Scaling relationships in sharp conical indentation of shape memory alloys

Abstract

Based on dimensional analysis and finite element calculations, several scaling relationships in the indentation of shape memory alloys with a sharp conical indenter were obtained. These scaling relationships illustrate the dependence of the indentation response on the material properties of shape memory alloys, such as phase transition and plastic deformation. It is shown that the yield stress and strain-hardening exponent of transformed martensite play important roles in the indentation response, in addition to the phase transition properties. Additionally, the general relationships between indentation hardness and phase transition stress, maximum transition strain, martensite yield stress and the strain-hardening exponent of shape memory alloys were obtained. The results show that the indentation hardness of shape memory alloys is not proportional to the phase transition stress or to the martensite yield stress, and cannot be used directly to measure the phase transition stress or the yield stress of shape memory alloys.

Keywords:

• indentation
• indentation hardness
• shape memory alloys
• finite element modelling

Acknowledgements

The authors are grateful to the two reviewers for their constructive comments for improving the article. This study is supported by the Program for New Century Excellent Talents at University (NCET 05-0796) of China. GK acknowledges his visiting academic residency at Monash University on the invitation by WY.