High Strain Rate Deformation of Ti-6Al-4V through Compression Kolsky Bar at High Temperatures

Published

June 7, 2016

Author(s)

Sindhura Gangireddy, Steven P. Mates

Abstract

An electrical pulse heated Kolsky Bar technique has been developed at the National Institute of Standards and Technology (NIST) to understand dynamic properties of metals. Fast heating rates, of up to 6000 °K/s, and high strain rates, up to 10,000 s-1, permitted by this technique allow us to model extreme physical processes such as machining, explosive impact and other extreme thermo-mechanical events. In this paper, we present our first results from the study of the constitutive response of a popular Titanium alloy, Ti-6Al-4V, using this compression Kolsky Bar. Experiments are conducted at temperatures ranging from room temperature to 1000 °C under a constant loading rate of 2500 s-1 and a heating rate of ~ 1500 °C/s. The dynamic stress-strain results demonstrate significant thermal softening in the alloy that could be described by Johnson-Cook equation with m =0.85 up to 650 °C. Above 650 °C the rate of change in the flow stresses was faster, which is attributed to allotropic transformation that results in a change in the phase fractions of the hcp and bcc phases present in the alloy. Evidence of transformation is observed in the microstructure of post compression specimens which showed an acicular morphology formed from the high temperature bcc phase on quenching.

Proceedings Title

Proceeding of the Society for Experimental Mechanics 2016 Annual Meeting

Conference Dates

June 6-9, 2016

Conference Location

Orlando, FL

Pub Type

Conferences

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Keywords

Kolsky Bar, Ti-6Al-4V, High-Temperature, Dynamic-Response, Thermal-Softening

Citation

Gangireddy, S. and Mates, S. (2016), High Strain Rate Deformation of Ti-6Al-4V through Compression Kolsky Bar at High Temperatures, Proceeding of the Society for Experimental Mechanics 2016 Annual Meeting, Orlando, FL, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=920418 (Accessed December 13, 2024)