小冲孔能量法评价Q345R的屈服强度

小冲孔试验技术(SPT)是测量在役构件材料力学性能的新方法。文章介绍了基于弹性能量理论预测材料屈服强度的小冲孔能量法,并对试验原理及步骤进行了详细阐述。在验证试验重复性的基础上,对Q345R进行小冲孔能量法试验,并与常规拉伸试验、小冲孔偏移法和双斜率法的结果进行对比。结果表明,能量法测试Q345R屈服强度的误差为5.52%,远小于双斜率法和偏移法试验结果的误差。在此基础上,根据有限元模拟,结合载荷-位移(L-D)曲线与能量-位移(E-D)曲线,分析了试样厚度、压球直径、下模孔径、冲压速度以及试样边缘减薄等因素对小冲孔能量法结果的影响。得出试样厚度0.5mm、压球直径2.4mm、下模孔径4mm为最佳几何尺寸搭配。

Study on yield strength of Q345R by energy method of small punch test

As a new method with little damage,small punch test(SPT) technique can evaluate mechanical properties of in-service component materials.This article introduced the energy method of small punch test based on elastic energy theory to predict the yield strength.Meanwhile,the experimental principle and procedures were described in detail.The experimental results of SPT energy method for Q345 were compared with those of conventional tensile tests,small punch offset method and two-tangent method.The results showed that the error of energy method was 5.52%,much lower than the errors calculated by offset method and two-tangent method.The effects of sample thickness,steel ball diameter,center hole diameter of the lower die,punching velocity and edge thickness decreasing on SPT results were analyzed by finite element analysis(FEA),based on Load-displacement(L-D) curve and Energy-displacement(E-D) curve.The optimal parameters were proposed as the sample thickness 0.5mm,the steel ball diameter 2.4mm and the center hole diameter of the lower die 4mm.