TY - JOUR

T1 - Digital image correlation at high temperatures for fatigue and phase transformation studies

AU - Holzweissig, Martin J.

AU - Kanagarajah, Pirabagini

AU - Maier, Hans J.

N1 - Funding information: This work was financially supported by Deutsche Forschungsgemeinschaft within the Transregional Collaborative Research Center TRR 30 ‘Prozessintegrierte Herstellung funktional gradierter Strukturen auf der Grundlage thermo-mechanisch gekoppelter Phänomene’.

PY - 2013/9/19

Y1 - 2013/9/19

N2 - In this study, digital image correlation was used for two widely different cases to assess the potential and the limitations of the technique for applications at high temperatures. Specifically, digital image correlation was employed in high-temperature low-cycle fatigue experiments in a nickel-based superalloy and in phase transformation experiments conducted on bainitic steel in order to shed light on the microstructural processes. Depending on the type of experiments, the microstructure was characterized prior to the experiments (fatigue) or after the experiments (phase transformation). In the fatigue experiments, it was found that the features dominating damage evolution were the dendrites resulting from the solidification of the cast material. In the phase transformation experiments, variant selection is active when stresses are superimposed during the phase transformation process, which resulted in the evolution of transformation plasticity strains. Thereby, mainly the bainite variants oriented along the [101], [201] and [121] directions were observed to grow parallel to the loading axis, which in turn led to transformation plasticity strains. For validation of the digital image correlation data, average strains were calculated for the surface area probed and compared to strain values obtained by conventional extensometry. In all cases studied, the correlation was satisfactory, indicating that digital image correlation can provide for additional insight into processes active at the micro level.

AB - In this study, digital image correlation was used for two widely different cases to assess the potential and the limitations of the technique for applications at high temperatures. Specifically, digital image correlation was employed in high-temperature low-cycle fatigue experiments in a nickel-based superalloy and in phase transformation experiments conducted on bainitic steel in order to shed light on the microstructural processes. Depending on the type of experiments, the microstructure was characterized prior to the experiments (fatigue) or after the experiments (phase transformation). In the fatigue experiments, it was found that the features dominating damage evolution were the dendrites resulting from the solidification of the cast material. In the phase transformation experiments, variant selection is active when stresses are superimposed during the phase transformation process, which resulted in the evolution of transformation plasticity strains. Thereby, mainly the bainite variants oriented along the [101], [201] and [121] directions were observed to grow parallel to the loading axis, which in turn led to transformation plasticity strains. For validation of the digital image correlation data, average strains were calculated for the surface area probed and compared to strain values obtained by conventional extensometry. In all cases studied, the correlation was satisfactory, indicating that digital image correlation can provide for additional insight into processes active at the micro level.

KW - digital image correlation

KW - fatigue

KW - High-temperature

KW - microstructure

KW - phase transformation

UR - http://www.scopus.com/inward/record.url?scp=84899128529&partnerID=8YFLogxK

U2 - 10.1177/0309324713498737

DO - 10.1177/0309324713498737

M3 - Article

AN - SCOPUS:84899128529

VL - 49

SP - 204

EP - 211

JO - Journal of Strain Analysis for Engineering Design

JF - Journal of Strain Analysis for Engineering Design

SN - 0309-3247

IS - 4

ER -