The adiabatic correction factor for deformation heating during the uniaxial compression test
The adiabatic correction factor for deformation heating during the uniaxial compression test
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DOI：
10.1361/105994901770344593
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发表时间：
2001-12-01
影响因子：
2.3
通讯作者：
Semiatin, SL
中科院分区：
文献类型：
--
作者：
Goetz, RL;Semiatin, SL
等温单轴压缩试验是测定金属材料流变应力的常用方法。为了获得应变速率> 10（-3）s（-1）时的精确流变应力数据，必须对变形加热引起的软化进行修正。校正的第一步是确定温度的升高。绝热校正因子η用于确定应变速率为10（-3）至10（1）s（-1）之间的温度。绝热校正因子是在热损失到模具之后保留在工件中的绝热热的分数，eta =（Δ T（实际））/（Δ T（ADIABATIC）），其中Δ T（ADIABATIC）=（0.95积分σ Δ）/（pC（p））。η通常被认为是应变常数，并且在10（-3）和10（1）s（-1）之间随log（λ）线性变化（0到1）。然而，使用有限元法（FEM）和一维，集总参数法，η已被发现随应变，模具和工件的导热系数，和界面传热系数（HTC）。利用集总参数法，推导出了η的解析表达式。在该表达式中，η是模具和工件导热系数、界面传热系数、工件热容、应变和应变速率的函数。结果表明，HTC或热导率的增加降低了η。
The isothermal uniaxial compression test is a common method to determine the flow stress of metals. For accurate flow stress data at strain rates > 10(-3) s(-1), the data must be corrected for now softening due to deformation heating. The first step in the correction is to determine the increase in temperature. An adiabatic correction factor, eta, is used to determine the temperature between strain rates of 10(-3) to 10(1) s(-1). The adiabatic correction factor is the fraction of adiabatic heat retained in the workpiece after heat loss to the dies, eta = (DeltaT(ACTUAL))/(DeltaT(ADIABATIC)) where DeltaT(ADIABATIC) = (0.95 integral sigmad epsilon)/(pC(p)). The term eta is typically taken to be constant with strain and to vary linearly (0 to 1) with log (epsilon) between 10(-3) and 10(1) s(-1). However, using the finite element method (FEM) and a one-dimensional, lumped parameter method, eta has been found to vary with strain, die and workpiece thermal conductivities, and the interface heat-transfer coefficient (HTC). Using the lumped parameter method, an analytical expression for eta was derived. In this expression, eta is a function of the die and workpiece thermal conductivities, the interface heat-transfer coefficient, workpiece heat capacity, strain, and strain rate. The results show that an increase in the HTC or thermal conductivity decreases eta.