Abstract: In this study, a novel method of mechanical interlocking of super-thin stainless steel strands with different aluminum alloys was conducted by using friction stir forming (FSF). The potential for the development of a multi-functional composite material was studied experimentally. It was concluded that FSF can successfully interlock stainless steel strands and different Al alloys and presents the possibility of improving the mechanical properties of the alloy. Trials of FSF were carried out on a modified vertical milling machine. The results are discussed in terms of microstructure observations, hardness distributions and tensile tests.
Abstract: This paper describes a production process for experiment and finite element method (FEM) analysis of cold forming of SUS304 pipe. These large diameter pipes such as φ114.3 mm are used for a plant as a flow channel of gas and liquid. The connection of pipes are generally welded at the plant. However, the other connecting method are required from a viewpoint of making the plant environment worse by welding. Therefore, flaring process of large diameter pipes were proposed. This flaring process is one of a method of pipe flange forming. The formed pipes were connected used with loose flange. Flaring process was generally hot process, thus it has some problem such as becoming complex of forming machine and accuracy of dimension. In this study, cold flaring process of SUS304 pipe was proposed to satisfy these requisitions. Experiment and FEM analysis of cold flaring process were performed to clarify the optimum forming conditions for the flat length of connecting surface such as a diameter of punch, punch stroke and taper angle of dies. As a result, a gap between punch and die was needed to match the pipe wall thickness.
Abstract: This study suggests a novel method to detect wrinkles using the frequency characteristic of reflected ultrasonic wave. The experimental apparatus was manufactured to simulate the press forming. A plate specimen possessing periodic wrinkles in a trapezoidal shape was also prepared to simulate actual wrinkles during the press forming process. These wrinkles affected the reflected wave of ultrasonic wave. The power spectrum of reflected wave at a frequency of 0.8 MHz was changed by the occurrence of wrinkles. The comparison of the frequency characteristics provided obvious difference between wrinkled and flat specimens. As a result, the present work confirmed that the frequency characteristic of reflected wave would detect the formation of wrinkles.
Abstract: Friction-stir forming (FSF) is a friction-stir process invented by Nishihara in 2002. In FSF, a material is put on a die, and friction stirring is then conducted on its back surface. The material deforms and precisely fills the cavity of the die due to high pressure and heat caused by friction stirring. Materials in the process often display outstanding deformability and moldability. However, behavior of the material during the friction-stir process has not been sufficiently clarified as a metal forming process. In this paper, material deformability under a tool in spot FSF, i.e. FSF without tool travel, was investigated employing a die having holes. The authors conducted spot FSF on 3mm-thick A5083P-O aluminum plates at offsetting points from the center of a hole and evaluated the height and volume of cylindrical extrusions to evaluate the deformability distribution under a tool. In addition, forming pressure distribution on the die surface was evaluated by an embedded pressure pin connected with a load sensor. The authors conducted spot FSF on 3mm-thick A5083P-O aluminum plates at offsetting points from the center of a pin as well as deformability tests and evaluated forming pressure compiled from the bearing load of the pin. In the deformability test, the extrusions without offsetting were shorter than the ones with 2mm offset. However, the forming pressure without offsetting was higher than the pressure with 2mm offset. Surface sink of the product without offsetting was observed below the tool probe. This implies that the probe restricts supplement of material volume to the die cavity directly below it, though it effectively extends the deformable material volume.
Abstract: Electro-Discharge Machining (EDM) is very popular for machining high-strength conductive materials for aerospace and automotive application. These machining involve a range of processing parameters. In order to optimize these for the best performance, a trade-off has to be decided for the responses achieved through machining. Conventional algorithms have long been replaced by advanced optimization algorithms. Performance of meta-heuristic algorithms in relation to traditional deterministic approaches for multi-modal, non-linear engineering problems is very promising in recent days. In this paper, a multi-objective optimization approach is applied using a population-based meta-heuristic algorithm called Passing Vehicle Search (PVS) for optimizing process parameters of various mathematical models formulated by different authors. Different approaches depending on case have been adopted for formulating the multi-objective PVS algorithm and pareto front is obtained for each case to extract the desired results. The performance of multi-objective PVS is compared with different intelligent computing models employed in prior studies and better results are shown in case of former. This approach can be extended to various mathematical models besides those covered in the paper to obtain better optimization results.
Abstract: Strip casting of Al-40%Sn-1%Cu, which is an aluminum alloy used for sliding bearings, was attempted using an unequal diameter twin roll caster. The conditions required to cast sound strips, including the roll speed, molten temperature, roll load, solidification length, melt head, and use of an upper plate, were investigated. The roll load required to make a stable strip surface was 0.01 kN/mm, and the porosity was minimum when the solidification time was less than 0.6 s. The solidification time was controlled by the roll speed and the solidification length. The casting temperature must be set below 670°C to properly solidify the molten metal, and the metal microstructure became finer as the melt head decreased.
Abstract: The Ti-6Al-4V alloy was nitrided at 950 °C for 8 h by heating under atmospheric nitrogen in order to improve its surface hardness and oxidation resistance. Nitrogen diffused into the Ti6Al4V alloy, and formed ~40 μm-thick coating consisting of TiN as the major phase and Ti2N as the minor one. Nitriding increased the surface microhardness through the strengthening effect of interstitial nitrogen and the formation of nitrides. Oxidation at 700 °C for 10 h formed a superficial TiO2 layer on the coating.
Abstract: Among the problems encountered when roll casting Al-405Sn-1%Cu, which is an aluminum alloy used for sliding plate bearings in large maritime diesel engines, are solidified chips embedded in the strip and scratch marks on the lower roll contact surface. In this study, three different improvement methods aimed at eliminating these particular defects—vibrating the side plates and back dam plate, adding a vibrating plate, and varying the casting conditions—are examined. Vibrating the side plates and dam plate was found to be effective for preventing these defects, while adding another vibrating plate was comparatively less effective. As for casting conditions, it was also determined that the occurrence of these defects could be reduced by increasing the roll speed, and that the molten metal casting temperature had little or no influence on defect formation.
Abstract: The aim of this work was to investigate whether the explosively welded metals are susceptible to hydrogen degradation. The materials described in this article are widely used nickel alloy Inconel C-276 and super duplex steel SAF 2507 as clad materials for their superior resistance to corrosive environment and low alloy steel P355NH as a base material. It was observed that at the explosive bonded interface between the base steel and the stainless steel some local melting zones are formed. It was found that the cathodic hydrogen charging causes changes in the microstructure of bonded materials and decreases the shear strength of bonds as well as the corrosion resistance of clads.
Abstract: Weaving the bobbin lace is a traditional activity from Peniche, a village situated in the west coast of Portugal. This activity is known like art for centuries. However, the traditional way of producing it has been kept as well as the works produced. The bobbin lace hasn’t accompanied the evolution of times nor does it risk innovation. This wrong perspective has led to the discredit of the product, leading the young generations to keep on producing it the way their ancestors have done it – weaving the lace both for home consumption and/or entertainment. In an interventionist methodology, we propose the use of new materials to replace the traditional use of cotton as far as weaving the bobbin lace is concerned as well as the creation of new products. These two parts getting together can and probably will give a new perspective of the traditional and lead to new consumptions and/or applicability to the bobbin lace. Innovation is the key word for doing it. The desire of getting to know the new and the different, recreated from the traditional, will arouse curiosity in the young generations.