尺寸效应对小冲杆试验方法评价拉伸性能的影响

INFLUENCE OF SIZE EFFECT ON EVALUATION OF TENSILE PROPERTIES USING SMALL PUNCH TEST

为探究尺寸效应对小冲杆试验结果的影响,对镍基合金Incoloy 800H和低合金钢3Cr1MoV开展不同厚度试样(100~500μm)的小冲杆试验,并通过Ludwig硬化模型和有限元方法构建不同试样厚度下的力-挠度曲线和真应力数据库。基于数据库和小冲杆试验曲线获取不同试样尺寸下的真应力-塑性应变曲线。在此基础上预测了材料的强度性能,并建立了试样尺寸和流动应力以及强度性能的关系。结果表明,Incoloy 800H的拉伸性能随着试样厚度的减小逐渐增加,而试样尺寸对3Cr1MoV的拉伸性能影响很小。就拉伸性能对厚度不同的依赖关系进行探讨,为小冲杆试验方法预测拉伸性能时试样厚度的选择设计提供了依据。

In order to explore the effect of the specimen size on results of small punch test(SPT),SPT was conducted on Incoloy 800H and low alloy steel 3Cr1MoV using various specimen thicknesses of 100~500 μm,and a database of force-deflection curves and true stresses were created for various specimen thicknesses by Ludwig hardening model and finite element method.True stress-plastic strain curves of different specimen sizes were acquired based on the database and SPT experimental curves.The strength properties of the studied materials were predicted through these true stress-plastic strain curves.Meanwhile,the relationship between flow stresses,strength properties and specimen size was obtained.The results show that tensile properties of Incoloy 800H increase gradually with the decrease of sample thicknesses,while sample sizes have a slightly influence on tensile properties of 3Cr1MoV.The different responses of tensile properties to thicknesses were discussed,which provides a basis for the selection and design of sample thickness when SPT is employed to predict tensile properties.