Impact of microstructure, temperature and strain ratio on energy-based low- cycle fatigue life prediction models for TiAl alloys

TL;DR

This study evaluates energy-based low-cycle fatigue models for TiAl alloys, confirming the linear relationship of dissipated energy with fatigue life and highlighting the influence of microstructure, temperature, and strain ratio on prediction accuracy.

Contribution

It compares two dissipated energy-based models, with and without hydrostatic pressure correction, and assesses their effectiveness for TiAl alloy fatigue life prediction.

Findings

Dissipated energy correlates linearly with fatigue life.

Energy-based models are more suitable for low-cycle fatigue estimation.

Microstructure, temperature, and strain ratio significantly affect prediction results.

Abstract

In this paper, two fatigue lifetime prediction models are tested on TiAl intermetallic using results from uniaxial low-cycle fatigue tests. Both assessments are based on dissipated energy but one of them considers a hydrostatic pressure correction. This work allows to confirm, on this kind of material, the linear nature, already noticed on silicon molybdenum cast iron, TiNi shape memory alloy and 304L stainless steel, of dissipated energy, corrected or not with hydrostatic pressure, according to the number of cycles to failure. This study also highlights that, firstly, the dissipated energy model is here more adequate to estimate low-cycle fatigue life and that, secondly, intrinsic parameters like microstructure as well as extrinsic parameters like temperature or strain ratio have an impact on prediction results.