Effect of Groove Angle on Microstructure and Fatigue Properties of K-butt Joint
In order to solve the problem of groove Angle selection of K groove butt joint of Q450NQR1 weathering steel,this paper takes 45°,50° and 60°K groove butt joint as the research object,metallographic and fatigue tests are carried out on the three kinds of groove Angle butt joint,and the influence of groove Angle on the metallographic distribution and fa-tigue performance of the joint is analyzed.In addition,the fracture characteristics and mechanism are analyzed by scanning observation of fatigue fracture.The test results show that the microstructure composition of the butt joint is similar in each area of the groove Angle,and the grain width of the weld column and grain size of the coarse-grain zone are proportional to the groove Angle.The fatigue limits of 45°,50°,60°K beveled butt joints are 151 MPa,147.5 MPa,135 MPa,and the fa-tigue limit is inversely proportional to the beveled Angle.The fracture initiation zone and the extension zone of the fatigue specimen have typical fatigue fracture characteristics,there is obvious fatigue arc in the extension zone,and the typical dimple structure can be observed in the final fault zone.The larger the Angle of the groove,the more sparse the fatigue arc and dimple structure in the extended zone.