Papers by Author: Fu Xing Yin

Abstract: The effect of ternary alloying elements on the oxygen Snoek-type relaxation in the Ti-24Nb-2X-1.7O alloys (X = Al, Sn, Cr, Mn, Fe) was investigated. The dipole shape factor (δλ) of the Snoek-type relaxation was figured out for each ternary alloy based on the measured damping peak with the variable temperature. The value of δλ in the Ti-Nb-Al alloy was the highest among the present ternary alloys. It was found that δλ increased with the decreasing lattice constant as well as the decreasing valence electron number per atom (e/a) and came to a maximum value when the e/a value was around 4.24, which defined the β phase boundary. Therefore, decreasing the lattice constants and the e/a value as largely as possible with alloying elements in the β-Ti alloys is one of the feasible ways to increase δλ and to design the high damping Ti alloys.

Abstract: Laminated materials and clad metals have received much attention in the industrial production due to the superior mechanical properties different from those in any of the constituent materials. Clad metal is a composite metal plate generally made by bonding a metal such as stainless steel plate to another metal such as carbon steel or low alloy steel plate. Clad metal not only has sufficient strength required of structural materials but provides other functions including resistance to heat and corrosion. As a result, the application of clad metals can significantly save precious alloying elements and reduce the cost. Therefore, clad metals have become an increasingly interesting topic in a variety of industrial fields. In this paper, fabrication technique and evaluation on mechanical properties of laminated metals have been briefly overviewed. In addition, the applications of laminated materials including clad metals are reviewed and the prospect of clad metals in the future is also described.

Abstract: Metallic closed cellular materials containing polymer were fabricated by the penetrating polymer into metal foam. The aluminum and stainless steel foams were selected for the metal foam and epoxy resin and polyurethane resin were selected for the penetrated polymer. The many kinds of mechanical properties of this material were measured. The results of the compressive tests show that these materials have different stress-strain curves among the specimens that containing different materials in the cells. Also, this metallic closed cellular materials containing polymer have higher compressive strength, higher Young’s modules, higher energy absorption and higher internal friction than that of metallic closed cellular material without any polymer.

Abstract: Tempering temperature dependence of the amount of the reversed austenite in the range of 570 oC to 680 oC was investigated by means of X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM) in a low carbon Fe-13%Cr-4%Ni-Mo (wt.%) martensitic stainless steel. It was found that the reversed austenite began to form at the tempered temperature slightly above the As temperature. As the tempered temperature increased, the amount of the reversed austenite changed little in the temperature range of 580-595 oC. Then, the amount of the reversed austenite increased sharply with the increased tempered temperature. When the tempered temperature increased to about 620 oC, the amount of the reversed austenite exhibited a peak. Afterward, it decreased quickly at the elevated tempered temperature. The microstructural evolvement of the reversed austenite at different tempering temperature was also observed by TEM.

Abstract: The evolution of crystallographic texture with equivalent strain, eq, was studied in low carbon steel bars fabricated using multi-pass warm caliber rolling. Finite element analysis was carried out to evaluate eq accumulated and strain components introduced with each pass through the rolled bars. The texture at characteristic deformation sites on the cross section in the bars was analyzed using the electron back-scattered diffraction method. Although the texture in the area around the center was dominated by a strong RD//<101>, in the other two areas, a RD//<101> texture was not produced. It is clarified that this difference results from three deformation modes during rolling. Consequently, the areas around the corners, where eq of over 5.7 is introduced, are filled with ultrafine ferrite grains of below 680 nm, and the texture in the areas is random regardless of the increase of eq.

Abstract: The Snoek relaxation, a specific point-defect induced anelastic relaxation phenomenon, is characteristic of an internal friction peak in bcc metals with interstitial solutes. Such internal friction mechanism has not been applied in the development of high damping alloy while grain boundary and twin boundary featured anelastic relaxations are applied in some high damping alloys. In this paper, the fundamental principles and experimental results concerning the Snoek relaxation are reviewed, and the feasibility to apply the Snoek relaxation mechanism into high damping alloys is discussed. Due to the peak-shape behavior in the Snoek relaxation type damping, composition design of a high damping alloys should takes temperature position, broadness and also peak height into account. Ti-Nb-O and Ti-V-Cr-O alloys are designed and fabricated by CCLM casting in our laboratory. It is conformed that the damping behaviors of the alloys are of Snoek relaxation type showing obvious frequency and temperature dependence. While the broadened damping peak caused by the substitutional solutes is advantage to improve the temperature stability of damping capacity, a large concentration of interstitial solute and texture control are required to improve the reduced damping capacity.

Abstract: Copper foils cold rolled up to 92% reduction exhibited a low intensity of the β-fiber texture and a high intensity of the cube and RD (rolling direction)-rotated cube components. After annealing, the recrystallization texture of the foils could be characterized by the mixture of the cube and the S components. An initial strong cube texture with a large grain size might remain a less developed rolling texture component, cube or RD-rotated cube, which would be the source of the S component in the recrystallization texture.

Abstract: This paper showed an example of the phenomena that a strong deformed texture does not change after the annealing process in steels. An Fe – 22%Cr – 3%Ni ferritic stainless steel was processed by bar rolling/swaging to a total strain of 4.4 at an ambient temperature, and its annealing behaviour was studied in a temperature range of 400 ~ 700oC. The deformed sample showed a grain size of 200nm, a fraction of high-angle boundary (HAB) of about 0.6, and a strong fiber texture of <110>{uvw}. This texture showed very little change after annealing which was characterised by the development of continuous recrystallization involving recovery processes and followed by a normal grain growth. On the other hand, by annealing a sample that was deformed to total strain of 2.0 containing rather fine grains (270nm) but without a large enough fraction of HAB (0.3), a discontinuous recrystallization took place, and its deformed texture changed considerably.

Abstract: Electron backscattered diffraction analysis has been used to investigate the effect of shear deformation on microstructural evolution of a Ni-30Fe alloy during hot deformation. The alloy was compressed by 50% or 75% in thickness at a strain rate of 1/s in a single pass at 1023K using a hot compression simulator. Three-dimensional finite element analysis was carried out to evaluate inhomogeneous strain distribution introduced in the specimens by the simulator. As the equivalent strain increased, the fraction of high angle grain boundaries (HAGBs) with misorientaions between 15o and 30o increased almost in the similar way regardless of the presence of shear strain. The fraction of HAGBs having misorientations in excess of 30o increased mainly at the expense of low angle grain boundaries with misorientations smaller than 15o. Such the expense occurred at much higher rate with shear strain than without shear strain. The shear component is effective to develop HAGBs in austenite grain interiors.

Abstract: M2052 alloy is a MnCu based high damping alloy that shows high damping capacity and the superior workability. In the present work, the microstructure and damping behavior of the alloy in different solidification cooling rates are investigated with directionally cast alloy plate. For the variation of solidification cooling rate in the range of 250~10K/s, the secondary dendrite arm spacing of the cast alloy changes from 4 to 18mm and grain size varies in the range of 100~200mm except the surface regions and center regions in the cast plate. As compared to the worked and heat treated alloy, the as-cast alloy shows a high temperature damping above the average phase transformation temperature of the alloy irrespective to the solidification cooling rate. On the other hand, a higher damping peak is observed in the cast alloy which is attributed much to the twin boundary damping, however, the magnitudes of the damping peak are found to be varied corresponding to the respective solidification conditions.