1985 Volume 49 Issue 8 Pages 614-619
The influence of the notch shape on the elongation has been investigated for a Sn-38.1 mass%Pb superplastic alloy, using specimens with a couple of various V-type notches or a small hole-type notch.
It seemed that the elongation of the notched specimens had a correspondence with the ratio of the cross-sectional area of the specimen, An⁄As, where An: the minimum area appearing at the bottom of notch and As: the original area in smooth part. However, since the concept based on the ratio itself had no consideration on any significant difference due to the shape of notch, the analysis could not explain the variation in the elongation of specimens with the different shape of notch. Therefore, according to a simple model proporsed for superplastic deformation, which was taking acount for distributions of both the strain rate and the m-value over the gage length on the specimen, a comparison between the experimental elongations and the calculated values through the present model was carried out systematically. Finally, it has been shown clearly that the both are in a fairly good agreement. It has been also considered that the flow stress during superplastic deformation up to before the fracture is almost directly related to the true strain rate.
