高强钢规定塑性延伸强度测定方法

以13Cr4Ni高强钢材料为例，探讨在室温拉伸变形过程中曲线无明显屈服平台，且初始阶段加工硬化率较高，通过常规检测，其拉伸曲线弹性段曲率不一致，使得规定塑性延伸强度并不是一个稳定的值。采用区别于GB/T 228.1的新滞后环法，选择滞后环起点为高于材料弹性极限值，低于预期的规定塑性延伸强度，滞后环下反向点为滞后环起点的10%应力值，在这个区间内进行试验，均得到较稳定的规定塑性延伸强度值。试验结果表明：高强钢及具有相似特征的材料在室温拉伸时，可采用本试验给出的方法，选取对应取值范围中的滞后环起点及滞后环下反向点，得到稳定的、可参考的规定塑性延伸强度值。

Determination method of specified plastic #br#extension strength of high strength steel

13Cr4Ni high strength steel material was selected as an example. It was found that the curve had no obvious yield platform during the room temperature tensile deformation process, and work hardening rate was relatively high in the initial stage. Through the routine testing, the curvature of the tensile curve in elastic section was inconsistent, resulting in unstable values of the specified plastic extension strength. A new hysteresis loop method which was different from GB/T 228.1 was adopted to measure the extension strength. The starting point of the hysteresis loop was selected to be higher than the elastic limit value of the material and lower than the expected specified plastic extension strength, and the reverse point under the hysteresis loop was 10% of stress value of the starting point of the hysteresis loop. The tests were conducted within this interval, and a relatively stable specified plastic extension strength value could be obtained. The results showed that when the tensile experiment of the high strength steel and materials with similar characteristics at room temperature was measured by the proposed method in this study, a stable specified plastic extension strength value could be obtained by selecting the starting point of the hysteresis loop and the reverse point under the hysteresis loop as the test range.