Papers by Keyword: Light Metal

Abstract: Weight reduction in automotive and aerospace components can improve energy efficiency, reduce emissions, and increase performance. The adoption of light metals such as aluminium, magnesium and titanium alloys, is essential to these performance improvements; however, these alloys require protective surface coatings to prevent corrosion and resulting mechanical failures during service life. Traditional protective coatings for light-weight materials can be costly in terms of energy, raw materials, and environmental sustainability. New durable coating approaches are required to allow light-weight materials to be fully exploited in high performance applications. Novel Cirrus HybridTM coatings, a recent innovation in surface finishing, can protect a wide range of light metal alloy components using a sustainable, non-toxic process. Cirrus HybridTM coating technology deposits a thin-film, inorganic coating that bonds tightly to the light-metal alloy substrate. The process is energy efficient, does not rely on hazardous chemicals, and is up to 5 times thinner than traditional coatings for light metals. A Cirrus HybridTM coating provides excellent anti-corrosion, scratch, and wear properties, along with superior tribological, electrical, and optical performance. This paper updates the art of these innovative new coating technologies for reducing weight in industrial components without compromising functionality or performance.

Abstract: A6N01 (6005C in ISO) base metal is applied for cantilever type fatigue test over 10⁸ cyclic number. Fatigue strength decreases over 10⁷ and after testing, new prediction formula of fatigue life at high cycle regeion which named YENs formula is proposed for light metal and their welded joints. This formula is shown as below. Log (σa/σp) =k Log (Nf-N₀)+m σa is stress amplitude, σp is proof stress k is depend on stress concentration factor Nf is fatigue life without residual stress and No is discrepancy due to residual stress. m is material constant. This formula is a hypothesis and it is required to accumulate much more fatigue data for many kind of alloys and their welded joints.

Abstract: The formability of the magnesium-lithium alloy was examined by multi-stage deep drawing. Long cups of magnesium alloy were formed at ambient temperatures by multi-stage deep drawing processes. In multi-stage deep drawing, the magnesium-lithium alloy sheets were employed and a flat sheet blank is formed into a cylindrical by a punch. Various cups were drawn by exchanging the punch and ringed die. The die was flat in the first stage, and was taper without a blankholder in the subsequent stages. The effects of the ratio of blank diameter to punch diameter and blank thickness on the deep drawability were examined. It was confirmed that the Mg-Li alloy long-cups were successfully formed by a multi-stage deep drawing operation in cold.

Abstract: High-energy X-rays and neutrons offer the large penetration depths that are often required for the determination of bulk properties in engineering material research. In addition, new sources provide very high intensities on the sample, which can be used not only for high spatial resolution using very small beams, but also for high time resolution in combination with a fast detector. This opens up possibilities for a wide range of specific engineering in situ experiments. Typical examples that are already widely used are heating or tensile testing in the beam. However, there are also more challenging experiments in the field of light metals, like e.g. friction stir welding, dilatometry, solidification, or cutting. Selected examples are presented.

Abstract: Fatigue crack growthresistance is critical to the design and performance of structural components.This study focuses on understanding the microstructural mechanisms of fatigue crack propagation in commonly used structural materials, cast and wrought aluminum and titanium alloys, with various microstructures resulting from changes in chemistry or heat treatment (A535-F, 6061-T6, and mill- and b-annealed Ti-6Al-4V).Stress ratio effects were evaluated by conducting fatigue crack growth tests on compact tension specimens at low, intermediate, and high stress ratios, R=0.1, 0.5, and 0.7, respectively. Initial flaw size effects were also studied by performing small crack growth tests at R=0.1. Data reduction strategies compensating for closure and K_max effects on crack growth and design curves will be presented.

Abstract: Stress-controlled load increase and constant amplitude tests have been carried out in a temperature range of -60°C < T < 20°C at the aluminium alloy AlMg4.5Mn (EN AW-5083). Therefore a recently developed climate chamber which operates with liquid nitrogen was mounted on a servo-hydraulic fatigue testing machine to realize the required low temperatures. Beside conventional mechanical hysteresis measurements, electrical resistance and temperature measurements are used to characterize the fatigue behavior. Furthermore, with these methods, the endurance limit was successfully estimated in a load increase test. Woehler curves were determined with constant amplitude tests at different temperatures. The conventionally determined endurance limit corresponds with the value from the load increase test.

