建筑用抗震钢HRB400EⅢ级钢筋焊接接头的低周疲劳性能

采用轴向应变控制方法,在MTS809拉扭复合疲劳试验机上开展了HRB400EⅢ级钢筋母材及焊接接头的低周疲劳试验,获得了母材及焊接接头的低周疲劳性能,如循环应力响应特征、循环应力-应变关系以及寿命预测公式等.通过断口电镜扫描发现,HRB400EⅢ级钢筋焊接接头的裂纹萌生于试件表面,且存在多处裂纹源.研究结果表明,焊接接头与母材的低周疲劳寿命及微观断裂机理方面均存在明显差异,并从力学性能变化的角度对引起差异的原因进行了解释.

Investigation on the Low Cycle Fatigue Properties of the welded joint of HRB400E III aseismic reinforced bars

Welding connection is the most common connection mode used in steel structures. The low cycle fatigue (LCF) behavior of the welded joint of the HRB400E III aseismic reinforced bars promoted in the earthquake areas in China was investigated in this paper. The LCF tests under uniaxial strain control were carried out on a MTS809 servo-hydraulic testing machine. The low cycle fatigue properties, such as the cyclic stress response characteristics, the cyclic stress-strain relationships and the fatigue life prediction models of the base metal and the welded joint were obtained. The Coffin-Manson parameters were derived from the test results. The SEM micrographs revealed that more than one fatigue cracks initiated at the specimen surfaces. The results show that the low cycle fatigue life and the micro fracture mechanism of the welded joint are obviously different from those of the base metal. And the reasons for the obvious difference of the LCF property and the micro fracture mechanism of the welded joint were revealed from the change of the mechanical properties.