600 MPa级钢筋高温下力学性能的试验研究

Experimental research on mechanical properties of 600 MPa steel rebar in high temperature

为得到600 MPa级钢筋高温下的力学性能,对600 MPa级钢筋进行了恒温加载和恒载升温2种温度-应力途径下的强度试验和高温下的变形试验。结果表明:屈服强度和极限强度都随着温度升高而降低,在400~600℃内下降最快,但屈服强度的下降速率大于极限强度的下降速率;在300~700℃内,恒载升温途径下的强度略大于恒温加载途径下的强度,在该温度范围外2种途径下的强度相差不大;应力-应变曲线与常温下的差别较明显,随温度升高,屈服台阶逐渐消失,强化区段逐渐缩短,在400℃时极限延伸率降至最低,在500~800℃仅由斜率逐渐减小的上升段和峰值点后较平缓的下降段组成;弹性模量随温度升高而降低,自由膨胀变形却呈幂函数增长趋势。

In order to get the mechanical properties in high temperature,the strength and deformation experiment of 600 MPa steel rebar in temperature-stress is done. One is steady state test and the other is transient test. The experiment results show that,with the rise of temperature,the ultimate strength and yield strength is decreased,particularly between 400 ℃ and 600 ℃ and the declining rate of yield strength is faster than ultimate strength. In temperature between 300 ℃ and 700℃,the strength in the second way is slightly higher than that in the first one. Beyond that,the strength in the two ways has a little difference. The stress-strain curve under high temperature is significent different with it in normal temperature. With the rise of temperature,the yield step is disappeared and the strengthening segment is shortened gradually. When the temperature is 400℃,the ultimate elongation decreases to the minimum. It is composed of the rising slope with decreasing gradient gradually and gentle decline after peak point between 500 ℃ and 800 ℃; With the rise of temperature,the elastic modulus decreases and free expansion deformation shows a growth trend of the power function.