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室温下对铝1100及铝合金5754板材进行低速拉伸试验,在此基础上,比较了横梁位移控制和引伸计应变速率控制两种产品性能的测试方法.结果显示,它们具有不同的应变率敏感性;两种拉伸方法并没有对性能产生较大影响;在实际生产检测中可适当提高拉伸速率,并根据检测设备灵活选择控制方式,提高检测效率. 相似文献
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通过对6005A-T6铝合金进行准静态拉伸试验和动态拉伸试验,研究了应变速率对6005A-T6铝合金准静态和动态力学性能及断裂行为的影响。6005A-T6铝合金的强度随着应变速率提高而增大,应变速率200/s拉伸的抗拉强度、屈服强度分别较准静态拉伸提升30MPa、25MPa,其中以准静态到应变速率10/s的过程中,材料的抗拉强度、屈服强度上升最为明显;6005A-T6铝合金塑性随着应变速率的增大而逐渐增大,当应变速率达到200/s时塑性反而下降。在高速拉伸变形状态下,位错密度的增加和滑移带的增多是导致高速状态下强度及延伸率提高的主要原因;当应变速率达到200/s时由于拉伸速率过快,晶粒来不及进行大量变形是断后延伸率反而降低的主要原因。 相似文献
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本文对Hollomon关系式所定义的应变硬化指数(n值)的力学本质,进行了不同拉伸控制模式下的解析,通过单向拉伸实验分析了不同拉伸速率对n值的影响。研究表明:1)应变硬化指数(n值)不是常数,而是与控制模式有关的变量;2)由于多晶体金属材料塑性变形过程的时间性特点,提高拉伸速率会降低n值;3)拉伸在均匀塑性变形阶段推荐使用应变速率控制模式;由于是静载荷拉伸试验,采用较低的拉伸速率使得拉伸各项特征值更接近真实值。 相似文献
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在挂锤式拉伸试验机上对LY12CZ铝合金超塑性应变速率变化规律进行了跟踪观察,发现试验在恒载荷下以最初应变速率变形的时间只有40-60min,随后,应变速率会自动增大,试样断裂时的应变速率比较初始应变速率约高1倍。 相似文献
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高应变速率对挤压态AZ61镁合金力学行为的影响 总被引:1,自引:1,他引:0
采用光学显微镜对挤压态AZ61镁合金的显微组织进行了观察,利用Hopkinson杆杆测试技术对挤压态AZ61镁合金进行了高应变速率冲击拉伸试验,测定了该合金在不同应变速率下的完整动态应力-应变曲线;对该合金在高应变速率下动态应力-应变行为及其应变速率对挤压态AZ61镁合金的屈服行为及其断裂机制的影响进行了分析.结果表明,在整个加载过程中,材料的弹性模量变化很小;在拉伸过程中,该材料表现出明显的屈服点.随着应变速率的增加,材料的抗拉强度相应增大,失稳应变相应减小,但表现出的应变速率强化效应不明显.采用SEM对其断口进行分析,结果表明挤压态AZ61镁合金拉伸断口对应变速率不敏感,表现为以韧性为主伴有少量解理特征的混合断裂. 相似文献
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利用万能试验机、液压伺服高速拉伸试验机和霍普金森杆3种设备,开展了HC340LA低合金高强钢多个应变速率的拉伸试验,得到了不同应变速率下的应力-应变曲线,研究了其动态力学性能。对高速拉伸试验数据进行二次开发,采用SwiftHockett-Sherby本构模型进行拟合外推,建立了HC340LA低合金高强钢的材料模型,并进行了纵梁部件落锤试验过程的数值模拟,数值模拟结果与落锤试验结果基本一致,验证了所建立的材料模型的准确性。同时,对比分析了液压伺服高速拉伸试验机和霍普金森杆设备的高速拉伸试验结果。结果表明:液压伺服高速拉伸试验机测量得到的中低应变速率动态曲线与材料准静态曲线有更好的对应关系;霍普金森杆设备适合更高应变速率的试验,无法精准获取材料的真实变形,只能准确测得材料的抗拉强度。 相似文献
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LIN Junshan YAN Wenbin TU Mingjing Xi''''an Jiaotong University Xi''''an China 《金属学报(英文版)》1992,5(5):379-384
The method to detect the crack initiation point of Charpy pre-cracked specimen under dy-namie loading was studied using strain gauge.The load-time curve and nominal strain-timecurve at the crack tip for impact testing specinens may be shnultaneously measured bytwin-channel oscilloscope with high speed sampling and diskette storing.Based on the dynam-ic finite element simulation of impact response of Charpy specimen,the measuring method ofdynamic fracture toughness was analysed and some problems in previous dynamic fracturetoughness measurement were discussed. 相似文献
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In this paper,a slow bending speed varestraint test method with con-tinuously adjustable deformation rate for testing hot cracking sensitivity is de-veloped and its working principle is described.From great amounts of tests,itis known that strain rate affects the sensitivity of solidification crack because ofits influnce on material ductility in BTR directly.The smaller the strain rate,the better the ductility and the lower the solidification crack sensitivity.The ex-tent of this effect varies with different materials,for LF-6 aluminum alloy,it isgreat,but for 16Mn,19Mn5 and 20G steels,it is small.Through systematicinvestigation,it is concluded that strain rate of a metal during welding can belowered and the resistance to solidification crack can be enhanced by reducingstructrual restraint and by adjustment of welding parameters. 相似文献
