The Influence of Microstructures on the Notched Tensile Fracture of Ti–6Al–6V–2Sn Welds at Elevated Temperatures

Abstract

Notched tensile tests of Ti-6Al-6V-2Sn welds, which were subjected to distinct post-weld heat treatments (PWHTs), were carried out in air at 150, 300 and 450°C. The results were compared with those of mill-annealed base metal (MB) specimens tested at same temperatures. The notched tensile strength (NTS) of the MB specimens decreased significantly with increasing temperature. Moreover, the welds with high hardness showed notch brittleness at room temperature but had a higher NTS than the MB specimen. The presence of grain boundary a layer promoted grain boundary shear, therefore, reduced its notch brittleness at room temperature for the weld with the PWHT at 704°C (the W-704 specimen). A lack of deformation compatibility at the interfaces between the a and b phases caused interfacial separations in the MB specimen as well as void formation in the W-704 specimen, leading to the low NTS of these specimens at elevated temperatures.KEY WORDS: notched tensile test; Ti-6Al-6V-2Sn; post-weld heat treatment.

Notched Tensile Fracture of Ti–6Al–4V Laser Welds at Elevated Temperatures

“…It was possible that the lack of deformation compatibility between the ¡ and ¢ phases resulted in the low NTS of the MB specimen at 450°C. 16) On the contrary, the fine acicular structures in the form of basketweave in the AW and W-482 specimens were less likely to form interfacial separations and responsible for the higher NTS at elevated temperatures. 16) Furthermore, the improved ductility for the AW and W-482 specimens at 450°C might cause strain-hardening and persist in higher NTS at elevated temperatures.…”

Notched Tensile and Impact Fracture of Ti-15-3 Laser Welds

“…[9,10] In previous studies, sharp notch specimens were used to investigate the effect of microstructure on the notch sensitivity of titanium alloys and welds. [11][12][13] However, little information regarding the mechanical properties of Ti-15-3 welds is available in the literature. [14,15] Accordingly, the objective of the present study was to investigate the NTS and impact toughness of Ti-15-3 laser welds aged at temperatures ranging from 590 K to 866 K (317°C to 593°C).…”

Mechanical Behavior of Aged Ti-15V-3Cr-3Sn-3Al Alloy

“…In the presence of sharp notches, the alloy may become sensitive to brittle fracture under tensile straining [8][9][10]. In prior studies, the influence of microstructures on the notch brittleness of titanium alloys and welds has been investigated by using notched tensile specimen [11][12][13][14]. In this work, two-step and one-step aging treatments for Ti-15-3 specimens were performed to compare the mechanical properties obtained between the two process routes.…”