Extreme High Speed Laser Application for Titanium Cylinders Bores

Across the aerospace industry, mission critical components are manufactured from titanium due to its high strength to weight ratio. When these high-cost components are subject to extreme operating environments, they can fail prematurely due to excessive wear and/or early fatigue.  Current coating technologies address these issues but still fall short of desired performance.  A need has been identified for an improved coating that does not damage the substrate or affect the titanium alloy and that can be finish machined to function as an actuator bore.A promising new coating technology termed Extreme High Speed Laser Application (EHLA) has been developed and commercialized in Germany and China.  Contrary to traditional laser cladding, EHLA sets the focal point of the laser beam and introduces the cladding media well above the substrate, while also moving at rapid relative speeds.  The result is a wear and corrosion resistant coating deposited in very thin layers (~0.1mm thick), while minimizing the Heat Affected Zone (HAZ) (< 75um thick).  The cladding is deposited in multiple layers to achieve the desired thickness with no increase to the HAZ.  Minimizing the HAZ is critical to maintaining fatigue characteristics of the substrate material and therefore the entire component.  Different cladding media will be evaluated under this proposal, with Kennametal’s suite of Stellite alloys of particular interest for wear, galling, and corrosion resistance.EHLA can increase the wear and corrosion resistance of these components but will not be able to extend the fatigue life beyond that of the as-manufactured component.  Ormond proposes using its Cavitation Peening (CP) process prior to coating to improve component fatigue life. In CP, a high-pressure liquid jet causes intense cavitation bubbles directed to collapse on the surface of a submerged component.  This generates shock waves that induce deep residual compressive stresses, which greatly improve fatigue characteristics of as-manufactured components.  CP has been commercialized for nuclear energy and food processing industries and is being evaluated by many other organizations for various applications.For this solicitation, Ormond proposes a 4-step manufacturing process.  1) Cavitation peen the Ti-6-4 forging for extended fatigue life, 2) EHLA clad a wear and corrosion resistant coating, 3) use various machining processes to achieve desired surface finishes, 4) cavitation peen the cladding for further fatigue life improvement and texturizing of the surface for oil retention.Each of these 4 steps must be able to be applied in non-line-of-site (NLOS) configurations to meet the Navy’s Phase II and III goals of cladding a 3-1/2” bore at 12” length.  This is already standard at Ormond for cavitation peening, surface finish improvement machining, and traditional laser cladding.  Ormond plans to use this SBIR to modify their internal bore, traditional laser cladding equipment to perform the EHLA process.