The effect of manufacturing processes on the mechanical properties of MO40 aviation bolts

Fatigue life is very important in components which are under cyclic stress in their working service. One of these components is the aviation bolt typically produced in two ways: machining and cold rolling, after applying a quench-temper heat treatment. In this study, the material was produced from MO40 steel after a quench-temper heat treatment through two methods: cold rolling and machining; and the fatigue strength, hardness, and tensile properties were investigated. The results showed that bolts manufactured using the cold rolling method had more appropriate fatigue properties at the same hardness even though the tensile strength did not change much. This is due to compressive stresses occurring in the cold rolling process, non-cutting of materials, and the continuous flow of materials in cold-rolled threads in comparison to those in the machining method. The results also showed that with the tempering temperature increasing from 520°C to 580°C, fatigue strength and tensile strength decreased due to the decreased hardness and softened structure.

کلیدواژه ها:

lifetime Fatigue ، Bolt ، Mo40 Steel ، produce thread.