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基于ABAQUS软件,采用有限元模拟计算的方法对A357铝合金大型复杂薄壁构件的淬火过程进行研究。通过采用传统的反传热方法,对不同淬火介质在不同温度下的换热系数进行精确求解。精确的换热系数确保对A357铝合金大型复杂薄壁构件淬火过程中温度场预测的准确性。采用3种淬火介质(水、机油,5%-UCON淬火试剂A)。通过综合考虑淬火介质及温度因素,对薄壁构件的残余应力及变形的分布和大小进行有限元预测,得到构件淬火结束后的最大残余应力及变形。 相似文献
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M. Araghchi H. Mansouri R. Vafaei Y. Guo 《Journal of Materials Engineering and Performance》2018,27(7):3234-3238
Residual stresses induced during quenching of aluminum alloys cause dimensional instability and distortion. In this study, the effects of different concentrations of polyalkylene glycol (PAG) quenchants on residual stresses and mechanical properties of 2024 aluminum alloy were investigated. Surface residual stresses were measured by using hole-drilling strain-gauge method. Also, mechanical properties and microstructure of the heat-treated samples were analyzed using hardness measurements, tensile tests, and transmission electron microscopy. Results showed that quenching into a 15% polymeric solution and aging at 190 °C for 12 h cause 50% reduction in residual stress as compared with quenching in water at 20 °C and naturally aging. Moreover, tensile strength decreased by 104 MPa (~?20%) in compared with the T6 sample. 相似文献
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Bowang Xiao Gang Wang Qigui Wang Mohammed Maniruzzaman Richard D. Sisson Yiming Rong 《Journal of Materials Engineering and Performance》2011,20(7):1264-1270
Cast aluminum alloys are usually subject to solution treatment, quenching, and aging hardening for improved mechanical properties.
Cooling rate during quenching plays an important role in residual stress, distortion, and mechanical property distributions
in the resultant cast aluminum components. As the cooling rates of work pieces heavily depend on the interfacial heat transfer
coefficient (HTC) between work pieces and quenchants, it is important to understand how HTC varies with different quenching
conditions so that optimal quenching process can be achieved. In this study, a quenching system and an experimental procedure
of obtaining HTC are presented. A series of experiments have been conducted to study the variations of HTC with respect to
air temperature, air humidity, air velocity, and part orientation. 相似文献
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The cooling curves of 6061 aluminum alloy were acquired through water quenching experiment. The heat transfer coefficient was accurately calculated based on the cooling curves and the law of cooling. The online quenching process of complex cross-section profile was dynamically simulated by the ABAQUS software. The results suggest that the heat transfer coefficient changes during online quenching process. Different parts of the profile have different cooling velocity, and it was verified by water quenching experiment. The maximum residual stress of the profile was predicted using FEM simulation based on ABAQUS software. The relations between the temperature and stress were presented by analyzing the data of key points. 相似文献
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大尺寸6056铝合金薄板经过搅拌摩擦焊接实验后出现了严重的面外变形,虽然变形程度小于熔化焊结果, 但已经影响到被焊薄 板的装配和使用.为详细研究和预测铝合金薄板在搅拌摩擦焊后的残余变形, 以焊接实验条件为基础, 建立了搅拌摩擦焊接三维有限元 热力耦合分析模型. 模型中涉及了利用搅拌头工作转矩计算热输入量、工件和卡具之间的接触热传导、随温度变化的材料模型, 以及综合 考虑搅拌头机械作用等工作.利用该模型可以得到不对称的纵向残余应力结果, 残余变形的趋势在整块板上都与实验结果相同, 而且变形量和实验测量值之间的误差在20%以内. 相似文献
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Evaluation of residual stress relief of aluminum alloy 7050 by using crack compliance method 总被引:3,自引:0,他引:3
1 INTRODUCTION70 5 0alloyisoneofhighstrengthaluminumal loysusedmainlyas platesandforgingsintheaerospaceindustry .Itshighstrengthisachievedthrough quenchingandageing .Duringtherapidquenchingoperation ,highresidualstressesdevelopduetoseverethermalgradient .Theseinternalstress escanleadtodistortionduringsubsequentmachiningoperations ,andincreasethepossibilityofstresscor rosioncracks(SCC) .Residualstressmaybereducedwiththedecreaseofthecoolingratebyapplyingboil ingwaterororganicquenchants .H… 相似文献
