Hot Spot Stress Analysis In Different Girth Butt Welding Details Of Cast Steel Joint

The girth butt welding attaching the cast steel joint and the hot-rolled tube has beenan important object on the fatigue study of the cast steel joint due to the materialnonlinearity and geometric nonlinearity across the welding. However, the research onthis issue was rarely seen in our country.The nominal stress method is not applicable to the cast steel joint. In this study, thehot spot stress method is used to analyze the fatigue behavior of the girth butt welding.First, it introduces the theory and the FEM analysis of hot spot stress method, the resultsof different hot spot stress extrapolations are compared. Second, different weldingdetails are suggested to reduce the impact of the stress concentration. The study offeredthe hot spot stress and the ShsCF which under consideration of the tube’s thickness andthe other two parameters. At last, the study compared the fatigue performance of caststeel joint with different welding details.The study comes to a conclusion that,1) Of all the mentioned hot spot stress extrapolations, ShsCFs derived by IIW arebigger than those derived by DNV. The quadratic solutions are bigger than the linearsolutions.2) According to the different welding details of cast steel joint mentioned above,the thickness has little influence on the ShsCF. While T/t increases, the ShsCF decreases.While d/t increases, the ShsCF increases.3) The results show that, when the thickness is less than20mm, the ShsCF of the Itype welding detail is smaller than the Y type, which means the I type’s fatigueperformance is better than the Y type; and when the thickness is more than25mm, theShsCF of the Y type welding detail is bigger than the U type, which means the U type’sfatigue performance is better than the Y type.4) The fatigue performance turn out to be better when the cast steel joint hastransition.