GB/T 228新标准速率控制模式对屈服强度的影响

Effect of rate control mode in new standard GB/T 228 on yield strength

在GB/T 228征求意见稿中规定了方法 A和方法 B速率控制模式,主要分为基于引伸计反馈的应变速率控制,以及根据平行长度估计的应变速率,即通过控制平行长度与需要的应变速率相乘得到的横梁分离速率。采用GB/T 228新标准中规定的不同速率控制模式对连续屈服和不连续屈服试样材料屈服强度(规定塑性延伸强度)进行试验,探讨了不同速率控制模式对于材料屈服强度的影响。结果发现,对于连续屈服试样采用应变速率控制和估计的平行长度应变速率控制,其性能指标未见明显差异。不连续屈服试样当无需ReH时,可以采用应变速率控制或估计的平行长度应变速率控制。当需要ReH时,应采用估计的平行长度应变速率控制。

Two rate control modes,i. e.,Method A and Method B,are specified in the draft of GB/T 228,which are mainly divided into strain rate control based on extensometer feedback and strain rate estimated according to parallel length,that is,the beam separation rate obtained by multiplying the parallel length by the required strain rate. Two different rate control modes specified in the new standard GB/T 228 were employed to test the yield strength (specified non proportional elongation strength) of continuous yield and discontinuous yield specimens. The influence of rate control mode on the yield strength of materials was discussed. The results showed that the performance indexes of continuous yield specimens had no significant difference when adopting strain rate control and estimated parallel length strain rate control. For the discontinuous yield specimens,when ReH was not required,it could be controlled by strain rate or estimated parallel length strain rate. However,when ReH was required,it should be controlled by estimated parallel length strain rate.