In this study, the microstructure of B319 casting alloys and effects of five different casting conditions on microstructure were studied. Multi-scale microstructure was quantified in terms of secondary dendrite arm sp...In this study, the microstructure of B319 casting alloys and effects of five different casting conditions on microstructure were studied. Multi-scale microstructure was quantified in terms of secondary dendrite arm spacing （SDAS）, and Si particle size and aspect ratio. The effects of SDAS, Si aspect ratio and size on fatigue life were analyzed. The results indicate that the size and aspect ratio of Si particles are a function of SDAS which is dependent on cooling rate during solidification. The fatigue life decreases with SDAS increasing as SDAS is smaller than 30 pm while it increases with SDAS increasing as SDAS is larger than 60 ~tm. In addition, the fatigue life decreases with Si aspect ratio and size increasing at the same SDAS. Moreover, SDAS and Si particles have also influence on fatigue fracture, such as the area of cracks propagation region and the roughness of fatigue fracture. The cracks propagation area is smaller, and the fatigue fracture is similar to tensile fracture with larger SDAS. Besides, the longitudinal section of fatigue fracture is rougher with large SDAS and elongated Si particles.展开更多
基金financially supported by the National Natural Science Foundation of China (No.50771073)General Motors Funded Project (No.1314)
文摘In this study, the microstructure of B319 casting alloys and effects of five different casting conditions on microstructure were studied. Multi-scale microstructure was quantified in terms of secondary dendrite arm spacing （SDAS）, and Si particle size and aspect ratio. The effects of SDAS, Si aspect ratio and size on fatigue life were analyzed. The results indicate that the size and aspect ratio of Si particles are a function of SDAS which is dependent on cooling rate during solidification. The fatigue life decreases with SDAS increasing as SDAS is smaller than 30 pm while it increases with SDAS increasing as SDAS is larger than 60 ~tm. In addition, the fatigue life decreases with Si aspect ratio and size increasing at the same SDAS. Moreover, SDAS and Si particles have also influence on fatigue fracture, such as the area of cracks propagation region and the roughness of fatigue fracture. The cracks propagation area is smaller, and the fatigue fracture is similar to tensile fracture with larger SDAS. Besides, the longitudinal section of fatigue fracture is rougher with large SDAS and elongated Si particles.
