Microstructural analysis of spall damage nucleation and growth in multicrystalline titanium

Elizabeth V. Fortin, Andrew D. Brown, Leda Wayne, Pedro Peralta

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Shock loading is a dynamic condition that can lead to material failure and deformation modes at the microstructural level such as cracking, void nucleation and growth, and spallation. Knowledge of shock loading and spall failure is of great benefit to understanding ballistic impact in military vehicles and armor, crash impacts in automobiles, space vehicles, and satellite loadings, and geological events such as earthquakes. Furthermore, studying material failure at the microstructural level is important to understand macroscale behavior. Spallation, the nucleation, growth, and coalescence of voids, is a phenomenon where variability at the microscale can affect overall response. By analyzing incipient and intermediate damage patterns at and around interfaces and boundaries on the microstructural level, can help further our understanding of the process leading to damage and provide insight on how to develop stronger structures that can withstand impacts and rapid crack propagation. Most of the existing work has looked into the effect of grain boundaries in spall damage for body and face centered cubic (BCC, FCC) materials, but research is still lacking on grain boundary effects in spall damage in hexagonal close packed materials, such as titanium. Samples of high purity Ti were heat treated to obtain large grains, averaging 250 microns in size (multicrystals), in order to isolate grain boundary effects. These multicrystals were shocked using laserlaunched flyer plates at the Trident laser at Los Alamos National Laboratory (LANL) and monitored using a velocity interferometry system for any reflector (VISAR). Pressures used were 5 - 8 GPa. Samples were soft recovered and crosssectioned to perform quantitative characterization of damage. Spallation damage observed in the titanium targets was characterized using electron backscattering diffraction (EBSD), optical microscopy, and scanning electron microscopy (SEM) to gather information on the crystallographic characteristics of damage nucleation sites, with emphasis on grain boundaries and grain orientations that lead to damage localization. Initial results show that damage localized along grain boundaries, and the damage mode switched from intergranular to transgranular where grains were larger than average.

Original languageEnglish (US)
Title of host publicationMechanics of Solids, Structures and Fluids; NDE, Diagnosis, and Prognosis
PublisherAmerican Society of Mechanical Engineers (ASME)
Volume9
ISBN (Electronic)9780791850633
DOIs
StatePublished - 2016
EventASME 2016 International Mechanical Engineering Congress and Exposition, IMECE 2016 - Phoenix, United States
Duration: Nov 11 2016Nov 17 2016

Other

OtherASME 2016 International Mechanical Engineering Congress and Exposition, IMECE 2016
CountryUnited States
CityPhoenix
Period11/11/1611/17/16

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ASJC Scopus subject areas

  • Mechanical Engineering

Cite this

Fortin, E. V., Brown, A. D., Wayne, L., & Peralta, P. (2016). Microstructural analysis of spall damage nucleation and growth in multicrystalline titanium. In Mechanics of Solids, Structures and Fluids; NDE, Diagnosis, and Prognosis (Vol. 9). American Society of Mechanical Engineers (ASME). https://doi.org/10.1115/IMECE201667667