Effect of Casting Defects on Mechanical Properties of Steel Structures with Cast Steel Joints

In order to study the influence of the grade size and position distribution of casting defects on the static and fatigue properties of steel castings, firstly, a three-dimensional solid steel truss model with cast steel joints was built by Solidworks, and the size and location of casting defects on the cast steel joints were determined based on the published literature; then, the truss structures containing different casting defects were subjected to static loading, and the stress distribution and displacement distribution of the structure were analyzed to determine the influence of casting defects on its static strength and static stiffness; finally, the truss structures with different casting defects were subjected to equal amplitude fatigue loading, and the local fatigue life of the model was obtained through the modified S-N curve of the cast steel joint to clarify the effect of casting defects on it fatigue performance. The results show that when the different positions of the cast steel joints contain casting defects with the same size, the maximum difference in maximum stress of different models is 11.7%, the fatigue life of the different models differs by two orders of magnitude. When the same position of the cast steel joint contains casting defects of different sizes, the maximum difference in maximum stress of different models is 1.7%, the fatigue life of the different models differs by one orders of magnitude. In spite of the different positions of the cast steel joints contain casting defects with the same size or the same position of the cast steel joint contains casting defects of different sizes, there is no significant effect for the overall and local displacement distribution of the structure. When the distribution of casting defects in the cast steel joint changes, the rate of change of maximum stress between different models is 8.8%, the fatigue performance between different models is inferior to the model that only contains one casting defect.