Zakaria Boumerzoug

Texture and Evolution of Recrystallization in Low Carbon Steel Wire

The effect of cold wire drawing on texture of industrial low carbon steel wire was investigated. On the other hand, the mechanism of recrystallization of drawn-wire was studied during different isothermal annealing below 723 °C. The structural evolution of wire was studied by optical microscopy, SEM, EBSD and X-Ray diffraction. From this study, a fiber texture was observed in deformed wire. However, a recrystallization reaction occurs after critical temperature during annealing.

Temperature and Deformation Effects on the Recrystallization Microstructure and Texture of Wire Draw Steel

In this work, the effect of the deformation, caused by cold wire drawing, on the microstructure and the texture of low carbon steel wire (0.06 wt % C) is examined. The combined influence of the deformation level and the recrystallization temperature on the development of new grains is studied for all wires. Isothermal tests of annealing allow the determination of the critical temperature of recrystallization estimated above 450°C. The temperature effect is studied below the eutectoid level, at 500°C, 600°C and 680°C. The appearance of a homogeneous recrystallization is noted over the section of the wire. The recrystallized grains keep the same orientation as the deformed grains. The expansion of time of annealing lead to recrystallization in the ferritic grains accompanied by a spheroidization of the lamellar pearlite. The kinetics of recrystallization and spheroidization are accelerated by increasing of annealing temperature and the deformation level. The experimental techniques used in this study are: the Scanning Electron Microscope (SEM), the Electron Back Scattered Diffraction (EBSD), the X-ray diffraction and Vickers microhardness.

Study of Texture and Recrystallization in Wire Steel

The operation which allows reducing wire diameter is called wiredrawing. The wiredrawing principle is that of using the metal plasticity to reduce the wire diameter. Our study is based on wire steel containing 0.05 % carbon. The regular orientation of the grains (texture) caused by external stresses during the drawing process is observed. This texture causes a phenomenon of material consolidation. Two annealing temperatures were applied on deformed wires for modifying the structure and mechanical properties. The effects of drawing and thermal treatment on our material were studied by, scanning electron microscope, hardness measurements and X – ray diffraction.

Effect of the Long Natural Aging on the Precipitation Sequence in Al-Mg-Si Alloy

In this study, the effect of the long natural aging on the precipitation sequence of Al-Mg-Si alloy was investigated by differential scanning calorimetry and hardness examinations. This investigation revealed that the natural aging has a negative effect on the artificial aging. The reason behind the influence of natural aging on precipitation behavior of the Al-Mg-Si alloy is assumed to be the formation of clusters and G.P. zone during natural aging. The hardening mechanism during artificial aging was explained.

Dissimilar friction stir welding of Al-6061 to steel

Microstructure and mechanical properties of welded dissimilar materials by Friction Stir Welding (FSW) process depend mainly on several parameters such as tool rotational speed, feed rate, offset, and pin profile. In this study, the microstructure and strength properties of friction stir welded 6061-T6 aluminum alloy to ultra low carbon steel have been investigated using different traverse speeds, rotating speed and tool offset. Microstructures observations have been conducted by optical and scanning electron microscopy. The joint strength was evaluated on a tensile testing machine. X-ray diffraction has revealed the main phase inside the welded joint. The effect of traverse speed on the shear load of a joint has been found. We have found a relationship between microstructures and mechanical properties of welded joint.

The Natural Aging Effect on the Activation Energy of the Precipitation Processes in the Al-Mg-Si Alloy

The precipitation sequence of an Al-Mg-Si alloy depends on many parameters. In this study the natural aging effect on the activation energy of the precipitation sequence in the Al-Mg-Si alloy have been investigated by differential scanning calorimetry (DSC). The precipitation sequence of an Al-Mg-Si alloy has been established. The activation energy of the precipitation process was calculated using Kissinger model. The results obtained using this method showed a change in the activation energy for all precipitated phases. The activation energy of the metastable phases (β″ and β′) and the stable phase β formation in the Al-Mg-Si alloy aged at room temperature have been determined.

Texture in Welded Industrial Aluminum

In this investigation, grain orientation has been studied in an industrial aluminium Al99.5 which has been welded by TIG process. The optical microscopy and EBSD (Electron Back Scattered Diffraction) were the main techniques used to illustrate the effect of welding on grain orientation in fusion zone and in heat affected zone. Epitaxial growth has been observed in weld joint and texture of each zone has been determined. On the other hand, the effect of isothermal heat treatment at 400 °C on homogenization of welded joint has been also studied. It was shown that the cube orientation {001}<100> is the dominant texture component in welded joint before or after heat treatments.

X-Ray Analysis of Residual Stress in Weld Region of X70 Pipeline Steel

X-ray diffraction method has been used to analyze the residual stress distribution in weld region of an X70 pipeline steel before and after heat treatment. The welding process has been realized by industrial arc welding with circular weld seams. The effect of heat treatments on the level and the distribution of residual stresses were investigated. Stress distribution was characterized by relative high compressive stresses in weld seam just after welding. However, residual stress relaxation phenomenon was observed in weld region after heat treatments due to microstructure restoration and recrystalization. Optical microscope observation and Vickers hardness measurements were also realized as complementary microstructure characterization techniques.

Effect of Heat Treatments on Microstructure and Mechanical Properties of Low Carbon Steel Pipes Welded by Induction Process

In this work, the effect of isothermal heat treatments on microstructure evolution and mechanical properties after welding by induction of A37 pipeline steel have been studied by scanning electron microscopy, hardness measurements, and tensile tests. Microstructural evolution in welded joint was identified after isothermal annealing from 200 until 900 °C.

Residual Stress and Microstructures Characterization in Welded Al-Si- 12Cu Alloy

X-ray diffraction method has been used to analyze the residual stress distribution across the joint of Al-Si-12Cu alloy just after welding process. On the other hand, isothermal heat treatments have been applied in order to study the residual stress evolution in this material. Optical microscope observation and Vickers hardness measurement have been carried out as complementary microstructure techniques. The different zones of welded joint have been analyzed, where the fusion zone was characterized by dendritic structure and different to heat affected zone. We have found a softening phenomenon in welded joint after heat according to microhardness results.