孔间厚度对双孔法测定材料局部强度的影响及方法改进

The effect of thickness between double holes in double-holes micro-shear method on the determination the local strength of the material and method improvement

摘要:

工程上对金属材料进行承载能力评定时,需测定各区域的局部强度。在双孔微剪切试验的基础上,研制可稳定加载的双孔微剪切试验新装置,构建荷载位移同步检测的LabVIEW系统,并对12Cr13、S31608和16Mn三种钢材料进行多组双孔试验；借助标准拉伸试验,通过对试验数据的分析,研究孔间厚度对荷载位移试验曲线的影响,并给出归一化参数 与屈服强度,归一化参数与抗拉强度的相关关系,实现由双孔试验曲线的特征值和孔间厚度一同求取局部强度参数。试验结果表明,孔间厚度的微小变化对荷载位移曲线具有明显可测的影响,且应用改进的装置以及归一化参数来测定12Cr13、S31608和16Mn局部强度的方法,可以有效地减小孔间厚度对测定精度的影响。

Abstract:

The test for local strength of metallic materials is necessary for load capacity estimation of the metallic materials. A new test apparatus with stable loading has been developed, and a LabVIEW system for simultaneous detection of load and displacement has been established based on the double-hole micro-shear test method. Tensile and double-hole tests have been carried out on martensitic stainless steel, austenitic stainless steel and high-strengthSlow-alloy steel at room temperature. The material thickness between doubles holes effect on the micro bend-shear test curves is discussed, and the method of applying the normalized parameters and related to the thickness to obtain the local strength parameters has been proposed. The test results show that a slight change in thickness has an obvious measurable effect on the load-displacement curve. It has been validated that the use of improved apparatus and the correlation between standardized parameters and strength parameters to measure the local strength of materials can effectively reduce the influence of thickness on measurement accuracy.