A Surrogate Approach to Reveal Microstructural Mechanisms Controlling the 3D Short Crack Growth in a Ti-6Al-4V Alloy

Meysam Hassanipour,Kyosuke Hirayama,Akihisa Takeuchi,Han Li,Kentaro Uesugi,Shinta Watanabe,Hiroyuki Toda

doi:10.1051/matecconf/202032111004

Meysam Hassanipour, Kyosuke Hirayama + Show 5 more

Open Access

https://doi.org/10.1051/matecconf/202032111004

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Abstract

Microstructural features and short crack growth behavior were characterized and linked in a Ti-6Al-4V by employing X-ray micro-tomography combined with EBSD serial sectioning. Statistical analysis was used to rank the contributing features to the crack behavior. Afterwards, by creating surrogate models, the microstructural mechanism controlling the short crack behavior were revealed. Short crack preferably grows inside the predominant α phase above the average microstructural fraction. A high number of grains in contact with cracked α grains elongated in the loading direction may impose a constraint on the crack opening resulting in low crack growth rates. As the crack front becomes larger, the increase in the shear stress field away from the cracked grain leads to crack bifurcations, resulting in a decrease in crack driving forces with low crack growth rates. This leads to a preferable growth in α+β phase and along the interface above the average microstructural fractions.

Highlights

There is an ongoing research in order to fabricate alloys with enhanced mechanical properties [1,2]
This stress distribution leads to an increase in crack growth in α+β phase and along the interface above the average microstructural fractions
Afterwards, by creating surrogate models, the relationship between the most contributing microstructural features and short crack growth behavior were further analyzed via support vector machines

Summary

Introduction

There is an ongoing research in order to fabricate alloys with enhanced mechanical properties [1,2]. Different fabrication process such heat treatment, rolling, etc., are employed in order to make alloys with predominant features (e.g., grain size) to estimate the correlation with local properties (e.g., crack growth) [3,4,5]. In order to reach a 3D, in-situ, and representative analysis, X-ray microtomography can be employed By using this type of observation in one specimen, a large number of local features and their properties can be linked with 1 μm of spatial resolution. Afterwards, using the global sensitivity and principal component analysis, the contribution of microstructural features controlling the short crack growth were ranked. By creating surrogate models the relationship between the most contributing microstructural features and crack growth behavior were determined and the micromechanisms can be revealed

Material and experimental procedures

Results

Discussion

Conclusions