影响HRB600螺纹钢筋强屈比的因素

Factors Influencing Tensile to Yield Ratio of HRB600 Reinforced Bar

在多次进行拉伸试验时发现,用同一炉钢制作的HRB600螺纹钢筋的强屈比存在较大差异。通过大量的对比试验研究了影响HRB600螺纹钢筋强屈比的因素。结果表明,自然时效时间对钢筋的强屈比有较大的影响。随着自然时效时间的延长,下屈服点下降,导致强屈比增大;数据采样频率和拉伸速率对下屈服点的判定也有一定影响,然而对抗拉强度影响不明显。数据采样频率为10 s^(-1)时,应力-应变曲线上的局部数据点未采集到,导致下屈服点明显上升;拉伸速率增大时,下屈服点上升,导致强屈比减小。因此,为准确测定HRB600螺纹钢筋的强屈比,自然时效时间应大于96 h,数据采样频率不小于30 s-1,弹性段至屈服段的拉伸速率为10～15 mm/min,塑性段为75 mm/min。

From multiple tensile tests it was found that HRB600 reinforced bars made from the same heat of steel exhibited more significant difference in their tensile to yield ratio.The factors influencing the tensile to yield ratio of the HRB600 reinforced bar were investigated by using a large amount of comparative tests.The results showed that the natural aging time had a great influence on the tensile to yield ratio of bar.As the natural aging time increased,the lower yield point fell,resulting in increase in the tensile to yield ratio.Frequency of data sampling and tensile rate of the tester also affected the determination of the lower yield point but had no appreciable influence on the tensile strength.When the frequency of data sampling was 10 s-1,data points on the stress-strain curve missed,causing the lower yield point rose significantly.As the tensile rate increased,the tensile to yield ratio decreased because of the raise of lower yield point.Therefore,in order to accurately determine the tensile to yield ratio of the HRB600 reinforced bar,the natural aging time should be over 96 h,the frequency of data sampling preferably is over 30 s-1,and the tensile rates should be 10 to 15 mm/min at elastic to yielding stage and 75 mm/min at plastic stage.