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采用电子材料试验机,研究C276高温合金在变形温度650℃~750℃、拉伸速度0.35mm/min~35mm/min条件下的高温拉伸变形行为,分析了变形温度、应变速率对C276合金变形行为的作用及影响规律。结果表明,变形温度和应变速率对合金流变应力有显著影响,流变应力随变形温度升高而降低,随应变速率提高而增大。在变形温度700℃、拉伸速度0.35mm/min和3.5mm/min时,曲线呈现出明显的稳态流变应力特征,合金变形机制以动态回复为主;在变形温度750℃时,随着应变量的增加,合金内发生动态再结晶。利用Zener-Hollomon参数建立了C276合金的变形抗力模型,求得变形激活能为327.66kJ/mol。为C276合金的热加工工艺制定,提供了理论和试验的依据。 相似文献
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CONSTITUTIVERELATIONSHIPOFSUPERALLOYIN718J.M.Zhang;L.Z.Ma;J.Y.Zhuang;Q.Deng;J.HDuandZ.YZhong(DepartmentofSuperalloys,CentralI... 相似文献
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为了探讨C5191磷青铜在高应变速率条件下的动态响应,解决高速冲压工艺问题,本文利用电子万能试验机和分离式Hopkinson拉杆装置对C5191磷青铜分别进行应变速率为0.001S-1和500S-1、1000S-1、1500S-1的准静态和动态拉伸试验,结合SEM和TEM等手段,研究了C5191磷青铜的动态拉伸性能及其变形机制。结果表明:C5191磷青铜高应变速率动态拉伸与准静态条件相比较,其屈服强度和抗拉强度分别提升了32.77%和11.07%;应变硬化指数由0.075增加到0.251;材料强度应变速率敏感指数由0.005变化到0.022,呈现出明显的应变速率敏感性;高应变速率动态拉伸过程中,位错运动速度加快,导致位错“近程阻力”加大,使C5191磷青铜的变形抗力随着应变速率的增加而增大。可动位错数量的显著增多,多系滑移的开启,以及绝热温升软化效应一定程度上提高了C5191磷青铜高应变速率动态拉伸时的塑性。 相似文献
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Comparative survey of classical and strain-induced stress corrosion cracking in connection with case histories involving aluminium and titanium base material The SCC-behaviour of three Al-alloys (2014-T6, 2024-T4, 7075-T6) have been investigated with different conventional testing techniques and the constant strain rate testing technique. The disagreements of the results are explained with the occurrence of pitting. At the Al-alloy AlZnMg 2 is shown that the results as well of the classical as of the constant strain rate testing technique are in good agreement. The SCC-susceptibility of this material is only a function of the stress and not of the strain rate. At two titanium-materials in 3.5% NaCl (Ti6 Al4 V and unalloyed titanium) is shown that the SCC-behaviour is controlled by the strain rate. 相似文献
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W. Schwenk 《工业材料与腐蚀》1978,29(11):740-746
Practical importance of low-cycle loads in connection with strain-induced stress corrosion cracking New investigations on stress corrosion cracking have shown that besides stresses the strain rates are essential factors. In general, stress corrosion cracking occurs within critical ranges of strain rate only. From practical point of view, stress corrosion cracking can be divided into two modes with respect to the lower limiting value of strain rate: classical and non-classical mode. In the first case this value is ≤ 0. Thus, stress corrosion cracking occurs at constant load. In the second case the value is > 0. Thus, stress corrosion cracking can only occur within periods of increasing stresses. Theoretical considerations are in keeping with testing results and show that these conditions exist when slow cycle and low amplitudes are present. Aspects to differentiate between stress corrosion cracking and corrosion fatigue are discussed. 相似文献