Mechanism of grain refinement of aluminium alloy in shear spinning under different deviation ratios

To investigate the grain refinement and its mechanism in shear spinning, microstructures of shear spun parts made by aluminium alloy under different deformation conditions, induced by different shear spinning deviation ratios, are studied. The results show that, after shear spinning, the microstructure is distributed symmetrically about a zone in sheet thickness defined as the neutral zone which is located between the inner surface and the middle plane of spun sheet thickness. Various deviation ratios in shear spinning can lead to grain refinement in different regions along thickness direction of the spun part. The microstructure characteristics indicate that the mechanism of grain refinement is due to the formation of deformation bands (DBs). It is observed that in DBs, parallel geometrically necessary boundaries (GNBs) formed by a zero deviation ratio and crossed GNBs formed by positive and negative deviation ratios are due to the different stress states induced by various deviation ratios in shear spinning. Due to the influence of grain refinement, micro hardness increases with the decreasing of the deviation ratio. The average value is increased by 16.04% under a negative deviation ratio compared to the initial micro hardness of the sheet

A review of process advancement of novel metal spinning

Metal spinning technology has seen a rapid development in recent years. Novel spinning processes, such as non-axisymmetrical spinning, non-circular cross-section spinning and tooth-shaped spinning, are being developed. This has challenged the limitation of traditional spinning technology being used for manufacturing axisymmetrical, circular cross-section, and uniform wall-thickness parts. In this paper, the classification of the traditional spinning processes is proposed based on the material deformation characteristics, the relative position between roller and blank, mandrel spinning and mandrel-free spinning, and temperature of the blank during spinning. The advancement of recently developed novel spinning processes and corresponding tool design and equipment development are reviewed. The classification of the novel spinning processes is proposed based on the relative position between the rotating axes, the geometry of cross-section and the variation of wall-thickness of the spun parts. The material deformation mechanism, processing failures and spun part defects of the aforementioned three groups of novel spinning processes are discussed by analyzing four representative spinning processes of industrial applications. Furthermore, other novel spinning processes and their classification as reported in the literature are summarized

The Precise Formula in a Sine Function Form of the norm of the Amplitude and the Necessary and Sufficient Phase Condition for Any Quantum Algorithm with Arbitrary Phase Rotations

In this paper we derived the precise formula in a sine function form of the norm of the amplitude in the desired state, and by means of he precise formula we presented the necessary and sufficient phase condition for any quantum algorithm with arbitrary phase rotations. We also showed that the phase condition: identical rotation angles, is a sufficient but not a necessary phase condition.Comment: 16 pages. Modified some English sentences and some proofs. Removed a table. Corrected the formula for kol on page 10. No figure

Elliptic flow of ϕ\phi meson and strange quark collectivity at RHIC

Based on A Multi-Phase Transport (AMPT) model, we have studied the elliptic flow $v_{2}$ of $\phi$ mesons from reconstructed $K^{+}K^{-}$ decay channel at the top Relativistic Heavy Ion Collider energy at Brookhaven National Laboratory. The dependences of $v_{2}$ on transverse momentum $p_T$ and collision centrality are presented and the rescattering effect of $\phi$ mesons in the hadronic phase is also investigated. The results show that experimental measurement of $v_{2}$ for $\phi$ mesons can retain the early collision information before $\phi$ decays and that the $\phi$ $v_2$ value obeys the constituent quark number scaling which has been observed for other mesons and baryons. Our study indicates that the $\phi$ $v_2$ mostly reflects partonic level collectivity developed during the early stage of the nucleus-nucleus collision and the strange and light up/down quarks have developed similar angular anistropy properties at the hadronization.Comment: 5 pages and 5 figures; accepted by Physical Review