Abstract
The hot workability of metallic materials is significantly dependent on its ability to form plastic without cracking and fracturing. In this work, the cracking behavior of powder metallurgy (PM) Ti-5Al-5Mo-5V-3Cr (Ti-5553) alloy, consolidated from powder mixture, at a deformation temperature range of 600 °C–850 °C and strain rate of 0.1 s−1–10 s−1, was investigated through isothermal compression tests. The cracking behavior of the as-cast ingot metallurgy (IM) Ti-5553 alloy, at a deformation temperature of 700 °C was also investigated for comparison. Results suggested that the PM Ti-5553 alloy had a better hot workability, with a larger cracking-free processing window, and a lower deformation resistance than the IM counterpart. 45° shear fracture occurred in the PM alloy, compressed at the condition of 600 °C/10 s−1, and edge cracking was observed at the 700 °C/10 s−1. 45° shear fracture was also significant in the IM alloy specimen tested at 700 °C/10 s−1, and all the other IM alloy specimens compressed at 700 °C displayed longitudinal cracking. Moreover, the microscopic cracking observation showed that ductile dimple cracking can be found in the IM alloy, but brittle cleavage fracture was dominant in the cracking surface of PM alloy with a relatively low cracking ductility.
Highlights
Titanium and its alloys are attractive materials in aerospace, chemical, marine, and civil applications, due to their excellent properties, including low density, high specific strength, good corrosion resistance, and great high-temperature properties [1,2,3,4,5,6]
Much finer microstructure can be found in the powder metallurgy (PM) alloy (Figure 1a showing an average grain size of 100 μm) than the ingot metallurgy (IM) alloy (Figure 1b, showing an average grain size of 1000 μm), and some residual pores can be identified in the microstructure of the PM alloy
A typical β grain matrix can be observed in, both, the PM and the IM alloy, and the IM alloy was composed of a large number of dispersed α phase, which was spread over a β matrix, while only a small amount of the agminated α precipitates could be seen in the PM alloy, mainly distributed along β grain boundaries [19,25]
Summary
Titanium and its alloys are attractive materials in aerospace, chemical, marine, and civil applications, due to their excellent properties, including low density, high specific strength, good corrosion resistance, and great high-temperature properties [1,2,3,4,5,6]. Ti-5553 (Ti-5Al-5Mo-5V-3Cr) is a near beta high strength titanium alloy and was developed from the Russian VT-22 alloy, for the application of aerospace industry, particular in thick forged components (such as the Boeing-787 and Airbus-350 aircrafts’ landing gears and flap tracks), due to its ultra-high strength, good fatigue resistance, and deep hardenability [7,8,9,10,11]. The powder metallurgy (PM) approach has been verified to be a cost-effective processing technique to produce titanium alloy products that meet the requirement of the industrial applications, with additional benefits, such as the manufacture of near-net-shape parts and optimization of the microstructure [13,16,17]. Utilizing rapid consolidation processing methods, such as hot pressing and powder forging, instead of conventional vacuum sintering and hot isostatic pressing (HIP) processes, the titanium alloy products can be produced in a much shorter process and their costs can be reduced significantly [18,19].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
