Q460D高强钢及其焊缝连接疲劳性能试验研究

在疲劳荷载作用下钢结构焊缝区易发生疲劳断裂，通过Q460D高强钢及其焊缝连接的疲劳性能试验研究，结合试验数据，拟合了Smax-N曲线预测其疲劳寿命，根据疲劳损伤理论分析了疲劳破坏程度，并通过断口形貌揭示了疲劳裂纹扩展规律。研究结果表明：Q460D母材具有较高的疲劳抗力；对接焊缝接头Smax-N的95%保证率曲线与ANSI/AISC 360-10的疲劳设计曲线吻合较好；GB 50017—2003的设计曲线能较好预估循环次数大于40万次以上十字接头的疲劳寿命。损伤指标能够较好地表征疲劳破坏过程中构件内部状态的变化，缺口系数越大，损伤发展越快。瞬断前裂纹扩展规律与损伤发展一致，随着损伤发展疲劳条带间距逐渐变大。

Experimental study on fatigue performance of Q460D high-strength steel and its welded joints

The weld zone of steel structure is prone to fatigue fracture under fatigue load. The fatigue properties of Q460D high-strength steel and its welded joints were studied，and on the basis of the experimental data, the Smax-N curve was fitted to predict the fatigue life. According to the theory of fatigue damage, the degree of fatigue failure was analyzed, and the fatigue crack growth law was studied by fracture morphology analysis. Results show that the Q460D base metal exhibits high fatigue resistance. The Smax-N 95% survival probability curve of butt joints is in excellent agreement with the curve specified in ANSI/AISC 360-10. The GB 50017—2003 design curve can be used to predict the fatigue life of the cruciform joints with more than 400 thousand cycles. The damage index can be used to characterize the change of the internal state of the component in the process of fatigue failure. The larger the notch coefficient, the faster the damage develops. Crack propagation rule is consistent with damage development before the instant fracture. Along with the development of the damage fatigue striation spacing becomes larger.