Papers by Author: Werner Beck

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: Superplastic forming (SPF) is well known in aircraft production of Titanium and Aluminium parts. The process technology is commercially interesting for small quantities. The advantage of low upfront cost for the tooling is quickly lost however in conjunction with the longer cycle times of forming under purest SPF conditions. At given production rates typical for the aircraft industry the technology has an economical advantage over conventional, ambient temperature sheet metal forming processes. Compared to established processes the break-even point is at about 400 to 4000 parts/year, depending on the metal alloy and the geometry. Transfer to high volume production as afforded by automotive production of niche products calls for a modified forming process and an optimisation of the production flow. One alternative for a modified process is called “Hot Gas Pressure Forming” (HGPF). This process is very comparable to SPF, but the applied strain rates are much higher than recommended for SPF. HGPF can be applied in combination with a pre-forming operation done by cold or hot forming. The production line which has to be created to establish a constant production flow of outerbody parts like doors, inner and outer, fenders, bonnet and trunklid, inner and outer and roof for a project with an annual production quantity of ~30 to 40 000 cars has been engineered on the basis of the material’s forming behaviour studies, process investigations, cost analysis studies, etc. The elements of the production line like presses, interstockers, transportation , etc have been defined and placed with the help of a production simulation tool to get the best efficiency combined with suitable flexibility.

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.