Browsing by Author "Ibrahim, R"

Now showing 1 - 12 of 12
  • No Thumbnail Available
    Item
    Friction stir forming to fabricate copper–tungsten composite
    (Elsevier B.V., 2015-03-01) Ahuja, Y; Ibrahim, R; Paradowska, AM; Riley, D
    Tungsten embedded composite of copper (C1100) was fabricated through probeless tool aided friction stir forming (FSF). The heat input conditions and forging were determined to be most effectively controlled by the tool rotation speed. A void-free and continuously bonded Cu–W interface was established at the parameter combination of 1200 rpm tool rotation speed with 100 mm min−1 traverse speed, 0.05 mm plunge and 3° tool tilt angle. The Cu–W interface was characterized via SEM and EDS analysis and was determined to be a purely mechanical interlock due to the absence of new phases. Microstructure of the friction stir formed copper near the interface was examined by optical microscopy. Mechanical properties of the processed copper were investigated by Vickers indentation and shear punch tests, and they showed good correlation with the microstructure. Grain refinement induced work hardening was observed in the copper close to the interface. Cu–W interface remained intact during the shear punch testing and failure occurred in the grain coarsened region of the copper 1 mm away from the interface. The bond strength of the Cu–W mechanical interlock fabricated by FSF was determined to be 130 MPa. © 2014 Elsevier B.V.
  • Thumbnail Image
    Item
    Industrial application experiments on the neutron imaging instrument DINGO
    (Elsevier, 2017-01-01) Garbe, U; Ahuja, Y; Ibrahim, R; Li, HJ; Aldridge, LP; Salvemini, F; Paradowska, AM
    The new neutron radiography / tomography / imaging instrument DINGO is operational since October 2014 to support the area of neutron imaging research at ANSTO. The instrument is designed for a diverse community in areas like defense, industrial, cultural heritage and archaeology applications. In the field of industrial application it provides a useful tool for studying cracking and defects in concrete or other structural material. Since being operational we gathered experience with industrial applications and commercial customers demanding beam time on DINGO. The instrument is a high flux facility with is 5.3 × 107 [n/(cm2s)] (confirmed by gold foil activation) for an L/D of approximately 500 at HB-2. A special feature of DINGO is the in-pile collimator position in front of the main shutter at HB-2. The collimator offers two pinholes with a possible L/D of 500 and 1000. A secondary collimator separates the two beams by blocking one and positions another aperture for the other beam. The neutron beam size can be adjusted to the sample size from 50 × 50 mm2 to 200 × 200 mm2 with a resulting pixel size from 27 μm to ∼100 μm. The whole instrument operates in two different positions, one for high resolution and one for high speed. We would like to present our first experience with commercial customers, scientific proposals with industrial applications and how to be customer ready. © 2017 The Author(s). Published by Elsevier B.V.
  • Thumbnail Image
    Item
    Investigating the effect of pre-heating on the magnitude of residual stresses in aluminothermic rail welds using neutron diffraction
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2013-12-02) Khodabakhshi, B; Paradowska, AM; Mutton, PJ; Ibrahim, R
    Aluminothermic rail welding is an in-track process which continuously welds rail tracks on site. This weld has a high rate of failure due to its cast structure and variable quality. The existence of residual stresses which are developed during the casting process is one of the main factors affecting the formation and propagation of the cracks in the foot and head of the rail. Magnitude of these stresses depends on the welding parameters such as preheating. Hence, it is desirable to determine the correlation between the residual stresses and welding parameters in order to decrease the residual stresses and increase the life span of these welds. In this paper, the effect of pre-heating on the magnitude of residual stresses in the foot and head of the rail weld is investigated using strain scanner Kowari at ANSTO. Previously, residual stresses in these welds have been measured using neutron diffraction. However, this is the first time that measurements are conducted for a full sample non-destructively. The results indicated that the magnitude of residual stresses decreases by optimizing the preheat procedure, and this is quite promising and can assist the railway industry to improve the integrity of the rail welds in future.
  • No Thumbnail Available
    Item
    Investigation of reference samples for residual strain measurements in a welded specimen by neutron and synchrotron x-ray diffraction
    (Elsevier, 2006-11-15) Paradowska, AM; Finlayson, TR; Price, JWH; Ibrahim, R; Steuwer, A; Ripley, MI
    In this research, both neutron and synchrotron X-ray diffraction techniques have been used to investigate variations in measured d spacing in two reference samples. The reference “stress-free” samples, a set of cubes and a comb sample, were produced using electro-discharge machining (EDM) to obtain a macro-strain-relieved condition. It is shown that there is a variation in microstructure across the parent metal, heat-affected zone (HAZ) and weld metal. A study of the issues in using the cubes and comb sample to provide reference d0 values for the measurement of residual stress in welding is presented. © 2006 Elsevier B.V.
