桥梁钢Q420qD断裂韧度CTOD失效评定图评估方法

CTOD evaluation of bridge steel Q420qD by failure assessment diagram method

由于桥梁钢断裂韧度CTOD评估时没有相应的产品标准或者行业规范规定其允许值δmin,无法直接开展韧度评估,因此提出了采用失效评定图评估方法将断裂试样假定为带缺陷构件的间接评估方法,并依据此方法完成了桥梁钢Q420qD的焊接接头母材、焊缝、热影响区的断裂韧度CTOD评估,验证了该方法的可行性。评估结果表明,桥梁钢Q420qD母材和热影响区相对焊缝更安全,焊缝在常温下断裂韧度CTOD合格,但低温下极有可能开裂。

Because there was no product standard or industrial criterion to specify the allowable value of fracture toughness CTOD（δmin） during evaluation of bridge steel,the toughness was hardly directly evaluated. An indirect method adopting failure assessment diagram was proposed for the evaluation of fracture toughness of bridge steel. In this method,the fractured sample was assumed as defective components. Then,the fracture toughness CTOD evaluation of bridge steel Q420qD including welding joint base material,welding bead and heat-affected zone were carried out. The feasibility of this method was verified. The results showed that the base material and heat-affected zone were safer than the welding bead. The fracture toughness CTOD of welding bead was qualified at normal temperature. However,the fracture possibility of welding bead at low temperature was very high.