BS in Materials Engineering
Materials Engineering Department
This project attempts to reduce manufacturing costs incurred to Cherry Aerospace by variance in material properties. To track and predict the shear strength of PH 15-7 Mo stainless steel rivet stems throughout the heat treatment process, samples were taken from several steps in the manufacturing process and experimental heat treatments were performed across a range of temperatures. The supplied rivet stems were heat treated for four hours at temperatures from 520°C to 560°C, in increments of 10°C. Double shear testing in accordance with ASTM 1312-13A revealed that there is no apparent correlation between the strength of the supplied wire and final shear strength of the wire. It is recommended that samples be tested for impact toughness to better understand the shear behavior of the rivet stem due to the break notch. When examining the effects of composition on mechanical properties, there is a lack of evidence to suggest that any correlation can be made. Even with constant composition, different lots of wire exhibit variances in shear strength in the fully heat treated condition. It is concluded that the variances in mechanical properties of the rivet stems are influenced by other factors. These could include manufacturing operations that are not included in the scope of this project, such as stackup of tolerances in the rivet assembly or effects of cold work of the wire prior to procurement by Cherry Aerospace.
Available for download on Friday, June 19, 2020