Jan Kuśnierz

Texture of Al-Cu Alloys Deformed by ECAP

Materials of ultra-fine grained microstructure (sub-micrometer grain size) exhibit large strength, hardness and ductility and also the increased toughness in comparison with conventional coarse-grained ones. In these materials also the super-plastic flow at lower temperatures is observed. This behaviour may be interesting when aluminium alloys like AlCuZr, used in superplastic forming, are considered. In the paper, the methods of preparing such materials by equal-channel angular pressing (ECAP) is proposed and the texture analysis, based on neutron diffraction pole figure measurements and calculated orientation distribution function of two alloys AlCu4SiMn and AlCu5AgMgZr is discussed. The influence of short time recrystallization is discussed in relation with TEM and SEM observations.

The Effect of Shear Bands on the Evolution of Rolling and Recrystallization Texture in Cold-Rolled Direct Chill Cast Strips of Brass

The texture of cold rolled and annealed cast strips of 70/30 brass was investigated. A delayed development of the main {110} component of brass type rolling texture was attributed to the intense deformation twinning which is associated with appearance of the strong {211} texture component at 50% reduction. The predominace of the {011} texture component in the range of 70%-90% reductions was related to the extensive shear banding. As for the rolling textures, the delay in development of the {236} component of brass type recrystallization texture was found.

Angular Extrusion of Double-Metal Ingot

Relatively high mechanical strength and simultaneously good plasticity of a crystalline material are determined by the state of its internal structure, preferably nano- or ultra-fine grained one. To achieve the above combination of properties, various manners of plastic deformation and heat treatment are applied in practice. One of the most effective processes in this field is severely plastic deformation, e.g. by the method of equal angular channel pressing (ECAP). During the ECAP, favourable effects of grain fragmentation and the formation of specific orientation relations can be attenuated by the process of structure recovery, especially, when the real temperature of angular extrusion is elevated for physical or technological reasons. An attempt to modify the ECAP technology was considered, to avoid the unfavourable temperature effects and to increase at the same time the efficiency of manufacturing the ultra-fine structure of material. Extrusion of dual-material (AZ31 + Al) ingot was performed at room temperature. As it seems, the well known difficulties with plastic deformation of materials with hexagonal lattice symmetry, like AZ31 alloy, have been decreased. Both experimental and methodological aspects of the angular extrusion of the dual-material ingot and chosen microstructure characteristics (texture, stress, morphology) are presented. On the basis of the suggested modification, the text discusses an explanation of physical origins of the microstructure evolution in the investigated material revealed by experiments.

Rolling Texture of ECAP Processed Al and Cu

The orientation distribution functions of conventionally prepared and pre-deformed copper and aluminium up to ı = 7.2 by the Equal-Channel Angular Pressing mode C, and then cold rolled up to 95 % area reduction have been analyzed in the paper. The rolling texture of conventionally prepared coarse-grained copper was characterized by {011}<3-11> component, whereas that of small-grained copper was characterized by {351}<1-12>. However, both components were present in copper pre-deformed up to ı = 7.2 by ECAP technique. In the ECAP pre-deformed aluminium the perfecting of the {113}<12-1> component of the rolling texture followed the increase of deformation. The texture has been discussed in relation with mechanical properties and structure observations.

Evolution of Texture in ARB Processing of Al 99.8

The accumulative roll-bonding (ARB) process, invented a few years ago, is a promising mode for introducing severe plastic deformation into industrial practice. The ARB process consists in rolling of the pack of two sheets up to 50 %. Then, the rolled material is sectioned into two halves, stacked and the procedure of roll-bonding is repeated. The orientation distribution of ARB processed Al 98 % up to e ~ 12 is analyzed in the paper. The evolution of crystallographic texture has been discussed in relation with changes of mechanical properties and structure.

Strain Induced Fracture in Textured Al-Li Alloys

Metallurgical as well as geometrical factors may be responsible for severe in-plane anisotropy of mechanical properties and abnormal fracture behaviour of aluminium-lithium alloys sheets. The crystallographical texture is considered to explain the observed anisotopy of tensile strength and the coefficient anisotropy (r-value). Morphology of the grain is additionally taken into account when discussing the fracture behaviour.