Influence of the cold expansion process on fatigue performance of hard alloys holes

摘要

This paper presents an evaluation of the influence of the cold expansion process on fatigue performance of holes in hard alloys, as such materials are involved in an increasing number of aeronautic applications. Although the cold expansion of aluminium holes has been studied widely, there have been few reports concerning this issue in hard alloys. Some studies do, however, show that fatigue gains can be observed by using an extension of the processes employed on aluminium. Currently, there is no research concerning dedicated techniques to expand hard metals, despite their highly specific behaviour. In this article, the response of Ti-6Al-4V expanded holes is studied, considering various experimental parameters such as the stack thickness and hole diameter. The influence on the fatigue strength of tensile specimens is also presented for various expansion rates. Thus, this work aims to define an approach to understand which processes and methodologies are suitable for obtaining effective expansion of hard metals.