Papers by Keyword: Wrought

Abstract: The enhancement of efficiency in gas turbine engines requires the development of new superalloys capable of withstanding higher temperatures. The development of novel industrial cast and wrought (C&W) disk alloys with required combination of strength, creep and fatigue resistances at 700°C is particularly desired due to the expensive cost of powder metallurgy. In this context, new C&W disk alloys were recently developed to fulfill these requirements. TMW4 shows higher properties than the current C&W disk alloy despite an expensive cost due to its high cobalt content, where as 718Plus presents a moderate cost with restricted creep properties at 700°C compared to the current U720Li disk alloy. The new nickel base superalloys developed by Aubert & Duval were therefore designed to offer a better compromise between high temperature properties at 700°C and cost. This paper describes the alloy metallurgical features and is especially focused on the alloy design which is extensively based on phase diagram modeling. The study was firstly carried out on small ingots of 6 kg to optimize the chemistry before forging 200 kg ingots by industrial processes. The ability to be processed by the conventional cast & wrought route and the control of the highly expensive elements contents confer to the alloys an attractive cost comparable to that of 718Plus alloy. The high amount of ’ and the molybdenum-tungsten levels insure higher creep and tensile properties than those obtained with 718Plus.

Abstract: Expanding world economic prosperity and probable peaking of conventional petroleum production in the coming decades requires efforts to increase the efficiency of, and the development of alternatives to, petroleum-based fuels used in automotive transportation. North America has been aggressively pursuing both approaches for over ten years. Mainly as a result of lower prices due to global sourcing, magnesium has recently emerged as a serious candidate for lightweighting, and thus increasing the fuel efficiency of, automotive transportation. Automotive vehicles produced in North America currently use more Mg than vehicles produced elsewhere in the world, but the amounts per vehicle are very small in comparison to other materials such as steel, aluminum and plastics. The reasons, besides price, are primarily a less-developed state of technology for Mg in automotive transportation applications and lack of familiarity by the vehicle manufacturers with the material. This paper reviews some publicly-known, recent, present and future North American research and development activities in Mg for automotive applications.

Abstract: The hot compression simulation of an experimental Mg-Zn-Nd alloy at different temperatures is studied by the Gleebe-1500 equipment. The deformation is performed with the strain rates 0.1s-1, 0.01s-1 and 0.002s-1. The plastic deformation behavior is analyzed at different temperatures and the deformation activation energy is calculated. The microstructures of experimental alloy during the deformation process are observed. The results show that the working hardening, dynamic recovery and dynamic recrystallization (DRX) operate under different temperatures and strain rate. The DRX starts when the temperature is over 473K and the DRX grain size after hot deformation is only 5~10μm. So the refined grains improve both the tensile strength and elongation of alloys at room temperature. The precipitate phase Mg12Nd impede the movement of dislocations, it benefit to the mechanical properties and grain refining of magnesium alloy.