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2A12铝合金经固溶时效处理后综合应力的问题一直是制约生产加工的"瓶颈"。对2A12铝合金采取PAG介质淬火,分析其冷却速率对2A12铝合金残余应力、显微组织、常规机械性能、微塑性变形抗力及尺寸稳定性的影响。结果表明,PAG介质处理后2A12合金的残余应力明显降低,提高了铝合金零部件加工的尺寸稳定性。 相似文献
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通过固溶时效工艺可以显著提升2219铝合金的力学性能,但在淬火过程中会产生较大的残余应力,对其尺寸稳定性、疲劳强度、应力腐蚀等性能产生不利影响。为降低2219铝合金环件的淬火残余应力,在淬火和人工时效之间引入冷胀形工艺。首先,采用有限元法模拟分析了2219铝合金环淬火、冷胀形后残余应力的数值及分布规律。其次,采用钻孔法测量了环在淬火、人工时效和固溶-冷胀形-人工时效后的残余应力。研究了冷胀形工艺参数对残余应力数值和均匀性的影响。结果表明,引入冷胀形工艺可以使2219铝合金环件淬火残余应力降低85%以上。 相似文献
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A. Irretier O. Kessler F. Hoffmann P. Mayr 《Journal of Materials Engineering and Performance》2004,13(5):530-536
When precipitation-hardenable aluminum parts are water quenched, distortion occurs due to thermal stresses. Thereby, a costly
reworking is necessary, and for this reason polymer quenchants are often used to reduce distortion, with the disadvantage
that the quenched parts have to be cleaned after quenching. In opposition to liquid quenchants, gas quenching may decrease
distortion due to the better temperature uniformity during quenching. Furthermore, cleaning of the quenched parts can be avoided
because it is a dry process. For this purpose, a heat-treating process was evaluated that included a high-pressure gasquenching
step. Gas quenching was applied to different aluminum alloys (i.e., 2024, 6013, 7075, and A357.0), and tensile tests have
been carried out to determine the mechanical properties after solution annealing, gas quenching, and aging. Besides high-pressure
gas quenching, alloy 2024 was quenched at ambient pressure in a gas nozzle field. The high velocity at the gas outlet leads
to an accelerated cooling of the aluminum alloy in this case. Aluminum castings and forgings can be classified as an interesting
field of application of these quenching methods due to their near-net shape before the heat treatment. Cost savings would
be possible due to the reduced distortion, and therefore, less reworking after the precipitation hardening. 相似文献
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Residual stress in quenched 7075 aluminum alloy thick plates 总被引:3,自引:0,他引:3
1 INTRODUCTION70 75isoneoftheprecipitation hardenedalu minumalloysmainlyusedasplateandforgingsintheaerospaceindustry .Itshighstrengthisachievedthroughaquenchingoperationwherethematerialisrapidlycooledfromthesolutionheattreatmenttem perature(4 75℃ )toroomtemperature ,whichcancausetheadverseeffectofintroducingresidualstress ,leavingthematerialunsuitableforfurthermachiningoperationsandforservice[13] .Residualstressinthequenchingoperationforaluminumalloysisusuallystudiedbynumericalprediction… 相似文献
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《中国有色金属学会会刊》2020,30(5):1211-1226
The interfacial heat transfer coefficient between hot profile surface and cooling water was determined by using inverse heat conduction model combined with end quenching experiment. Then, a Deform-3D thermo-mechanical coupling model for simulating the on-line water quenching of extruded profile with unequal and large thicknesses was developed. The temperature field, residual stress field and distortion of profile during quenching were investigated systematically. The results show that heat transfer coefficient increases as water flow rate increases. The peak heat transfer coefficient with higher water flow rates appears at lower interface temperatures. The temperature distribution across the cross-section of profile during quenching is severe nonuniform and the maximum temperature difference is 300 °C at quenching time of 3.49 s. The temperature difference through the thickness of different parts of profile first increases sharply to a maximum value, and then gradually decreases. The temperature gradient increases obviously with the increase of thickness of parts. After quenching, there exist large residual stresses on the inner side of joints of profile and the two ends of part with thickness of 10 mm. The profile presents a twisting-type distortion across the cross-section under non-uniform cooling and the maximum twisting angle during quenching is 2.78°. 相似文献
