Papers by Keyword: Deformation Texture

Abstract: Unalloyed titanium was rolled with 20% reduction in each pass at 293 K using a cross rolling mill, where the upper and lower rolling axes were skewed each other at an angle of 0, 5 or 10 degree with parallel position. Multi-pass flat-rolling was carried out without any lubricants up to the true strain of 1, where two kinds of rolling directions such as tandem (uni-direction for all passes) and reverse (opposite direction in every passes) were adopted. The strain of specimens was increased proportionally as higher passes regardless of the rolling conditions. The transverse direction (TD) split deformation texture in titanium was generally developed under the cross angle of 0 degree. In the present strips of tandem, a main orientation was identified as (-12-18)[10-10]. In the case of tandem with the cross angle of 5 degree, a fiber texture was developed along (-12-18). That is the reason why a rotation in the rolling direction (RD) was overlapped. In the case of reverse with the cross angle of 5 degree, the main orientation was separated into [10-10] and [2-311] that were corresponded to TD and RD splits, respectively.

Abstract: B₄C/Al composite was a promising neutron absorb material. In this work, B₄C/Al composite sheets were asymmetrically rolled and annealed. The asymmetric (ASR) condition was introduced by applying mismatched roll diameters with diameter ratios of 1.1, 1.2 and 1.3, respectively., while the symmetric rolling (SR) was used as the control experiment. Mechanical properties and microstructures of the composite were tested after cold rolling and annealing. Results showed that: ASR with small diameter ratio decreased the texture volume fraction in the B₄C/Al composite, but when diameter ratio of ASR reached 1.3 new slip systems were actuated and the texture volume fraction started to increase. The average grain size of the aluminium matrix was smaller after ASR, and it decreased with the increasing diameter ratio. The hardness of B₄C/Al composite after ASR was about 40% higher than the one rolled by symmetric rolling, proved that ASR is a promising way to enhance the properties of B₄C/Al composite.

Abstract: The textures of cold-rolled AISI 304 austenitic steel were the object of the investigations. The austenite steel was deformed by cold-rolling to 20, 40 and 70% reduction. A significant amount of martensite, formed due to the strain induced (γ®a’) transformation, was detected in the deformed structure by applying magnetic and X-ray diffraction methods. Texture analysis was performed on the basis of the orientation distribution functions (ODFs) calculated from the experimental pole figures. The texture measurements of both phases were conducted from the center layers of the cold-rolled strip. In the case of metastable austenite AISI 304 steel the texture development was very complex because three processes were proceded simultaneously during the cold-rolling, namely: plastic deformation of the austenitic g-phase, strain induced phase transformation γ®a’ and deformation of the formed a’-martensite. These processes resulted in the presence of two phases in the structure of the steel with a definite crystallographic relationship and orientation changes of both phases with increasing of the deformation. Thus, the resultant deformation texture of the investigated steels is described by the austenite and martensite texture components. The rolling texture of γ-phase describes mainly orientations from the fiber α =<110>║ND and the major components of the martensite deformation texture are orientations from the fibers α₁=<110>║RD and γ ={111}║ND.

Abstract: The silicon steel was rolled to 95% reduction at 20°C, 400°C and 600°C, and subsequently annealed at different temperatures to obtain complete recrystallization microstructure without appreciable grain growth. The effects of rolling temperature on through-thickness deformation and recrystallization textures were investigated by ODF analysis. The deformation textures are all composed of α- and γ-fiber, whereas α-fiber and {111}﹤110﹥ decrease and {111}﹤112﹥ increases with the increasing rolling temperature. Through-thickness recrystallization texture varied significantly, a strong partial γ-fiber spreading from {111}﹤112﹥ or {554}﹤225﹥ to {111}﹤134﹥ and {114}﹤481﹥ are developed in steel sheet rolled at 20°C and 400°C, while a dominated η-fiber peaked at {310}﹤001﹥ is formed between surface and quarter thickness in steel sheet rolled at 600°C. The different recrystallization textures can be ascribed to the profuse shear band at 600°C compared with the microstructures at 20°C and 400°C.

Abstract: The method was developed for quantitative estimation of inputs to plastic deformation of crystallographic and non-crystallographic modes of slip by data of X-ray texture measurements. The texture analysis allows to split material into fractions, deformed by predominant operation of crystallographic and non-crystallographic mechanisms, differing in final orientations of grains. Whereas texture maxima in pole figures correspond to grains, deformed by means of crystallographic slip and having predictable final orientations, texture minima are formed by grains, whose deformation does not submit to crystallographic regularities and therefore their orientations are deflected from stable positions or even prove to be arbitrary. These effects are demonstrated as applied to semi-products from Zr-based alloys, subjected to the deformation treatment at temperatures of the (α+β)-region of Zr-Nb phase diagram.

Abstract: At the entrance temperature of 300°C, the effect of mill temperature on the texture and microstructure evolution was worked to 85/15 α-brass by two rollings with mill temperatures calibrated as 28°C for one rolling and 55°C for another, in which TEM was employed to reveal the microstructures, and ODF to represent the related textures. From the experiment evidence, a detailed discussion was made and led to a conclusion: in current rolling, with recovery, mill temperature influences the rolling texture and microstructure development through chilling and the working temperature induced deformation mechanisms change, the former one affecting B intensities, by contrast, the latter one leading to a texture transition.

Abstract: Abstract. Experimental evidences of regular differences in the substructure condition of grains depending on their position within texture maxima are demonstrated. Analysis of generalized pole figures (GPF) for rolled metal materials shows that the strain hardening intensifies as an angular distance of grains from the texture maximum centre increases. The mechanisms of this phenomenon are considered using the concepts of the texture formation theory.

Abstract: Texture, structure, and magnetic and mechanical properties of thin tape substrates fabricated of ternary nickel alloys with chromium, tungsten, molybdenum, and vanadium have been investigated. It has been shown that in Ni_93.8Cr_4.0Mo_2.2, Ni_88.5Cr_6.2V_5.3 and Ni_88.4Cr_9.2W2.4 alloys a sharp cube texture can form, which is stable up to high annealing temperatures. In the Ni_87.6Cr_8.0Mo_4.4 alloy, other weak orientations are present, along with the strong cube component. The possibility of obtaining a sharp cube texture after primary recrystallization is controlled by the quantitative relationship between the texture components in a cold-rolled tape, which is determined by the method of orientation-distribution functions. Three alloys studied are non-magnetic at 77 K.

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.

Abstract: A 2-dimensional vertex dynamics simulation is applied to the annealing behaviour of deformed Aluminium single crystals having different orientations. It is observed in experiments that deformed single crystals of different orientations - typically the common rolling textures like Goss (110)[001], Brass (110)[1-12], Cube (001)[100] – exhibit remarkably different rates of recovery. It is suggested that this difference arises from the deformation microstructures, with sub-grain boundaries of various misorientation values. The sub-grain boundary mobilities and energies, being strong functions of the boundary misorientation, thus affect the recovery rates. This effect is illustrated using vertex dynamics simulation on the same orientations and schematic deformation substructures as above. Good agreement is obtained for the orientation dependency of recovery.