  • Thumbnail Image
    Item
    Investigation of residual stress in multi-bead on plates
    (Australian Institute of Physics, 2006-02-07) Paradowska, AM; Price, JWH; Finlayson, TR; Ibrahim, R; Belvins, R; Ripley, MI
    The neutron diffraction technique is used to investigate and compare the residual stress characteristics in fully restrained samples with different numbers of beads. The aim of the research was to characterize the residual stress distribution which arises in a welded component with increasing the number of passes or beads. These results support the concept that welding integrity can be increased as additional layers of welding are added
  • No Thumbnail Available
    Item
    Investigation of strain-free reference for residual strain measurements in a weldments by neutron and synchrotron diffraction
    (Elsevier B. V., 2005-11-27) Paradowska, AM; Finlayson, TR; Price, JWH; Ibrahim, R; Steuwer, A; Ripley, MI
    The measurement of residual strain using diffraction techniques relies on the determination of a change in lattice parameter relative to reference or 'strain free' lattice parameter. Elucidating a relevant reference lattice parameter is the most important part of any diffraction-based, residual strain experiment. In this research, neutron and synchrotron diffraction techniques have been used to investigate the strain distribution in strain reference samples used to establish the residual stresses due to welding. It is shown that there is a variation in measured diffraction angles along the length of the weld, in particular for a parent metal, heat-affected zone (HAZ) and weld metal. The stress-free samples, cuboid and a comb sample, were produced A study of the issues in using the cubes and comb sample, were produced using electro-discharge maching (EDM) to obtain a macro-strain relieved condition and reveal information about microstructural and intergranular strain variations, residual stress in welding is presented. A study is presented of the application of a strain-free cuboid and a comb sample in the flux-cored arc welding (FCAW) process
  • No Thumbnail Available
    Item
    Measurement of residual stresses in aluminothermic rail welds using neutron diffraction technique
    (Scientific.Net, 2014-02-01) Khodabakhshi, B; Paradowska, AM; Ibrahim, R; Mutton, PJ
    It is understood that residual stresses in aluminothermic rail welds play an important role in the fatigue behaviour of the welds. Measuring the residual stresses in the critical areas and finding the correlation between these stresses and welding parameters can be useful in order to alter the welding procedure and improve the fatigue performance of these welds. In this paper, residual stresses in the foot of the rail weld were measured using neutron diffraction and the preliminary results are presented. © 2021 by Trans Tech Publications Ltd.
  • Thumbnail Image
    Item
    Measurement of residual stresses in aluminothermic rail welds using neutron diffraction technique
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2012-11-09) Khodabakhshi, B; Mutton, PJ; Paradowska, AM; Ibrahim, R
    Aluminothermic welding is widely used as an in-track process to continuously weld rail tracks on site. This process provides increased flexibility compared to the use of mobile Flashbutt welding equipment; however the cast structure and variable quality results in increased failure rates. One of these failure modes is straight break which initiates at the edge of the weld collar in the lower head and upper foot sections. In order to examine the fatigue behavior of the weld by using multi-axle fatigue analysis, residual stresses in critical areas need to be investigated. In this paper, we are showing preliminary neutron diffraction residual stress measurements in the critical region of the rail foot area at two sides of the weld collar, which have been determined using strain scanner Kowari at ANSTO. The result shows high longitudinal stresses in the location which is prone to the failure approximately 50 mm away from the weld's toe. The pros and cons of the measurement technique in relation to the weld rails components will be discussed and future research plans will be presented.
  • No Thumbnail Available
    Item
    Probeless tool aided friction stir welding as a fabrication technique for tungsten embedded mechanical composite of copper
    (The American Society of Mechanical Engineers, 2014-11-18) Ahuja, Y; Ibrahim, R; Paradowska, AM; Riley, DP
    Friction stir welding (FSW) is a relatively new solid state metallurgical joining technique. It flourishes on the simple principle of utilising frictional heat by the stirring motion of a non-consumable rotating tool to create the seam. Feasibility of FSW aided by a newly designed probeless tool was investigated for fabricating copper-tungsten mechanical composite. The most effective parameter combination was determined by conducting a parametric study of the probeless tool aided FSW copper. Strength of the mechanical composite fabricated at this condition was evaluated through punch shear testing. Punch shear testing established that the friction stir welded interface of the copper-tungsten composite was 87% as strong as the base metal (i.e. copper). Advantages of the designed technique have been summarised. © 2014 ASME
  • No Thumbnail Available
    Item
    Residual stress distribution in steel butt welds measured using neutron and synchrotron diffraction
    (Institute of Physics, 2009-03-25) Paradowska, AM; Price, JWH; Finlayson, TR; Lienert, U; Walls, P; Ibrahim, R
    70 keV synchrotron radiation and thermal neutrons have been employed to investigate the residual stress characteristics in a fully restrained, steel, butt weld. The focus is on the values of the subsurface and through-thickness strain/stress variation in the middle of the weld. The advantages and limitations of the techniques have been addressed, in relation to the gauge volume, the stress-free reference sample and positioning. The measurement of residual stress around the weld achieved in this work significantly improves the resolution at which residual stress in welded components has been determined. © 2009, Institute of Physics
  • No Thumbnail Available
    Item
    Residual stress measurements by neutron diffraction in multi-bead welding
    (Elsevier, 2006-11-15) Paradowska, AM; Price, JWH; Ibrahim, R; Finlayson, TR; Blevins, RJ; Ripley, MI
    The neutron diffraction technique is used to investigate and compare the residual stress characteristics in fully restrained samples with different numbers of beads. The aim of the research was to characterize the residual stress distribution which arises in a welded component with increasing the number of passes or beads. The resolution of the measurements carried out in this work achieves a new level of detail and reveals significant features of the residual stress pattern in multi-bead welding. The findings have important consequences for the design of welding procedures, demonstrating the effects of placing new beads on prior welding. © 2006 Elsevier B.V.
  • No Thumbnail Available
    Item
    Residual stress measurements by neutron diffraction in welded steel structures
    (The Bragg Institute, Australian Nuclear Science and Technology Organisation, 2005-11-27) Paradowska, AM; Price, JWH; Finlayson, TR; Ibrahim, R; Blevins, RJ; Ripley, MI
    In this paper the neutron diffraction technique is used to investigate and compare the residual stress characteristics due to various restraints for a single bead and in fully restrained samples with different numbers of beads. The aim of the research was to characterize the residual stress distribution which arises in a welded component with increasing the number of passes. The care and resolution of the measurements carried out in this work achieves a new level of detail and reveals significant features of the residual stress pattern in multi-bead welding. The findings have important consequences for the design of welding procedures, and fitness-for-purpose assessments. © The Authors