铸钢节点对接焊缝有效缺口应力分析
Effective notch stress analysis of butt weld on cast steel joint

为了研究铸钢节点对接焊缝的疲劳性能和寿命评估方法，对一种常用的铸钢热轧钢对接焊缝试件进行了疲劳试验研究，得到了刚度、位移与疲劳寿命阶段之间的关系。根据疲劳试验现象和断面的电镜扫描结果，提出了该类试件的疲劳失效机理。此外，采用有效缺口应力法预测了铸钢节点对接焊缝的疲劳寿命，并在考虑了平均应力和焊接残余应力的前提下，提出了改进的有效缺口应力法，分别将预测结果与实测疲劳寿命进行了对比。研究结果表明：铸钢节点对接焊缝的疲劳过程可分为稳定阶段和断裂阶段。稳定阶段占总寿命比例≥80%，断裂阶段≤20%。有效缺口应力法能在一定程度预测疲劳寿命的变化趋势，但结果偏危险，改进的有效缺口应力法能提供较安全的预测结果。
In order to investigate the fatigue behavior and fatigue life prediction method of butt weld on cast steel joint, a series of fatigue tests were conducted on welded specimens of cast steel and hot rolled steel with a common welding type. Relationships between stiffness, displacement and fatigue life stage were obtained. Fatigue failure mechanism was revealed based on the phenomenon of fatigue process and fracture surface observation resulted by scanning electron microscope (SEM). In addition, fatigue life prediction was carried out with effective notch stress method (ENSM). In consideration of the influence of mean stress and residual stress, improved effective notch stress method (IENSM) was proposed, and the predicted values were compared with the test data. The result shows that:The fatigue process of butt weld on cast steel joint can be divided into two stages:stable stage and fracture stage. The stable stage possesses more than 80% fatigue life, while the fracture stage maintains less than 20%. ENSM can predict the changing trends of the fatigue life to some extent, but the results are non-conservative for engineering. However, IENSM can provide safe assessments.