Abstract: Composites are most promising materials of recent interest. Metal matrix composites (MMCs) possess significantly improved properties compared to unreinforced alloys. There has been an increasing interest in composites containing low density and low cost reinforcements. Hence, composites with fly ash as reinforcement are likely to over come the cost barrier for wide spread applications in automotive and small engine applications. AA 2024 alloy – 2 to 10% (by weight) fly ash composites were made by stir casting route. Phase identification and structural characterization was carried out on fly ash by X-ray diffraction studies. Scanning electron microscopy and optical microscopy was used for microstructure analysis. The hardness, density and compression tests were carried out on all these alloy and composites. The SEM studies reveal that there was a uniform distribution of fly ash particles in the matrix phase and also very good bonding exists between the matrix and reinforcement. With increasing the amount of fly ash the density of the composites was decreased and the hardness was increased. The increase in compression strength was observed with increase in amount of fly ash.

Abstract: A new ECAP process method called rotary-die ECAP (RD-ECAP) was developed to form fine-grained bulk materials such as aluminium alloys, magnesium alloys, aluminium composites, and titanium, all of which can be processed under conditions of 573-773K, at an approximately 0.9-2.4 mm/s punch speed of 300MPa or lower. By the RD-ECAP method, ECAP processing of up to 2 passes can be done without sample removal and samples processed over 30 cycles were obtained.

Abstract: New cup-type diamond-grinding-wheels with hexagonal pattern have been developed. Grinding stone ratio, R is defined as the ratio between the hexagonal edge area containing abrasive grains and the total area of the wheel surface. In the present work, four kinds of hexagonal grinding wheels with different R (13 %, 19 %, 25 % and 36 %) and a conventional wheel (R: 100 %) were used to grind a light metals, which was represented by magnesium alloy AZ31B. Efficiency of abrasive grains and ground surface for machining a light metals were evaluated by calculating the number of abrasive grains which pass through a unit length of a sample surface for each grinding pass, Ng. The results show that surface roughness becomes smaller, i. e., smoother surfaces as Ng increases. Surfaces ground by the conventional wheel are rougher than those by using newly developed hexagonal grinding-wheels in spite of the larger Ng for the conventional wheel. Surface roughness data forms one curve in roughness vs. Ng graph for all hexagonal wheels, and forms another curve for the conventional grinding-wheel. The difference of two curves indicates that the number of effective working abrasive grains in hexagonal wheels is about 5 times higher than that of the conventional wheel. The similar results were obtained for machining sapphire according to our previous work. Hexagonal wheels show higher abrasive grain efficiency for machining not only hard-to-machine ceramics but also light metals such as magnesium alloys than conventional wheels.

Abstract: Nano-structured metals have attracted growing research interest, which has brought about the development of methods for their fabrication. A number of fabrication methods involve severe plastic deformation, SPD, and involve refinement of the coarse-grained structures to grain sizes on a nanometre scale. Such grain refinement is accompanied by a significant improvement in mechanical strength. The improved properties of the nano-structured metals open up perspectives for their application in innovative industries such as aerospace, surface transport and biomedical implant manufacturing. The advantage of using nano-structured light metals is possible weight reduction of manufactured components. In the case of automotive parts, this may contribute to a reduction in CO2 emissions – one of the most important global challenges – due to the significantly higher strength of nano-structured metals and alloys compared to their microcrystalline counterparts. Nano-structured metals also exhibit high strain rate superplasticity at relatively low temperatures. This offers fast processing of materials, whose superplastic forming would be restricted otherwise. Finally, nano-structured metals also possess improved functional properties such as wear and corrosion resistance, which can broaden the range of applications of engineering metals and alloys even further. This paper reviews recent progress in the development of light nano-engineered metals and alloys. In particular, interest is concentrated on the metals and alloys processed by SPD methods. Conclusions are drawn with regard to future development of light materials for application in transport.