Optimising compression testing for strain uniformity to facilitate microstructural assessment during recrystallisation
Optimising compression testing for strain uniformity to facilitate microstructural assessment during recrystallisation
复制标题
DOI：
10.1016/j.rinma.2021.100218
复制
发表时间：
2021-09
期刊：
影响因子：
--
通讯作者：
C. Slater;N. Tamanna;C. Davis
中科院分区：
文献类型：
--
作者：
C. Slater;N. Tamanna;C. Davis
预测金属中再结晶的动力学和再结晶的晶粒尺寸分布是在金属加工期间控制和细化晶粒尺寸的关键方法之一，这通常增加强度和韧性/延展性。基于实验室的模拟支持重结晶预测模型和方程，可以系统地评估不同材料和起始晶粒尺寸在一定温度和应变范围内的重结晶。这项工作使用建模和实验验证，以评估不同的常用压缩测试样品的几何形状，以确定应变均匀性和微观结构评估中的潜在误差来源，并提出了一个修改后的几何形状，增加了恒定的已知应变的面积。而所有样品的流动应力测量结果显示出良好的一致性。它已被证明，新的平面应变几何形状提供了一个更一致的，均匀的应变，通过样品，以便大量的晶粒需要准确的粒度分布测量可以很容易地实现。与传统单轴试样相比，改进的平面应变试样达到了目标应变±10%的面积的两倍以上，该面积也被证明更有利于金相评估，并且每个横截面切片提供超过1500个250 μm的晶粒进行评估。
Predicting the kinetics of recrystallisation in metals, and recrystallised grain size distributions, is one the key approaches to controlling and refining grain size during metal processing, which typically increases strength and toughness/ductility. Recrystallisation prediction models and equations are supported by lab-based simulations that can systematically assess recrystallisation over a range of temperatures and strains for different materials and starting grain sizes. This work uses modelling and experimental verification to assess the different commonly used compression test sample geometries to determine strain uniformity and potential sources of error in microstructural assessment and proposes a modified geometry that increases the area of constant known strain. Whilst flow stress measurements in all samples showed good agreement. It has been shown that the new plane strain geometry offers a more consistent, homogeneous strain through the sample such that the large number of grains needed for accurate grain size distribution measurement can be readily achieved. Over double the area of ±10% of the target strain was achieved in the modified plane strain sample compared to a conventional uniaxial specimen, this area was also shown to be more conducive to metallographic assessment and offers in excess of 1500 grains of 250 μm to be assess per cross-sectional slice.