Papers by Keyword: Warm Rolling

Abstract: Titanium alloys are used in a wide variety of aerospace, energy, industrial and biomedical applications, among other reasons, due to their superior properties. These properties are highly dependent of materials microstructure, i.e. texture, dislocation density and slip system activity. Therefore, in order to be able to design materials with certain properties it is crucial an understanding of the deformation process in terms of microstructural parameters. Microstructure evolution in warm rolled commercially pure titanium was investigated by means of X-ray diffraction and modeled with a crystal plasticity self-consistent scheme. Texture measurements and peak profile analysis were used to characterize the deformation texture and evaluate the relative activity of the various slips systems activated during the deformation process. The peak profile analysis data and the self-consistent predictions of texture evolution showed a good agreement with the experimental deformation texture evolution.

Abstract: Mg alloys are drawing a lot of attention and have been extensively studied. The major obstacle to the practical application of the alloys is the poor formability at room temperature, originating basically from the insufficient number of slip system. Development of a proper microstructure and/or texture is one promising solution to improve the formability. In the present work, after extrusion and full annealing, rolling at 300°C with different starting textures, the microstructures, texture developments and tensile properties of AZ31 Mg alloys are studied. After full annealing strong ∥ED fiber texture and weak + ∥ED fiber texture (c-axes in the radial direction) were developed. After rolling at 300°C many twins were formed, and the strong ∥ED fiber texture changed to ∥ND texture. Yield strength, tensile strength and elongation changed obviously depending on the microstructure and textures.

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: Based on analysis of steel production logistics and energy exchange process, some aspects about the steel warm rolling technology was introduced, including the principle, technical characteristics, application prospect, challenge, especially the significance on energy conservation and environmental protection. With the conclusion indication, warm rolling technology has vast application though facing many challenges in industrial production.The research fieldof warm rolling cover the plate flatness and gauge control, microstructure and property control, integration control of whole procedure conforming to each shape, corresponding equipment improving, and so on.

Abstract: The microstructure and macrotexture of ZK60 alloy sheet were investigated through OM and XRD, which were produced by twin roll casting and sequential warm rolling. Microstructure of twin roll cast ZK60 alloy changed from dendrite structure to fibrous structure with elongated grains and high density shear bands along the rolling direction after warm rolling process at different rolling parameters. The density of shear bands increased with the decreasing of the rolling temperature, or the increasing of per pass rolling reduction. Dynamic recrystallization could be found during the warm rolling process at and above 350oC, and many fine grains could be found in the shear band area. The warm rolled ZK60 alloy sheet exhibited strong (0001) basal pole texture. The formation of the shear bands tends to cause the basal pole tilt slightly to the transverse direction after warm rolling. The intensity of (0001) pole figure increased with the decreasing of rolling temperature, or the increasing of per pass rolling reduction.

Abstract: High shear strength of 25 kg/mm2 combined with a high plasticity makes Russian grade V65 aluminum alloys as potential candidate compared to AA2024 for riveting applications in aerospace industries. The lower content of magnesium over the AA 2024 alloy decreases the aging kinetics of this alloy because of the decreased vacancy concentration in the as-quenched alloy which in turn gives flexibility to carryout riveting operation even after 4 days after solution heat treat¬ment and natural aging at room temperature. This paper presents the processing and characterization of V65 aluminium alloy wires processed from hot and warm rolled rods. Mechanical properties of the wires have been evaluated in T6 and T4 tempers and correlated with microstructures. Detailed microstructural examination using optical microscopy and fractography of the tensile tested samples using scanning electron microscopy were carriedout.

Abstract: Warm rolled deformation is one of deformation technique to improve the strength of steels through the refining grain size of ferritic microstructure. In application, low carbon steel which used in structural industry need some protection against corrosion attack, cathodic protection is usually applied combining with coating. Cathodic protection creates reduction reaction which produces hydrogen, and the hydrogen atom may diffuse into the crystal lattice lead to the Hydrogen Induced Cracking. The present study is to observe the morphology of microstructure influenced by hydrogen charging as the source of hydrogen which attacks the steel surface, and observed by Optical Microscopy and Scanning Electron Microscopy. After warm rolling of 650oC and 35% deformation, ferrite grain size is smaller than bulk material and the hardness value increasing. After tensile test of hydrogen charged steel found the ductile fracture, it means the smaller the ferrite grains size, the resistance of hydrogen attack is increase.

Abstract: Magnesium alloys have attracted a great deal of attention and have been extensively studied, but there is still a major obstacle to their practical application, namely, their poor formability at room temperature, which basically originates from their insufficient number of slip systems. The development of a microstructure and/or texture that is more conducive to formability is one promising solution that could improve their formability. In the present work, the microstructures, textures, and tensile properties of AZ31 Mg alloys are studied following extrusion and full annealing and rolling at 100 and 300°C. After full annealing, a strong ∥ED fiber texture and a weak + ∥ED fiber texture (c-axes in the radial direction) were developed. After 40% rolling at 100°C, many deformed twins were observed and a relatively weak texture was developed. The basal poles were split and rotated about 20° to the rolling direction (RD). During 60% rolling at 300°C, dynamic recrystallization (DRX) took place and a strong ∥ND fiber texture was developed, and this had an influence on the alloys’ poor formability at room temperature.

Abstract: One-pass hot rolling in the ferrite region was conducted at higher temperatures, using various rolling temperatures and rolling reductions, with two types of ULC steels, 0.016% Nb and 0.023% Ti, and recrystallization behaviors immediately after hot rolling were investigated. The γ-fiber strength reached its maximum at around 50% rolling reduction at 1273K with the Nb-added steel and 1323K with the Ti-added steel. On the other hand, in high temperature rolling of the Ti-added steel, the γ-fiber did not develop, independent of rolling reduction. These changes corresponded to the recrystallized fraction, in that the strength of the γ-fiber decreased when recrystallization occurred immediately after rolling. New recrystallized-like grains were produced in the domain where distortions were particularly concentrated. Recrystallization seemed to be the result of various mechanisms, as some recrystallized grains were formed by a bulging mechanism, whilst others were surrounded by high angle grain boundaries.

Abstract: In this study, different combinations of cold and warm rolling routes are compared to determine the processing conditions that will best allow the production of nanostructured Ti-Ni shape memory alloy, while reducing mechanical damage from rolling and enhancing the material texture. The processed alloy is characterized using stress-free strain recovery and constrained stress recovery techniques, both in static and cyclic regimes. The results of such a comparative functional characterization of nanostructured Ti-Ni alloy obtained by five different manufacturing routes are discussed.