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Strain rate sensitivity and tension/compression asymmetry of AZ31 magnesium alloy at different temperatures and strainrates were investigated.Both of mechanical behaviors are temperature dependent.Strain rate sensitivity increases with increasingtemperature.Thermally activated slip is the source of strain rate sensitivity.At the temperature below or near 373 K,strain ratesensitivity is very little.Tension/compression asymmetry in yielding decreases with increasing temperature.Twinning is the reasonof tension/compression asymmetry.At the temperature above or near 573 K,the material shows little tension/compressionasymmetry of the flow stress. 相似文献
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AZ31镁合金表面液相渗铝的工艺与性能 总被引:5,自引:0,他引:5
采用液相扩渗技术在挤压态AZ31镁合金表面快速渗入铝,在合金表面获得过共晶渗层,并对渗层的成分、相组成、扩渗过程、纳米硬度和腐蚀性能进行分析。结果表明:AZ31镁合金在480℃热扩渗铝过程中发生了“熔化—凝固”变化,渗层为典型的过共晶组织:渗铝层含有Mg17A112相和镁的铝饱和固溶体,这种渗层具有较高的纳米硬度和较好的耐腐蚀性能;通过提高扩渗温度进行液相扩渗可以大大提高扩渗速度,但由于快速凝固收缩会造成表层产生起伏现象,控制冷却速度可以将表层起伏控制在可接受的范围。 相似文献
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绝热剪切带内微孔洞演化规律研究 总被引:2,自引:1,他引:2
为深入了解绝热剪切带内微孔洞的演化规律,进而揭示高应变率加载条件下绝热剪切破坏的特殊规律,本文对D35钢进行了约束爆破实验,爆破后回收圆筒的微观观察表明,绝热剪切破坏要经过绝热剪切带内微孔洞形核、长大和相互联接形成裂纹等一系列演化过程.在Guduru P等人的测试结果和Li Shaofan等人数值仿真结果基础上,通过简化(剪切带内的温度分布为由剪切带中心向边缘线性降低,并最终降至与基体温度相同; 微孔洞的形核、长大受温度控制,长大速度随温度呈指数规律降低)对Timothy S P和Hutchings I M的模型进行了修正,修正后的模型可以定量的描述绝热剪切带内微孔洞的演化直至破坏的全过程,模型的描述与微观分析获得的实验结果有较好的一致性. 相似文献
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采用分离式Hopkinson压杆获得了冲击压缩方向与热轧态A231B镁合金板材法向分别成90°、45°及0°的动态应力一应变曲线,利用光学显微镜及透射电子显微镜对微观组织演化过程进行了分析。结果表明:应变率约为1 200 s-1,压缩方向与板面法向成90°时,孪晶的面积分数随应变量的增大逐渐增加,孪生是主要变形机制,其曲线为凹型;压缩方向与板面法向成45°及0°时,其塑性变形以位错滑移为主,曲线形状分别为近似线型和凸型;应变率约为2 800 s-1,压缩方向与板面法向成90°时,孪晶面积分数迅速增加,大多数晶粒取向发生7改变,有利于滑移,其曲线由较低应变率的凹形变为凸型。 相似文献
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利用Instron 电子拉伸机和分离式霍普金生压杠(SHPB)实验装置, 研究了准静态和动态压缩条件下热轧TB2钛合金织构多晶板的力学性能。对TB2钛合金板材的轧向、横向以及轧制平面内与轧向成45°等3个方向进行了压缩实验, 得到了不同应变速率下的应力-应变曲线。结果表明:热轧TB2钛合金板材不同方向上的流变应力均随应变速率的增加而增加, 表现出明显的应变速率强化效应。准静态和动态力学性能均表现出各向异性, 且准静态和动态压缩行为规律不一致。考虑准静态和动态变形时可能的塑性变形机制, 基于微观晶体塑性变形理论, 定性讨论了热轧织构多晶TB2钛合金板屈服强度的各向异性 相似文献
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利用Instron电子拉伸机和Split-Hopkinson压杆(SHPB)实验装置,研究了准静态和动态压缩条件下冷轧和退火Cu板法向、轧向、横向的力学性能.不同应变率下的应力-应变曲线表明:冷轧和退火Cu板的流变应力均随应变率的增加而增加,表现出明显的应变率强化效应.冷轧Cu板准静态和动态压缩力学性能均呈现明显的各向异性:横向屈服强度最大,轧向最小,且低应变程度下的流变应力也具有同样规律.退火Cu板呈现近似各向同性.考虑准静态和动态变形时可能的塑性变形机制,基于微观晶体塑性变形理论的Taylor模型可定性地解释冷轧Cu板压缩力学性能的各向异性. 相似文献
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The twinning and slip activities of AZ31 magnesium alloy sheet at a strain rate of 1 200 s^-1 were investigated. Dynamically mechanical properties of various oriented samples were measured using Split Hopkinson Pressure Bar(SHPB). Optical microscope observations reveal that the dominant deformation mechanism is twinning for 90° oriented sample, and is slip for 45° and 0° oriented samples. TEM analysis for samples at a strain of 0.3% shows that the main deformation mechanisms for 90°, 45° and 0° oriented sample are {1012} 〈 1011 〉 and {1011} 〈 1012 〉 twinning, basal slip and non basal slip, respectively. The main features of the true stress--true strain curves can be explained based on deformation mechanism analysis. 相似文献
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采用分离式Hopkinson压杆(SHPB)对A231B热轧板材沿轧向进行冲击实验,加载应变率约为1200 s-1.利用金相显微镜和透射电子显微镜观察微观组织特征。结果表明:在应变量约为0.003的条件下,压缩孪生{10?1}/<10?2>与拉伸孪生{1?02}/< 1?01>均为孪生塑性变形机制,这与准静态加载下单一的拉伸孪生机制不同。孪晶内部的微观特征演化过程包括:1)平行排列基面层错的出现;2)与孪晶界成特定角度平行排列位错线的形成;3)位错胞的产生。 相似文献
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The deformation behavior of AZ31 was examined by compression and tension testes over a wide strain rate and temperature range, strain rate from 10^-3 to 10^3 s^-1, temperature from 300 to 623 K. Analysis of flow behavior and microstructural observations indicate that in tension tests dislocation glide is the most important deformation mechanism in the test strain rate and temperature range, while in compression tests twinning deformation mechanism is important at lower temperature when the strain rate ranges from 10^-3 to 10 s^-1. At 10^3 s^-1 strain rate, dislocation glide and twinning are present at the same time. At the strain rate of 2 964 s^-1, adiabatic shear band can be found easily, even at the strain rate of 1 537 s^-1 adiabatic shear localization zone can be found. In adiabatic shear localization zone, there are fine recrystallization grains. But in adiabatic shear band, the grains cannot be identified by optical microscopy. 相似文献