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Existing high-strength low-alloy steels have been in place on landing gear for many years owing to their superior strength and cost performance. However, there have been major advances in improving the strength of high-performance corrosion-resisting steels. These materials have superior environmental robustness and remove the need for harmful protective coatings such as chromates and cadmium now on the list for removal under REACH legislation. A UK government-funded collaborative project is underway targeting a refined specification Custom 465 Ò precipitation hardened stainless steel to replace the current material on Airbus A320 family aircraft main landing gear, a main fitting component developed by MessierBugatti-Dowty. This is a collaborative project between Airbus, Messier-Bugatti-Dowty, and Carpenter Technology Corporation. An extensive series of coupon tests on four production Heats of the material have been conducted, to obtain a full range of mechanical, fatigue, and corrosion properties. Custom 465 Ò is an excellent replacement to the current material, with comparable tensile strengthand fracture toughness, better ductility, and very good general corrosion and stress corrosion cracking resistance. Fatigue performance is the only significant area of deficit with respect to incumbent materials, fatigue initiation being often related to carbo-titanium-nitride particles and cleavage zones.

Abstrmt -The relationship between microstructures and magnetic properties of NdFeB ribbons or flakes produced by twin-roller quenching was investigated. Dependent on the process parameters magnetically isotropic cell structures or anisotropic columnar structures were obtained. The magnetic properties of the columns did not meet the expections. High press forces on the rollers did not improve the anisotropy of the partially pulverized flakes. The results are discussed in terms of constitutional conditions and deformation mechanisms.

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Thermomechanical processing is a technique used to control the microstructure of steel, however steels which have are exposed to corrosive environments, high temperatures and dynamic loads will show evolutions in the microstructure from the initial product. The behavior of steel in moderate to high temperatures is especially relevant in applications such as internal combustion engines and nuclear power plants due to the long periods of time spent at elevated temperatures [1,2]. The segregation and precipitation of solutes in complex steel alloys can be studied in situ using a variety of high resolution microscopy methods in order to provide a more detailed understanding of these mechanisms.Uranga and colleagues are currently conducting a research project to develop microalloyed steels. The segregation and precipitation of carbon and microalloying elements during and after phase transformations in these steels can be better understood by conducting and analyzing experiments in situ. Increased demand for thin slab direct rolled (TSRD) steels, due to improvements in the mechanical properties of these steels, gives impetus to the quantification of the wide range of microstructures exhibited by TSRD products [3]. Novotny and colleagues at Carpenter Technology Corporation have recently developed a line of steel alloys that exhibit a combination of high toughness and ductility while retaining high hardness and strength [4]. An analysis of the effect of solute additions during alloy processing is required to understand the evolution of the microstructure and its influence on the properties of these alloys.We will analyze samples of steel from CEIT and Carpenter Technology Corporation utilizing a variety of methods. The primary experimental technique will be in situ microstructural evolution using in-TEM annealing coupled with energy dispersive spectroscopy. Electron Backscattered Diffraction (EBSD) will be employed to observe grain orientation, while techniques such as local electrode atom probe (LEAP) will be used to assess solute and precipitate location and chemistry. The data attained throughout this project will be used to develop a detailed view of segregation and precipitation of alloying elements in these steels when they are subjected to thermal treatments. This knowledge will provide a basis for improving processing techniques and an understanding of the behavior of the microstructure of these steels in high temperature applications. References [1]Nobuhiro Fujita, HKDH Bhadeshia and Masao Kikuchi. Modelling Simul. Mater. Sci. Eng. 12 (2004) 273.