t 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.
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.
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.
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.
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.
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.