NUMERICAL SIMULATION STUDY ON DEFORMATION UNIFORMITY OF EQUAL CROSS SECTION LATERAL EXTRUSION

Equal cross section lateral extrusion (ECSLE) is an effective method realizing pure shear deformation.The influence of friction factor on the deformation uniformity of ECSLE was investigated with rigid plastic finite element method.The result shows that the non-uniform deformation in extrusion is caused mainly by the friction between workpiece and die.The higher the friction factor is.the more uneven plastic deformation resulted in extruded workpiece.The relation curve of deformation uniformity vs. friction factor was drawn based on the analysis result. The curve can be used as a basis of ECSLE process design.     

升温率和应变率对30CrMnSi拉伸强度的影响

报道了硬度ＨＲＣ为２０和４０的两种３０ＣｒＭｎＳｉ材料在１００－９００℃的力学性能及升温率，应变率和热处理条件对抗拉强度，屈服强度的影响。在低温区，材料性能随温度的升高，呈现缓慢下降，其数值与常温相差不多，热处理状态对该区影响甚大，升温率有一定影响；在高温区，材料强度大大降低，其数值随温度变化不大，不同升温速率的影响及热处理状态影响消失；在中温区，材料性能随温度升高呈现快速下降趋势，热处理状态对材     

TiNi和TiNiCu记忆合金可逆应变能与温度的经验关系

在实验基础上研究了Ti_(50)Ni_(50),Ti_(50)Ni_(45)Cu_2)和Ti_(50)Ni_(45)Cu_5的可逆形状记忆效应,得到可逆应变能U_r与温度的经验关系: U_r=U_0[1-exp(-mT_R~N)] 式中,n是形状一温度敏感指数,m是与材料特性有关的常数.移植Johnson-Mehl-Avrami描述相变-时间关系的唯象方法,得到与可逆形状记忆效应相伴随的热弹性马氏体相变与温度的半定量关系,且与上述经验关系对应.     

深冲汽车簿钢板织构的表述方法

利用晶体学性质,将深冲汽车薄板的两种主要特征织构表述于反极图之中,再利用织构定量技术便能简捷地分析深冲钢板的织构与深冲性能的关系。经验证,此法与ODF定量分析所得的结果一致。     

Bi2223超导带材的机械性能的改善

通过在超导芯部引入Ag合金的方法制备了新结构单芯和多芯带材，并研究了此种带材机械性能，以及其相对于普通Bi-2223超导带材变化。这种新结构提高了Bi-2223超导带材抗拉伸应变的能力。在拉伸应力的作用下，单芯样品的屈服强度和σ0.2不可逆应变极限εirr和普通样品相比均有较大幅度的提高，其中的最大不可逆应变极限εirr约为0．32％，最大屈服强度σ0.2约为85MPa。多芯样品的最大不可逆应变极限εirr约为1．1％，最大屈服强度σ0.2约为160MPa。实验证明添加合金丝提高了纯银包套多芯带材的不可逆应变极限εirr，并减弱了临界电流的退化速度。但对合金包套的带材影响不大，这时合金包套对于带材的力学性能起主要作用。     

厚向异性板应力应变强度表述方法讨论

从希尔 (Hill)正交各向异性体二次屈服函数出发 ,可以导出厚向异性板应力强度 (等效应力 )与应变强度 (等效应变 )的两组表达式 ;本文讨论了采用两组不同表述方法的选择 ,并利用单向拉伸与双向等拉两种实验作了可比性的分析比较     

Analysis of damage localization for ductile metal in process of shear band propagation

1 Introduction Shear localization is an important and often dominating deformation and failure mechanism for Ti and Ti alloy in dynamic loadings[1—10]. The eventual outcome of localized deformation is ductile rupture and material separation. Shear locali…     

Effect of temperature on mechanical behavior of AZ31 magnesium alloy

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.     

DD3单晶镍基合金蠕变—疲劳及寿命预测

从应变范围区分法(SRP),应变能区分法(SEP)的有关概念出发,研究DD3单晶镍基合金拉—拉应力状态下的蠕变—疲劳性能和保持时间的影响,并对其进行了定量计算;同时,用应变能区分法的数值法(SEP—NCM)实现对拉—拉应力状态下蠕变—疲劳的寿命预测。     

STRAIN INDUCED STRUCTURAL TRANSITION OF INTERFACES AND TWINS IN A HOT－DEFORMED DUAL－PHASE TIAL ALLOY

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