Effect of Sample Geometry on Strain Uniformity and Double Hit Compression Tests for Softening Kinetics Determination
Effect of Sample Geometry on Strain Uniformity and Double Hit Compression Tests for Softening Kinetics Determination
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DOI：
10.1002/srin.202200157
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发表时间：
2022-08-18
影响因子：
2.2
通讯作者：
Davis，Claire
中科院分区：
文献类型：
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作者：
Tamanna，Nusrat;Slater，Carl;Davis，Claire
静态软化是钢材热轧过程中细化晶粒、提高力学性能的重要过程。采用双击试验从流变应力曲线上测量静态软化体积分数。在此，不同的样品几何形状对从预期0-99%软化的条件下的双击试验确定软化分数的影响。在单轴压缩和标准平面应变压缩试验中，在DEFORM中对常规样品几何形状进行了双击试验建模，并对设计用于提供更均匀应变分布的改良平面应变压缩试验样品几何形状进行了额外模拟。一个用户例程被纳入到模型中，以预测局部软化体积分数从局部应变的基础上已知的软化方程和设置回局部应变值为零，而软化体积分数达到85%。标准的平面应变压缩试验的几何形状示出了一个强大的应变梯度，导致不准确的软化分数体积预测从流动应力，而单轴压缩试验和修改后的平面应变压缩试验的几何形状显示更好的预测软化体积分数从流动应力数据。
Static softening is an essential process during the hot rolling of steel to refine grain size and improve mechanical properties. The double hit test is used to measure the static softening volume fraction from the flow stress curves. Herein, the influence of different sample geometries on the determination of softening fraction from the double hit test for conditions where 0–99% softening is expected. The double hit tests are modeled in DEFORM for conventional sample geometries in both uniaxial compression and standard plane strain compression tests, and an additional simulation of a modified plane strain compression test sample geometry, designed to provide more uniform strain distributions, is also performed. A user routine is incorporated into the model to predict the localized softening volume fraction from localized strain based on known softening equations and set back the localized strain value to zero while the softening volume fraction reaches 85%. The standard plane strain compression test geometry shows a strong strain gradient resulting in inaccurate softening fraction volume predictions from flow stress, whereas the uniaxial compression test and modified plane strain compression test geometries show better predictions of softening volume fraction from the flow stress data.