Production of Nanostructured Fasteners with High Shear and Fatigue Strength for Using in Aircraft Components

Abstract

Multi-axis forging (MAF) and cyclic heat treatment are among the most widely used and easy to apply grain refinement methods. In this study, micro-alloyed steel samples were first subjected to MAF treatments at 880° C. Microstructural analysis showed that the average grain size, which was 13.2 µm initially, decreased to 11.2 µm application of the MAF. As a second-grain refinement technique, cyclic heat treatment was used. Samples were subjected to 1, 3, 5, 7, and 10 cyclic quenching. With this method, it was observed that the average grain size decreased to 2,3 µm. The mechanical tests showed that the second MAF process increased the yield and tensile strength of the material by about 16% while decreasing the elongation by %2. These tests also presented cyclic quenching increased tensile strength of the samples after the first application.