ABSTRACT During production and heat treatments of aluminum alloys, numerous second phase particles form, which maximizes their mechanical properties. This work aimed to perform a correlation between Vickers hardness and X-ray diffraction results, when 7475-T7351 aluminum alloy processed by the cross rolling is subjected to annealing heat treatments (AHT) at 500 °C for different soaking times (15, 30 and 60 minutes) and for a soaking time of 15 minutes at different temperatures (200, 300 and 400 °C). The influence of the AHT (500 °C / 15 minutes) on the microstructure, via scanning and transmission electron microscopy, and tensile tests properties was also investigated. The results show evidence that the Vickers hardness decreased for AHT performed at 200 and 300 °C / 15 minutes and increase for greater temperatures and times. This behavior is probably due to modifications in the constituent/dispersoid particles and aluminum matrix observed from the X-ray analysis. Partial recrystallization and a coarsening of the precipitates was observed after the AHT at 500 °C / 60 minutes, whose brought harmful effects on the tensile mechanical properties.

ABSTRACT Samples of the Al 7075 naturally and artificially aged were processed by conventional and asymmetrical rolling with 5% of thickness reduction. The rolling processes were evaluated under room temperature and under warm condition (130°C). Mechanical properties were evaluated by uniaxial tensile and Vickers microhardness tests. Microstructure evolutions were followed by optical microscopy analysis. Naturally aged samples showed better yield strengthening under warm processing. Greater ultimate stress and ductility under room temperature processing was also noticed in naturally aged specimens. Artificially aged samples showed better mechanical properties under room temperature, softening under warm processing due to grain recovery process. Microhardness tests showed expected results for both rolling types, especially on asymmetrical rolling with the higher predictions were observed. Micrographs have shown no expressive grain changes or refinement although its flattening was observed. Precipitates were analyzed by EDS/SEM revealing the presence of MgZn2 and CuMgAl along the matrix that provides plastic strengthening.

The API 5L X70 steel is used in high-pressure gas transmission pipelines. Because of this, knowledge of presence of residual stress and their magnitude is important to assess the material integrity in service. For the pipeline manufacturing, tubes need to be curved which is often made using the hot induction bending process. This process can introduce different residual stress depending of tube position. For this research, in order to evaluate the residual stress, was used an API 5L X70 tube that was previously curved by hot induction process. Samples were taken from the extrados, intrados, neutral line and straight section of the curved tube. Residual stresses were studied by two conventional methods: X-Ray Diffraction (XRD) and Hole-Drilling, which are destructive and non-destructive methods, respectively, in order to assess their qualitative responses. Each of these methods presents particular methodologies in sample preparation and material analysis, but also they differ in factors such time consumption and cost of the analysis. The qualitative responses obtained by the two different methods were comparable and satisfactory and pointed out the existence of a compressive residual stress state in steel pipe.

Abstract The crystallographic texture developed during cold rolling and subsequent annealing of interstitial free sheet steels aims to increase conformability. For this, it is necessary to obtain partial α-fiber and continuous and homogeneous γ-fiber texture components. In this work, the influence of symmetric (SR) and asymmetric (AR) cold rolling on crystallographic texture and mechanical properties of an interstitial free steel (IF) was investigated. Symmetric cold rolling yields α- and γ-fibers, which are enhanced as deformation increases. Moreover, α-fiber weakening occurs due to recrystallizations, improving formability. The same fibers are produced by asymmetric cold rolling, but in this case, the γ-fiber is slightly shifted in psi, which is one of Euler angles second ROE's notation1,2, and more homogeneous than in symmetric rolling. The best mechanical properties were achieved by asymmetric cold rolling/annealed with about 80% deformation.

The effects of asymmetric and conventional deformations and annealing on the microstructure of non-grain-oriented (NGO) 3 wt% silicon steel were analyzed by x-ray diffraction, optical microscopy and magnetometry. The results suggest that pure asymmetric rolling tends to lessen magnetic losses. However, intermediate annealing resulted in lower planar anisotropy, which could be estimated from the magnetic anisotropy theory. In this work, it was shown that this theory is able to predict the J50 magnetic polarization values using crystallographic texture.

Dislocations are responsible for most aspects of plastic deformation in metals. In this work, the dislocation density, ρ, in brass was estimated after different deformation processes via line broadening of X-ray diffractograms using the Convolutional Multiple Whole Profile Program (CMWP) and by Transmission Electron Microscopy (TEM). In addition, we attempted to evaluate, on a global basis, the influence of crystallographic texture in ρ analysis, making sure that the results obtained by XRD could be trusted even in samples with moderate levels of texture. For this, we compared the ρ values for α brass samples (66% Cu and 34% Zn) with different levels of texture, one deformed by cold rolling and the other by equal channel angular extrusion (ECAE).The results suggest that using CMWP program it was possible to satisfactorily estimate the dislocation density in α brass. It also the was shown that the results by XRD and by TEM were self-consistent in two samples texturized to different degrees.