COMPARATIVE ASSESSMENT OF COLD SPRAY, LASER ASSISTED COLD SPRAY, AND DIRECT METAL LASER SINTERING OF TI-6AL-4V

Open Access
Author:
Trowbridge, Michael J
Area of Honors:
Interdisciplinary in Engineering Science and Mechanical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Timothy Eden, Thesis Supervisor
  • Sean Brennan, Honors Advisor
  • Timothy Simpson, Thesis Supervisor
Keywords:
  • cold spray
  • laser-assisted cold spray
  • direct metal laser sintering
  • selective metal sintering
  • titanium
  • Ti-6Al-4V
  • additive manufacturing
  • characterization
  • porosity
  • microstructure
  • hardness
Abstract:
Ti-6Al-4V is an α-β titanium alloy that continues to be widely used in the aerospace and medical industries due to its corrosion resistance and impressive strength-to-weight ratio. Ti-6Al-4V’s high manufacturing time and cost make the alloy an excellent candidate for near-net shape fabrication. However, fabrication processes often introduce thermal effects that transform the microstructure and degrade mechanical properties. Cold spray (CS) avoids such thermal effects by achieving bonding through kinetic energy. However, Ti-6Al-4V’s toughness limits particle deformation and leads to deposition porosity. This investigation examines the effects of several parameters on the coating microstructure and porosity, including driving gas selection, hot isostatic pressing, and laser-assisted cold spray (LACS). Furthermore, the porosity and microstructure of the CS and LACS specimens were compared to a Direct Metal Laser Sintering (DMLS) specimen. Ultimately, eight series of specimens were analyzed across a range of fabrication processes, parameters, and post-process conditions. The results provide a better understanding of the microstructure of sprayed and printed Ti-6Al-4V and form a foundation for future mechanical testing of these processes.