Metallurgy Technology and Materials V

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Authors: Toshio Haga, Kento Ikeda, Takafumi Nakano
Abstract: A 400 mm width of clad strip consisting of Al-40%Sn-1%Cu and 1070 aluminum alloy could be cast directly from molten metals at a speed of 10 m/min by an unequal diameter twin roll caster equipped with a scraper. An interface clearly existed between the two strips of the clad strip. As-cast clad strip could be cold rolled down to 1 mm without peeling at the interface. The as-cast clad strip could also be bent in the full contact condition without peeling at the interface.
Authors: Wen Wen Mao, Hua Lu, Chen Xiao Li, Hong Li
Abstract: Through thermal simulation experiment and SEM analysis, limestone dissolution in a steelmaking slag was studied. The results showed that the dissolution rate of limestone is 5.4 times greater than lime under the same conditions in slag, the dissolution rate of limestone in slag increases rapidly with the increase of stirring gas flux. The rapid dissolution of limestone in the slag can be explained on two sides. Limestone decomposition and dissolution happens simultaneously, the newly generated lime participates in slagging in its highest activity. On the other hand, CO2 from limestone decomposition not only strengthen the mixing strength of the molten pool, but also helps to remove the high melting point 2CaO·SiO2 product.
Authors: Bo Bo Meng, Quan An Li, Xiao Ya Chen
Abstract: The effects of heat treatment on microstructure and mechanical properties of Mg-9Gd-4Y-0.5Zr alloy were studied by XRD, OM, SEM and tensile testing machine. The results show that the alloy mainly consists of α-Mg matrix, Mg5Gd and Mg24Y5. Through solid solution and aging heat treatment process, the tensile strength, yield strength and elongation rate respectively achieves 263.1MPa, 235.2MPa and 3.11%.
Authors: Van Nhat Nguyen, Quoc Manh Nguyen, Dang Thi Huong Thao, Shyh Chour Huang
Abstract: Welding dissimilar materials has been widely applied in industries. Some of them are considered this as a strategy to develop their future technology products. Aluminum alloy and stainless steel have differences in physical, thermal, mechanical and metallurgic properties. However, selecting a suitable welding process and welding rods can solve this problem. This research aimed to investigate the T-joint welding between A6061 aluminum alloy and SUS304 stainless steel using new welding rods, Aluma-Steel by the Tungsten Inert Gas (TIG) welding process. The mechanical properties, the characteristics of microstructure, and component analysis of the welds have been investigated by the mechanical testing, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). As a result, the fracture occurred at the adjacent area between welding seam and A6061 alloys plate. The thermal cracking appeared at central welding-seam along the base metals if high welding current. A large amount of copper elements found in the welds due to using the new welding rod, Aluma-Steel rod.
Authors: Isamu Yoshida, Koshiro Mizobe, Katsuyuki Kida
Abstract: Martensitic high-carbon chromium bearing steel is used for rolling contact applications in various mechanical parts. Induction heating is one of heat treatment methods which take shorter time and lower energy compared with furnace heating. In the present work, we prepared induction-heated and furnace-tempered JIS SUJ2 bearing steel bar specimens. After rotating bending tests, we observed their fracture surfaces. It was found that the very large fisheye crack failures occurred and the crack size increased with increasing number of cycles to failure.
Authors: Da Yu Wang, Zhi Ming Du, Hong Juan Zhang, Li Hua Chen, Chang Shun Wang
Abstract: Mg-Zn-Zr-Y billets with different mass fraction of Y (wt%(Y)=0.2%、0.5%、1.0%、1.5%、2.0%) was prepared by permanent mold casting. The increase in Y content has shown grain refinement effects on the microstructure morphologies of Mg–Zn–Y–Zr alloys. When the content of Y achieves 1.0 wt%, the grain refinement effect of the Y is most obvious than any more contents of the Y content. In the test result of XRD, the type of precipitated phase in Mg-Zn-Zr-Y alloys is related to atomic ratio of Y/Zn. With content of Y increases, atomic ratio of Y/Zn increases,the precipitated phase in alloy is changed from Phase I to Phase W. Tensile strength and extension rate of alloy increase with the increasing of Y content; When Y content reaches 1.0%, mechanical property reaches maximum value.When content of Y exceeds 1.0%, with the increasing of Y content, mechanical property of alloy declines gradually.
Authors: Koshiro Mizobe, Kohei Egawa, Katsuyuki Kida
Abstract: There are two major heating methods used in industrial situations. One is furnace heating which is popular for mass production as it hardens the steel uniformly. The other is induction heating which is energy saving but hardens the steel unevenly. We developed a combined heat treatment method, furnace-induction heating (FIH), and observed the material structure using picral and nital etching.
Authors: Toshio Haga, Yoshihiro Tsunoji, Masashi Ueda, Akihiro Hirabaru
Abstract: Two types of side dams for a semi-continuous caster, a thin steel plate and a deformable fence, were developed and tested. The semi-continuous caster equipped with deformable side dam fences was found to be superior. The deformable side dam fences were set between the substrate and the roll. Molten metal was solidified by the lower substrate and the upper roll. A 10-mm-thick 1200 aluminum alloy plate was cast at 1 m/min. The deformable side dam fences were effective at providing plate reduction and ensuring a flat upper surface.
Authors: Guo Liang Zhu, Wei Wang, Rui Wang, Guo Xiang Wang, An Ping Dong, Dong Hong Wang, Zhi Wu Shi, Yu Long Li, Guo Dong Zhang
Abstract: GTD222 superalloy is a potential candidate for large-scale complex thin-walled castings with high temperature resistance in the next-generation aircraft engines, due to its excellent creep performance, good oxidation resistance and favorable weldability. The precision casting of GTD222 with a complex thin-wall structure was investigated in this work. The good quality of the final cast indicated that the optimized gating system obtained by numerical simulation was satisfying.

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