Papers by Keyword: WE43

Abstract: In this study to the authors knowledge 1^st time, Metal Injection Molding (MIM) technique was used to introduce the magnesium alloy WE43 into binder-based powder metallurgical (PM) processing. Towards later adoption to binder-based 3D-printing technologies, Fused Granular Fabrication (FGF) technique, respectively for biomedical application. Metal Injection Moulding (MIM) is a binder based economic near net shape prototyping technique for production of complex shaped parts in high number and high reproducibility, and hence perfect as a “gold standard” for the introduction of new Mg-alloys into binder passed PM processing. In doing so, dogbone shape tensile test specimen were manufactured by MIM, subsequently solvent debound and conventional sintered in argon atmosphere. Next to the as sintered specimens (asS), solid solution heat treatment (T4) and precipitation hardening heat treatment (T6) were performed on additional specimens. Tensile tests pointed out high strength and ductility of as sintered and heat treaded specimens of up to 226 MPa UTS at 7.6% elongation at fracture. The microstructure was investigated using SEM imaging technique equipped with energy disperse x-ray energy analysis (EDX) for secondary phase analysis. Hence, the magnesium alloy WE43 could be identified as a high strength and ductility alloy for binder based PM processing for future additive manufacturing approaches in biomedical applications of patient adapted implants.

Abstract: Magnesium (Mg) and its alloys have been intensively investigated as potential biocompatible materials with appropriate structural, mechanical and corrosion properties for preferable orthopedic applications. Selective Laser Melting (SLM) technique was developed for the fabrication of three-dimensional components with high structural integrity at a low cost and is compatible with various materials, including biocompatible magnesium alloys. In this study, WE43 magnesium alloy samples produced by SLM technique were examined by in vitro static test in Hank's balanced salt solution (HBSS) under physiological temperature conditions for six days. A hydrogen evolution method for the estimation of the corrosion rate was used. The phase composition of samples before and after the immersion test was investigated by X-ray diffraction (XRD). The surface morphology and chemical composition of the initial material and tested samples were characterized by scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDX).

Abstract: Magnesium alloys are important engineering materials due to their good combination of strength and very low densities. However, the low ductility imposed by the hcp-lattice has thus far limited the application of magnesium alloys as sheet material. The use of the electroplastic effect offers a route to increase formability of magnesium alloys while being more energy efficient than conventional hot forming. The underlying mechanism (s) of this effect have not yet been fully understood. This study investigates the impact of high current density electrical pulses on magnesium alloys. Special consideration was given to the effect of the orientation of the applied electric current relative to the mechanical loading of the specimens. The results show that the mechanical properties of coarse-grained materials are more strongly affected by the current pulses than finer grained material. Applying the current parallel to the compressive load shows a more pronounced softening of the material than pulses applied perpendicular to the mechanical stress. Microstructure investigations revealed the formation of twinning solely in the interior of grains even at stresses below the yield point for both configurations.

Abstract: This article shows the extension of an empirical model for the numeric calculation of the spread during rolling Freiberg in calibres developed at TU Bergakademie to Mg alloys AZ31, AZ81 und WE43.The material independent foundations were developed at the Institute of Metal Forming at TU Bergakademie Freiberg.The Freiberger spread model has, through numerous rolling trials and examinations of the material flow, been broadened. Furthermore, the results of the calculations were compared with these trials.The Freiberger model for spread takes the geometrical input and output parameters into consideration, as well as the material flow, the deformation rate v, the deformation temperature θ, the chemical composition of the material C_w, longitudinal tension CL, and friction C_μ between the rolling stock and rolls. And it further considers the diagonal ratio C_A∗a_KNⁿ of the box pass and the filling ratio of the box pass m.

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Magnesium alloys are widely used mainly in automotive and aerospace industries. There is quite a lot of information about corrosion of the magnesium alloys in available literature. However, the publications concern mainly Mg-Al alloys, while there is a lack of information about Mg-RE-Zr alloys. The following paper presents results of the investigations on the electrochemical corrosion of magnesium casting alloys containing rare earth elements (WE43, WE54, EV31A-Elektron 21) as well as pure magnesium. The alloys were investigated by immersion test in 3.5% NaCl for times up to 7 days. Electrochemical investigations were carried out at ambient temperature in aerated NaCl solution, using potentiodynamic polarization method. It has been shown that the best corrosion resistance is exhibited by alloys with yttrium addition (WE43, WE54), while the weakest by pure magnesium. EV31A alloy exhibits the highest corrosion rate during the immersion test, while WE54 and WE43 alloys had a similar corrosion behavior.

