A revolutionary method for manufacturing superalloy components has been perfected by US company Howmet, a subsidiary of Thiokol, after it met the high vacuum requirement for casting with highly reactive metals present.
The company has formed Howmet Metal Mould at its Whitehall, Michigan base, and says it is in "closed talks with a number of aerospace manufacturers" about applying the technology. US engine manufacturer Pratt & Whitney commissioned the company to produce a test component just weeks after the realisation of the breakthrough, says Howmet, which adds that previous attempts to cast aerospace parts of high enough quality failed to produce a high enough vacuum.
One of the most promising superalloys to benefit from the process will be Vitreloy, a metallic-glass Zirconium alloy patented by the California Institute of Technology. Howmet says Vitreloy has no grain boundaries when cast using the new process, with grain size as low as 100 microns - an order of magnitude finer than with existing processes.
"We are looking at a couple of dozen applications," says Howmet, starting with golf clubs. Aerospace superalloys formed with the new process and tested with a hot isostatic press exhibited a 10-12% higher yield strength and ductility 20-50% higher than those of investment cast components, claims Howmet.
The process also saves production time and costs.
Source: Flight International
