Influence of Notch Shapes on Impact Toughness of Fe-based Sintered Material

Impact toughness is one of the important indexes to judge properties of the material. The impact toughness values of the same material under different notch shapes are different. The effect of notch shapes on the impact toughness, fracture morphology and micro crack morphology near the fracture surface was investigated by the impact test at room temperature. There were five kinds of notch shapes, i.e., semicircular-type notch, U-type notch, I-type notch, V-type notch and no notch, and the V-type notch had three kinds of angle:45°, 90° and 120°. The results show that the average value of impact toughness of the no notch specimen was 9.86 J·cm^-2 which was far beyond the impact toughness of notch specimens. The impact toughness values of semicircular-type notch specimen and U-type notch specimen were 2.70 J·cm^-2 and 2.46 J·cm^-2 respectively, and the latter was a bit smaller than the former. The impact toughness values of I-type notch and three kinds of V-type notch specimens were very similar, and they were lower than that of U-type notch specimen. The impact fracture of no notch specimen had obvious deformation, many cracks generated near the fracture, and the cracks distributed widely. However, the plastic deformation of impact fracture of the notched specimen was not obvious, there were a few cracks near the fracture, and the cracks were limited near the fracture.