Abstract: Mg-Y-Nd (WE43) plate in 3mm thickness was friction stir welded (FSW) under a tool rotation rate of 800rpm and a traverse speed of 100 mm/min. The super plastic deformation structure was obtained in as-FSWed WE43 alloy. Coarse equiaxed recrystallized microstructure in extruded WE43 alloy with the average grain size of over 50μm changed into fine equiaxed recrystallized grains with the average grain size of under 5μm in the FSW core zone. The formation and evolution of hardening precipitates in WE43 alloy during ageing at 210^oC is characterized by transmission electron microscopy (TEM) and high resolution electron microscopy (HREM) observations. It was indicated that the microstructure of as-FSWed WE43 always contain β’’ phase even without heat treatment. The hardening is mainly associated with the β’’→β’ transformation.

Abstract: Non-metallic inclusions in Elektron 21 and WE43 magnesium alloys have been investigated by means of scanning electron microscopy. Investigations were conducted both on the fracture surfaces and microsections. Researches revealed presence of alloying elements oxides, inclusions originating in mould material and inclusions originating in the fluxes covering liquid metal surface in the cruicible. The number of inclusions is reduced by application of complex gating system and by leaving small amount of alloy in the cruicible after the pouring process.

Abstract: In addition to aluminium and titanium alloys, the magnesium alloys comprise the group of lightweight alloys which have the highest practical importance in structural applications. The WE43 alloy with the addition of rare earth elements and yttrium is used mainly for the sand mould castings for the aerospace industry. The castings for aerospace industry have complicated shapes and varying wall thickness, as a result of which they often have casting effects such as misruns, micro-shrinkages and cracks. The frequency of defect occurrence in the complicated shape casting may exceed 50%. The defects are repaired by means of welding and pad welding. Such practice is often used in foundries. The paper presents the results of repair evaluation of the WE43 alloy castings in the as-cast state by means of the TIG welding. The welding tests have been performed on the joints bevelled to “I”, “Y” and “V” and the technological repair guidelines have been formulated. The defect has been repaired and the non-destructive and structural tests have confirmed that the technology is correct. The WE43 alloy should be welded and pad welded with maximum linear arc energy of 3.0 kJ/cm, straight beads, with filler metal of a similar chemical composition, in the as-delivered state.

Abstract: The deformation and recrystallization behavior of two magnesium alloys, AZ31 and WE43, have been investigated. The cast alloys were heat treated to produce various distributions of second phase particles and deformed in a channel die at a strain rate of 10-4 s-1 at temperatures between 523 and 673 K. The alloys were subsequently annealed at temperatures between 708 and 798 K.The AZ31 and WE43 were extruded at 555 and 633 K, respectively. The microstructures were compared to those developed during channel die deformation. The tensile and compressive strengths and the texture of the alloys were determined in the as-extruded and recrystallised conditions.Optical microscopy and electron backscattered diffraction (EBSD) were used to characterize the microstructures of the alloys. The EBSD technique was used to determine the texture of the deformed and annealed samples.

Abstract: The deformation and recrystallization behaviour of two magnesium alloys, WE43 and an experimental “Alloy A1” containing a large amount of second phase, have been investigated. Optical microscopy and electron backscattered diffraction (EBSD) were used to observe each alloy after deformation in a channel die at 553 and 558 K and subsequent recrystallization during annealing at 673 K. Alloy A1 dynamically recrystallised during deformation at 553 and 558 K. In WE43 the particle distribution affected the onset of dynamic recrystallization. Both alloys exhibited evidence of particle stimulated nucleation (PSN) of recrystallization at second phase particles as well as recrystallization at pre-existing grain boundaries. The A1 and WE43 alloys were extruded at temperatures of 573 K and 633 and 663 K, respectively. The extruded microstructures were compared to those that developed during channel die deformation.