Temperature Dependant Mechanical Property Characterisation Using Digital Image Correlation and Infrared Thermography

Abstract

Accurate mechanical property charac-terisation of high-temperature high-performance materials, such as additively manufactured (AM) Inconel 718 (IN718), is crucial to ensure the reliability of components. A sudden drop in strength accompanied by significant embrittle-ment occurs in wrought IN718 near 700 ◦C. It is not clear whether AM IN718 exhibits this behaviour. The high cost of these materials and manufacturing methods necessitate the development of specimen-efficient testing techniques that allow material properties to be extracted simultaneously over a range of testing conditions. This paper presents a test setup, which is used to determine high-temperature mechanical properties over a range of operating temperatures by integrating digital image correlation (DIC) and full-field infrared thermography (IR). A purpose-designed specimen is resistively heated using a Gleeble 3800 thermomechanical simulator to create a thermal gradient across the length of the specimen. A high-temperature DIC setup and IR camera are used to capture the specimen surface’s displacement and full-field IR data. These datasets are temporally synchronised using a common triggering system and spatially correlated to allow for the extraction of temperature-dependent properties for a range of up to 100 ◦C from a single tensile test. The setup is shown to successfully capture the strength drop-off and embrittlement of AM IN718. Keywords: Full-field, Digital Image Correlation, Infrared Thermography, High-Temperature, Inconel 718