In-situ monitoring of phase transformation in Ti-6Al-6V-2Sn using laser ultrasonics

Abstract

Titanium is of great interest for metal processing industries due to its superior material properties, but it is also quite expensive. Therefore, a detailed knowledge of α → β phase transformation and consequential the distribution of α and β phase in titanium alloys is crucial for their material properties and as a consequence for further processing steps. Measuring the ultrasonic velocity and attenuation by laser ultrasonics (LUS) technology as a non-destructive and non-contact technique, it is possible to monitor in-situ the phase transformation with high accuracy during heating the sample from room temperature up to 900 • C. We validate LUS methodology against high energy X-ray diffraction as well as against conventional metallurgic measurements and get excellent agreement between the results of these methods.

In-situ measurement of the β to α phase transformation kinetics in a Ti-5553 alloy using laser ultrasonics

“…Zamiri et al [17] observed the sensitivity of LUS in detecting phase transitions in a Ti-6Al-4V wt.% alloy during continuous heating. Attempts to validate LUS measurements in Ti-systems were later done by Hinterlechner et al [19]. Aided by synchrotron X-ray diffraction, a good agreement was observed between the change in wave velocity and the α dissolution during continuous heating of an α+β Ti-alloy [19].…”

“…Laser ultrasonics sensing (LUS) has been identified as a useful tool to measure phase transformations in metals and alloys [14][15][16][17][18][19]. In addition to being in-situ, it is a non-contact and non-destructive technique that permits real-time tracking of microstructure evolution during complex thermomechanical processing, which is advantageous from the industrial perspective.…”

“…Phase transitions can be determined by this technique because the ultrasound velocity depends on the elastic properties and density of the investigated material [20], which typically change with phase fractions and crystallographic texture. Although LUS has been developed in the past three decades, there is still a limited number of publications on the usage of this technique for phase transformation measurements in titanium and Ti-alloys [17][18][19]. Zamiri et al [17] observed the sensitivity of LUS in detecting phase transitions in a Ti-6Al-4V wt.% alloy during continuous heating.…”

“…Attempts to validate LUS measurements in Ti-systems were later done by Hinterlechner et al [19]. Aided by synchrotron X-ray diffraction, a good agreement was observed between the change in wave velocity and the α dissolution during continuous heating of an α+β Ti-alloy [19]. However, investigations on the complete α+β → β transformation were not performed by Hinterlechner et al [19].…”

Microstructural and Very High Cycle Fatigue (VHCF) Behavior of Ti6Al4V—A Comparative Study

“…This lightweight yet strong alloy saves weight in highly loaded structures and hence is extremely suitable for gas turbines and many airframe components as well as for automotive components and biomedical devices [12,13]. The characteristics of each titanium alloy grade are different and used for various purposes.…”