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针对铝合金焊接接头的软化问题,通过采用合理材料模型对该问题进行了描述,并在此基础上开发了相应的热-弹-塑性有限元计算方法来预测铝合金薄板的焊接变形和残余应力.以TIG重熔铝合金薄板为例,模拟分析了焊接过程中的温度场、残余应力和焊接变形.同时,采用试验方法测量了焊件的挠曲变形.结果表明,考虑软化现象的有限元数值计算结果与试验测量结果更吻合,验证了提出材料模型和所开发的有限元计算方法的有效性;对于接头软化较为明显的铝合金材料,进行焊接残余应力的数值模拟时有必要建立反映接头软化的材料模型. 相似文献
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Al-Zn-Mg-Cu系铝合金属于时效强化合金,主要靠析出硬化来提高强度.以Al-Zn-Mg-Cu系中的7039铝合金为实验材料,进行析出硬化热处理研究.采用T4、T6、T73、T76等4种不同的热处理工艺条件与4种不同的淬火方式(冷水、沸水、热油、鼓风)分别进行实验,并对每组工艺参数处理下的试片进行硬度测量,找出最佳的热处理工艺参数.研究结果表明:采用T73的时效处理可得到较高的硬度值,淬火方式对铝合金的硬度影响较小,但鼓风淬火明显低于其它三种方式.由于固溶处理后合金表面处在压应力状态内部处在拉应力状态,因此应采用较为缓和的淬火方式,如沸水淬火和热油淬火,以减小工件的内应力. 相似文献
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为探究淬火残余应力对铝合金厚板疲劳裂纹扩展的影响规律,建立7075铝合金厚板表面三维裂纹数值仿真模型。采用顺序热力耦合法求解淬火残余应力场,将残余应力场作为初始载荷条件求解裂纹应力强度因子,并与无残余应力场的应力强度因子值进行对比,研究两种条件下应力强度因子的分布规律和两者之间的异同;通过分析在初始淬火残余应力条件下不同半径裂纹受不同均匀拉应力荷载作用时的裂纹应力强度因子随裂纹位置角的演变曲线,探究淬火残余应力对裂纹扩展趋势的影响规律。结果表明,淬火残余应力的存在改变了铝合金厚板应力强度因子的分布规律和裂纹的扩展趋势,淬火残余应力使表层附近的裂纹扩展受到遏止,裂纹易于在厚度方向优先扩展。 相似文献
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Finite Element Analysis of Residual Stress and Distortion in an Eccentric Ring Induced by Quenching 总被引:1,自引:0,他引:1
LI M. Victor 《材料热处理学报》2004,25(5)
THERE is a pressing need in the metal manufacturingindustries to minimize the amount of rework due tosuch unanticipated effects of quenching as distortionand cracking.Computational modeling offers apowerful tool to predict the component response toquenching.However,physics associated with thequenching process and materials response is verycomplex.There is not yet a complete set of modelsthat can fully incorporate all the relating factorstogether and readily duplicate the experimentalresults.… 相似文献
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D.D Hall I Mudawar R.E Morgan S.L Ehlers 《Journal of Materials Engineering and Performance》1997,6(1):77-92
Optimal cooling of aluminum alloys following the high- temperature extrusion process suppresses precipitation of intermetallic
compounds and results in a part capable of possessing maximum strength and hardness after the subsequent age- hardening process.
Rapid quenching suppresses precipitation but can lead to large spatial temperature gradients in complex- shaped parts, causing
distortion, cracking, high residual stress, and/or nonuniform mechanical properties. Conversely, slow cooling significantly
reduces or eliminates these undesirable conditions but allows considerable precipitation, resulting in low strength, soft
spots, and/or low corrosion resistance. This study presents a systematic method of locating and operating multiple spray nozzles
for any shaped extrusion such that uniform, rapid cooling and superior mechanical and metallurgical properties are achieved.
A spray nozzle data base was compiled by measuring the distribution of spray hydrodynamic parameters (volumetric spray flux,
mean drop diameter, and mean drop velocity) throughout the spray field of various industrial nozzles. Spray heat transfer
correlations, which link the local spray hydrodynamic parameters to the heat transfer rate in each of the boiling regimes
experienced by the surface, defined the spatially nonuniform boundary conditions in a numerical model of the quenching process
that also accounted for interference between adjacent spray fields. New correlations, offering increased accuracy and less
computational time, were formulated for the high- temperature boiling regimes which have a critical influence on final mechanical
properties. The quench factor technique related predicted thermal history to metallurgical transformations occurring within
the extrusion to predict hardness distribution. The validity of this unique approach was demonstrated by comparing model predictions
to the temperature response (and hardness after artificial aging) of an L- shaped Al 2024- T6 extrusion to quenches with multiple,
overlapping water sprays. The validation study reported herein concludes by exploring the possibility of applying quenching
technology to improving the properties of extruded metal- matrix composites such as SiCp/Al 6061 and cast alloys. 相似文献