Abstract： 13Cr4Ni highstrength 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 highstrength 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.
2021, Vol. 39 
