Advances in Titanium Technology: Powder Metallurgy and Additive Manufacturing of Ti and Ti Alloys
Sponsored by: TMS Structural Materials Division, TMS: Titanium Committee
Program Organizers: Don Li, Howmet Engineered Products; Yufeng Zheng, University of North Texas; Peeyush Nandwana, Oak Ridge National Laboratory; Matthew Dunstan, US Army Research Laboratory

Thursday 8:30 AM
March 18, 2021
Room: RM 30
Location: TMS2021 Virtual

Session Chair: Matthew Dunstan, U.S. Army Research Laboratory


8:30 AM  
Development of Cold Spray Additive Technology for Manufacturing Titanium Mill Products: Stefan Gulizia1; Leon Prentice1; Peter King1; Saden Zahiri1; Alejandro Vargas Uscategui1; Christian Doblin1; 1CSIRO Manufacturing
     Cold spray Additive has emerged as a key competitor for existing technologies such as casting, ingot metallurgy and powder metallurgy. It offers a combination lower cost manufacturing with enhanced properties and performance that’s particularly well-suited for manufacturing Titanium shaped intermediates and mill products directly. The property benefits arise from solid state deposition, which promotes microstructural refinement and eliminates macrosegregation. When used in conjunction with novel low-cost titanium metal powder production, Cold spray Additive becomes a transformational manufacturing technology challenging traditional Titanium manufacturing routes. This presentation will describe CSIRO’s patented Cold spray technologies to manufacture continuous mill products such as Billets and Performs, all these directly from low cost Titanium binder-less powder feedstocks. The characterization of the microstructure and mechanical properties produced with different powder feedstocks will be described, together with results of holistic CFD model used to predict temperature, velocity, deposition efficiency and distribution of particles existing the jet.

8:50 AM  
Investigation to Hole Surface Microstructure Evolution in Drilling of Aerospace Alloys: Ti-5553 : David Yan1; 1San Jose State University
    Ti-5553 (Ti-5Al-5Mo-5V-3Cr-0.5Fe) is a newly developed near β titanium (Ti) alloy with excellent fatigue performance and corrosion resistance. Hence, it is of significant importance in several high-performance aerospace applications such as landing gear components and helicopter rotors. The machinability of Ti-5553 is low owing to its high strength at elevated temperature, low thermal conductivity and high chemical reactivity. Although there is a profound knowledge about the machinability of α + β Ti alloys (typically Ti-6Al-4V), there is a lack of understanding regarding the surface microstructure evolution during machining of Ti-5553. This paper presents experimental investigations on the microstructure evaluation in the hole surface produced during drilling of Ti-5553. A series of high-speed drilling tests were conducted to evaluate the influence of cutting conditions on the hole surface microstructure alternation in relation to the cutting temperature. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) technique were used to characterize the hole surface microstructure produced from drilling tests. The precipitation of new α phase from β matrix in the hole surface was observed in dry drilling, however, this phenomenon was not detected in wet drilling with a coolant supplied.

9:10 AM  Cancelled
Process Design for Laser Hot Wire Additive Manufacturing of Ti-6Al-4V: Brandon Abranovic1; Elizabeth Chang-Davidson1; Jack Beuth1; 1Carnegie Mellon University
    This work focuses on parameter development for a large-scale laser hot wire process, consisting of a moving melt pool formed by a laser source and a heated wire fed into the melt pool. Parameter development for a large-scale hot wire feed additive manufacturing process was carried out with the use of semi-analytical welding models and finite element analysis. Initial work consisted of mapping key melt pool dimensions from single bead geometries across process space, then proceeded to stacking single beads into thin walls. Semi-analytical modeling was used to correct flaws in these walls, including selecting interlayer dwell times. Simulation of thin walls was undertaken via a custom FEA model utilizing element birth and death, resulting in temperature histories used for microstructure prediction. Finally, parameter development was extended to complex geometries such pads, cubes, thin walled T junctions, and curved surfaces. The work culminated in the fabrication of a specialized component.

9:30 AM  
Opportunities to Develop Superior Titanium Alloys by Laser Powder Bed Fusion: Marco Simonelli1; Graham McCartney1; Zou Zhiyi1; Nesma Aboulkhair1; Yau Yau Tse1; Adam Clare1; Richard Hague1; 1University of Nottingham
     This talk presents two strategies to address mechanical anisotropy and increase strength/ductility in α + β titanium (Ti) alloys produced by laser powder-bed fusion (L-PBF). The first strategy leverages (i) the α/β orientation relationship, and (ii) the crystallographic defects naturally forming during L-PBF, to induce β grain refinement via specially designed rapid heat treatments. Grain refinement is characterized by high-temperature EBSD (up to 1000 °C) to inform on the early nucleation and growth of recrystallized β grains. In the second strategy, we develop a novel quaternary Ti-6Al-4V-Fe alloy with the aim to increase strength and ductility. L-PBF allows the use of significant Fe contents to generate heat treatable laminar and refined α + β microstructures. Mechanical testing and deformation mechanisms of the new alloys are studied by synchrotron X-ray diffraction, microstructural analysis and fractography. The merits and limitations of this alloy design strategy and future outlooks will be discussed.

9:50 AM  
Towards an ICME Framework of Designing Post-process for Additively Manufactured Ti-6Al-4V: Shengyen Li1; Kirby Matthew1; James Sobotka1; 1Southwest Research Institute
    Metal additive manufacturing produces net-shape products and generally introduces local features that need additional heat treatments to tailor the microstructure to meet performance requirements. This presentation will introduce an ICME workflow to discover the processing-structure-properties relations and optimize post-building heat treatment of AM-built Ti-6Al-4V. In this workflow, we adopt a finite-element, heat-transfer model to simulate AM-building process. Scheil-Gulliver and a martensitic transformation models assist to evaluate micro-segregation and estimate the stability of the BCC phase. This workflow also accommodates a phase transformation model to predict the microstructure evolution through an AM building and subsequent heat-treatments. The predicted microstructure features are the inputs to a mechanistic model to calculate the stress-strain curves. We will exercise this workflow to design a heat treatment to improve the ductility of Ti-6Al-4V. This presentation will summarize the predicted values, including phase fraction, grain size, yield strength, and elongation, to compare to the measured values.