí)間的增加先增大后減少,最后趨于平緩,當(dāng)保溫時(shí)間為2h時(shí),接頭抗拉強(qiáng)度為744MPa。斷裂均發(fā)生在母材。壓力的作用機(jī)制,起始階段,在壓力的作用下,母材表面和中間層之間凸起的部位被壓平。隨著溫度的升高,中間層首先達(dá)到熔點(diǎn)并迅速熔化,降熔元素B往母材擴(kuò)散,當(dāng)擴(kuò)散量達(dá)到一定值時(shí),母材開始液化。壓力的施加,使得焊縫中心液相被擠壓到焊縫邊緣,從而使得焊縫中心未發(fā)生等溫凝固,原子間進(jìn)行液相擴(kuò)散,使得組織均勻。而焊縫邊緣各元素濃度增大,降熔元素濃度增大對(duì)焊縫邊緣的母材繼續(xù)產(chǎn)生液化,使得焊縫邊緣的寬度更大。焊縫邊緣殘留的液相在冷卻過程中產(chǎn)生共晶。
[Abstract]:Nickel base single crystal superalloy has excellent high-temperature mechanical properties, is the main material of aeroengine turbine blade. With the development of aircraft turbine blade cooling form, the hollow cavity is more and more complex, with casting technology is difficult to achieve the complex structure of blade manufacturing, the two half of open or combined hollow blade is advanced to solve scheme the core problem, its preparation process involves the connection material. This paper uses the thickness of amorphous foil BNi9 20 m as the middle layer with a thickness of DD407 nickel base single crystal 10mm TLP. Study on influence of process parameters on pressure and pressure of nickel base single crystal TLP connection and the performance of joint organization, through the microstructure observation and energy spectrum test, a detailed analysis of the distribution and morphology of joint elements without pressure and pressure. And the pressure, the center of weld and weld seam edge joint. And the welding temperature and holding time on the microstructure and properties of welded joint are analyzed. Through the contrast effect under different pressure, microstructure and mechanical properties of joint element diffusion, to further explore the mechanism of pressure in TLP. The results show that: no pressure, tensile strength of joint with the welding temperature increased first and then decreased with thermal insulation time first increased and then leveled off, when the welding temperature is 1150 DEG C, the holding time is 2h, the joint strength is 954.1MPa, the fracture occurred in the parent metal, there is white with tear fracture analysis to quasi cleavage fracture; microstructure with welding temperature and holding time increasing, more and more uniform, when the welding temperature 1150 C, the holding time after 4h, the weld center organization completely uniform, joint center elements evenly distributed. The pressure under the action of tensile strength increases with increasing pressure, when the pressure is 3M Pa, the joint strength is 744MPa, the fracture occurred at the base metal, with no pressure, no fracture white tear tape, is instantly pulled off, the pressure and the parent material strengthening phase in gamma 'serious deformation under the action of.3MPa, the center of weld microstructure, mainly for gamma, gamma'; the presence of residual eutectic zone of the weld edge, the microstructures are dark grey CrB, light grey Ni3B- gamma eutectic phase, the matrix gamma, gamma prime phase; diffusion region near the joint organization for granular (Cr, Mo, 3B2, W) from acicular tissue (Cr, Mo, W) 5B3.3MPa under the action of joint the tensile strength of welding with the increase of temperature changes little, the maximum tensile strength can reach 776MPa, with the increase of the holding time increases first and then decreases, finally tends to be stable when the holding time is 2h, the tensile strength of 744MPa. fracture occurred in the base metal. The mechanism, the pressure in the initial stage, the effect of pressure Under bump between base material surface and middle layer parts are flattened. With the increase of temperature, the middle layer and the first to reach the melting point rapidly melting, melting pointdepressants B diffusion into the parent material, when the diffusion amount reaches a certain value, the parent material to liquefaction. Pressure, the liquid is extruded to the weld center the edge of the weld, so that the weld center without the occurrence of isothermal solidification, liquid phase diffusion between atoms, the uniform microstructure and weld edge. Each element concentration increases, the increase of the concentration of the parent metal melting pointdepressants on the edge of the weld continues to produce liquefaction, make the weld edge width is greater. The edge of the weld residual liquid generated in eutectic during the cooling process.

【學(xué)位授予單位】：南昌航空大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TG453.9

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