拉伸变形对Hastelloy C-276合金组织与力学性能的影响

Effects of Tensile Deformation on Microstructure and Mechanical Properties of Hastelloy C-276 Alloy

采用金相（OM）、电子背散射衍射（EBSD）以及拉伸实验等技术手段研究了不同变形量条件下Hastelloy C-276合金薄板的组织演化特征和力学性能。结果表明：变形量小于14%时,位错优先在晶界附近塞积,并产生局部应变集中;变形量在14%~30%范围内,孪晶界附近及晶粒内部产生大量位错,位错滑移引起晶粒内部应变集中增强;变形量由0%增加至30%,晶界应变集中程度因子先增大后减小,变形量为14%时晶界应变集中程度因子最大。利用Ludwigson模型回归拟合了不同变形条件下的真应力-真应变曲线,随变形量的增加,材料的加工硬化程度提高,加工硬化速率减小,发生单滑移向多滑移转变的临界应变减小。

The microstructural evolution and mechanical properties of Hastelloy C-276 alloy sheet with different deformations were investigated using the optical microscope（OM）, electron back-scattered diffraction（EBSD）, and tensile test. The results show that dislocation pile-ups and local strain concentration preferentially appear at grain boundaries under the deformation less than 14%. When the deformation is in the range of 14%~30%, a great quantity of dislocation is produced which locate at twin boundaries and within grains, and the dislocation slip leads to high strain concentration within grains. When deformation degree increases from 0% to 30%, the strain concentration degree of grain boundaries increases at first and then decreases, and reaches the maximum at 14%. The Ludwigson model can describe the true stress-true strain curves by the regression fitting. With the deformation degree increasing, the degree of work-hardening improves while the work-hardening rate decreases, and the critical strain of single slip transforming to multiple slip decreases.