Textures of Materials - ICOTOM 16

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Authors: Bevis Hutchinson
Abstract: The cube texture in rolled and annealed fcc metals and alloys has long fascinated metallurgists because of its high symmetry and extreme sharpness. This paper demonstrates and analyses the texture perfection that is developed in a copper sample. Reasons that have been advanced to explain the development of the texture during recrystallisation and grain growth are discussed. Orientation selectivity is favoured during growth but more particularly in the nucleation stage. Especial attention is paid to the rapid recovery which cube oriented crystals undergo on heating after plane strain deformation and which is the basis for its uniquely preferential nucleation. Various metallurgical factors are known to affect the strength of the cube texture in practice and explanations for some of these are presented.
Authors: Brent L. Adams, David T. Fullwood, J.A. Basinger, T. Hardin
Abstract: Significant advances are reported in the application of HR-EBSD to the imaging of the dislocation structure of polycrystalline materials. The central assumption of the method is the compatibility of the total displacement field, which relates the (Nye) dislocation tensor to the (partially measurable) curl of the elastic displacement field. Two key challenges must be addressed, including: a) the fundamental limitation imposed by the electron-opacity of typical materials, which limits the measurement of gradients in the displacement field in the direction normal to the sample surface; and b) the inability of HR-EBSD to recover the spherical (elastic) distortions of the lattice. This second challenge can be overcome if a traction free boundary condition is applied. It is illustrated that consideration of the familiar stress equilibrium relations gives additional information, which may enable estimates of the missing components of the Nye tensor. An example of application of HR-EBSD to a Mg-Ce sample is presented.
Authors: Jürgen Hirsch
Abstract: Textures and related anisotropy effects which occur in certain industrial processes are presented for as-cast, deformed and annealed (recrystallized) Aluminium alloys and products. They are analyzed in detail and discussed based on their formation mechanisms, which are growth selection during solidification and the formation of new grains during casting and recrystallization, glide on selected slip planes during plastic deformation and oriented nucleation and oriented growth of new grains during recrystallization. Alloy composition and constitution that control microstructure evolution during processing (e.g. casting, extrusion, hot and cold rolling, annealing) determine the material quality and product performance.In these cases industrial processing of Aluminium alloys is specifically designed to control textures to achieve superior anisotropic properties and so better meet special product requirements. Examples are given for resulting properties, like strength and formability / anisotropy effects in packaging and automotive sheet applications. Other examples are given for the etching behaviour of high purity Aluminium capacitor foil and strength anisotropy of age hardened extrusions for aerospace applications.
Authors: Paul van Houtte, Jerzy Gawad, Philip Eyckens, Albert van Bael, Giovanni Samaey, Dirk Roose
Abstract: Cup drawing of sheet material (carbon steel DC06 and aluminium alloy AA3103-O) is simulated using a Finite Element (FE) method configured as a hierarchical multi-scale model. It performs a two-way simulation of the interactions between the metal flow and the crystallographic textures of the polycrystalline material. In this, the evolution of the deformation textures is simulated by the Taylor and ALAMEL models, and this in every integration point of the FE mesh. The resulting textures have been compared with experimentally measured ones at different positions within the work-piece. An anisotropic constitutive model is used based on the Facet model identified from the current texture in every location by means of the Taylor and/or ALAMEL model. The updating procedure has been highly optimized. Simulated and experimental results (cup profiles, deformation textures) are compared. The effect of texture updating is assessed.
Authors: Ranjit Kumar Ray, P. Ghosh
Abstract: Interstitial free high strength steels (IFHS) are widely used in the automobile sector due to their high strength and excellent formability. However, these properties of IFHS steels are very much dependent on the processing parameters, like hot rolling, cold rolling and annealing. The composition and processing parameters influence the chemistry and morphology of the precipitates formed in these steels, which in turn control the texture and thus the deep-drawability. This review will briefly summarize the findings of the ongoing research in this area. An attempt will also be made to elucidate the correlation of precipitation behavior and texture formation (and thus formability) in these steels.
Authors: Hiroyuki Kokawa, Yutaka S. Sato, Sergey Mironov
Abstract: The principal features of material flow during friction stir welding (FSW) were illustrated via textural measurements in magnesium alloys. The straining state in the stir zone was demonstrated to be close to the simple-shear deformation with the shear plane/direction aligned with the local surface of the welding tool. Due to the unique nature of FSW process as well as specific character of the welding tool geometry, texture distribution in the stir zone was shown to be inherently inhomogeneous. The impact of this effect on mechanical properties is briefly considered.
Authors: Jae Hyung Cho, Sang Su Jeong, Suk Bong Kang
Abstract: Evolution of texture and microstructure during deep drawing of ZK60 wrought magnesium alloys were investigated using EBSD (electron backscatter diffraction). ZK60 (Mg-5.5Zn-0.6Zr) alloys were prepared through both direct chill casting (DC) and twin-roll strip casting (TRC). Deep drawing tests were carried out under various working temperature and drawing speeds. The diameters of the sheets and punch were 74 mm and 37 mm, and overall limit drawing ratio was 2. Texture and microstructure evolution was examined with various working condition. The DC samples had larger grains than TRC samples, and thus more twins were observed in the DC samples.
Authors: Dinakar Sagapuram, Mert Efe, Wilfredo Moscoso, Srinivasan Chandrasekar, Kevin P. Trumble
Abstract: Deformation microstructure and texture in Mg-AZ31B bulk strips processed through extrusion-machining were studied as a function of deformation temperature. At warm deformation temperatures (~200°C), cold-worked type microstructures with predominant tilted basal texture were observed. With increase in temperature, grain structure sharply transformed into equiaxed type with predominant in-plane basal texture. This sharp transition was found to be consistent with change in temperature dependent dynamic recrystallization mechanism from continuous to discontinuous type.
Authors: Chang Shu He, Dong Wang, Wei Ping Tong, Gang Zhao, Xiang Zhao, Liang Zuo
Abstract: 4-mm thick Al-12.7Si-0.7Mg alloy plates were cut from the hot extrusion profiles. A butt-welding joint was made by friction stir welding (FSW). Optical microscopy and SEM-EBSD analysis were employed to examine the microstructure and texture evolution in the stir zone of the joint. This work provides basic information for microstructure and microtexture characteristics in the stir zone after FSW for this novel wrought Al-Si alloy.

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