Papers by Keyword: Cross Rolling

Abstract: When studying a large number of steel grinding balls, which were destroyed in the course of delivery tests, an atypical structure of the balls’ central zone was detected. Namely, the presence of sites with the martensitic structure, while the main troostite structure was preserved. The balls were manufactured using the cross rolling technology. We studied the structure of the destroyed balls, as well as the composition and the structure of continuous cast billets, from which the balls were manufactured.

Abstract: The cold rolling and annealing texture formation has been investigated in electro deposited pure iron which has an extremely sharp and isotropic <111>//ND fiber. Regardless of cold rolling reduction, {111}<112> intensified texture is formed after cold rolling. Similar texture remains after recrystallization in 65% cold rolled material while {111}<110> type texture forms in 80% and 90% cold rolled ones. The recrystallized grains at the stage of 5% recrystallization have {111}<112> orientation in 65% cold rolled sheet, whereas {111}<110> is observed in 80% cold rolled one. From this aspect, it is considered that the nucleation orientation plays an important role in the recrystallization texture formation. In the meanwhile, the growth of the recrystallized nuclei is also supposed to affect the recrystallization texture formation. The nuclei with {111}<112> orientation in lightly cold rolled sheet are easier to consume the deformed matrix than they do in heavily cold rolled sheets because their frequency to encounter a deformed grain with nearly the same orientation is much smaller in lightly cold rolled specimen, which can result in a large mobility for growth. Cross cold rolling makes cold rolling texture rather homogeneous <111>//ND fiber, which gives rise to an almost homogeneous <111>//ND fiber after annealing.

Abstract: Cast magnesium alloys are resulting coarse grained structure and micro porosity. In order to improve the formability and ductility in magnesium alloy, it is planned to incorporate aluminum wires as reinforcement through extrusion. In the present paper, ZM21/Al macrocomposites were fabricated by direct co-extrusion process. The extrusion was carried at 450°C with the extrusion ratio of 25:1. Metallurgical bonding of ZM21 magnesium alloy and aluminum was studied with the help of optical metallography and hardness testing. It was observed a white interface layer (intermetallic) formed in between magnesium alloy and aluminum. The same was confirmed by hardness test and SEM-EDS test. The co-extruded macrocomposite was again processed with unidirectional rolling and cross rolling to improve the bonding and grain refinement of the alloy. The composite was rolled at 250°C for 75% reduction in thickness. The microstructure and hardness of the rolled composite were characterized.

Abstract: The microstructure evolution of the extruded Mg-9Li-1Al (LA91) during rolling was investigated taking account of effects of different routes including hot rolling, and cross rolling. The rolling parameters were suggested by thermal compression testing. As a result, the suggested rolling parameters were 250°C and 1.0s-1. Transverse hot rolling would bring a finer microstructure to the as-rolled LA91 sheet. With the enhancement of the rolling reduction during unidirectional hot rolling the α-Mg phase became granular or short rod-like from long strip-like. Transverse + longitudinal hot rolling would improve the microstructure and was a better cross rolling route by which the strength and the elongation of the cross rolled LA91 sheet reached 243MPa and 20% respectively. The over-aging existed in the cross rolled LA91 sheets.

Abstract: Ni-Cu alloy was developed by melting in a vacuum induction furnace using pure elements i.e., Ni, Cu, Fe, Si, Mn and Cr. Four heats of approximately 4 kg each were prepared. All the heats have been casted in an ingot of 10 cm long and 5 cm in diameter in vacuum. These ingots were hot forged at a temperature of 900°C to break down the cast dendritic structure. All forged plates were cut into two halve. One half was rolled in unidirectional while other was rolled in multiple directions (cross rolling). During rolling after every 25 % reduction, the cold rolled samples were annealed at a temperature of 900°C for one hour. Each plate was cold rolled to a final thickness of 0.345 mm. Half of these rolled plate produced either by cross rolling or unidirectional rolling were annealed at 900°C for 20 minutes. The mechanical properties of each rolled plate in cold reduction and in annealed were also measured. Unidirectional rolling and cross rolling has almost similar mechanical properties. The annealing of cross rolled and unidirectional rolling drastically reduced the yield strength. It was observed that the Ni-Cu alloy produced has slightly lower yield and ultimate tensile strength compared to the values reported in standards of Monel-400. However, it is within the acceptable range to be used for the various applications.

Abstract: In this study, two different cross rolling processes, which are effective rolling processes for a reduction of (0002) plane texture, are introduced. In the first cross rolling process, a sheet specimen is rotated around the rolling plane normal after each pass. In the second cross rolling process, the roll axis is tilted against the transverse direction (TD) in the rolling direction (RD) - TD plane. The two cross-rolling processed were carried out on a AZ31 alloy, and the press formability of cross-rolled sheets was compared with that of unidirectionally rolled sheets determined by Erichsen tests at 433 – 493 K. Both the cross-rolled specimens exhibited a high press formability, compared to an unidirectionally rolled alloy. The high press formability of the specimen by the first cross rolling was due to a reduction in (0002) texture intensity. The high press formability of the specimen by the second cross rolling was due to not only a reduction in (0002) texture intensity but also grain refinement.

Abstract: Deformation by rolling induces in general a strong crystallographic texture, hence an important material anisotropy. This is a reason why the cross-rolling is sometimes applied in order to symmetrize the crystallographic texture. Such an operation modifies also residual stresses. The goal of this study was to characterize residual stress and texture changes during simple and crossrolling in polycrystalline copper and ferritic steel. The obtained results show that important modification of the first order residual stresses occurs during cross-rolling, while the level of the second order ones is approximately constant. Experimental results were analysed using an elastoplastic deformation model.