Papers by Author: F.H. Froes

Abstract: Titanium is the “wonder” metal, which makes sense as the material of choice for a wide variety of applications. However, because of its relatively high price- a result of extraction and processing costs- it is used basically only when it is the only choice; with the caveat that titanium has a bright “image” which can lead to use even when the economics are unfavorable. The major thrust in the area of titanium technology has been aimed at achieving cost reduction rather than developing alloys with enhanced properties. This paper will overview the potential areas which are amenable to cost reduction and present some applications of titanium and it’s alloys.

Abstract: The as-cast and hot worked microstructures of the newly developed β-solidifying ingot-metallurgy Ti-45Al-X (Nb,Mo,B) alloy and its superplastic properties in the hot worked condition have been studied. The obtained experimental findings were used for research of superplastic forming and diffusion bonding of sheet products, which were cut out of hot worked preform by spark cutting. It was shown that superplastic forming might be successfully applied to the obtained fine-grained sheet materials. Relatively low bonding temperatures and pressures were found to be sufficient to achieve sound joints in the sheet material.

Abstract: The availability to produce Ti-6Al-4V sheet material with submicron-grained microstructure for superplastic forming (SPF) has been studied. The laboratory scale sheets with an average grain size of 0.3 μm and the commercial size sheets with an average grain size of 0.65 μm were produced by pack rolling manufacturing technique from the forgings with pre-formed submicrocrystalline (SMC) structure. The sheets possessing isotropic mechanical properties in the sheet plane had higher yield strength, ultimate tensile strength. Over the exceptionally low temperature range of 700-750°C the SMC sheets demonstrated enhanced superplastic properties, namely an initial flow stress of 20-25 MPa and elongation more than 600% at the strain rate of 3×10-4/s. The sheet material with SMC structure was characterized by well formability compared to a conventional sheet under low temperature superplastic conditions.