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  • 1
    Electronic Resource
    Electronic Resource
    PO Box 1354, 9600 Garsington Road, Oxford OX4 2XG, UK. : Blackwell Science Ltd
    Fatigue & fracture of engineering materials & structures 28 (2005), S. 0 
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Friction stir (FS) welding is a relatively new solid-state welding process that offers high levels of joint performance with minimal preparation and little post-weld dressing. The high levels of plastic work induced in the weld zone produce a very fine grain size in the stirred region of the weld (e.g. the nugget), while the low heat input limits residual stresses to a low fraction of the proof strength of the weld metal. These effects are generally beneficial to weld dynamic performance. The peculiar thermomechanical history in the FS weld region leads, however, to particular defects with some unusual effects on crack path, whose occurrence depends partly on crack speed, or growth rate. This paper presents observations regarding specific influences of the FS welding process on crack paths and dynamic performance for 5083-H321 and 5383-H321 aluminium alloys, and proposes an explanation for the observations in terms of the weld microstructures and thermomechanical history. The insights presented in this paper can be used to inform optimisation of the weld process parameters, through on-line feedback and control of tool geometry, force footprint, torque and temperature.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    PO Box 1354, 9600 Garsington Road, Oxford OX4 2XG, UK. : Blackwell Science Ltd
    Fatigue & fracture of engineering materials & structures 27 (2004), S. 0 
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper presents two-dimensional information on the residual stresses in 8 mm 5383-H321 aluminium plates joined by double pass (DP) friction stir welding (FSW). It considers the inherent variability in residual stress magnitudes along 0.5 m lengths of weld pass, and their modification under a sequence of applied fatigue loads. This represents one of a planned series of experiments aimed at illuminating the effects of fatigue cycling on residual stress fields. In this particular case, the magnitudes of the bending fatigue loads (R= 0.1) were chosen to correlate with the measured proof strengths of the weld metal (approximately 160 MPa) and the parent plate (approximately 260–270 MPa). In four-point bend S–N tests at R= 0.1 on 40 mm wide FS welded specimens of this alloy and plate thickness, these peak stress levels correspond to lives of around 105 cycles and 107 cycles, respectively. Results from the work indicate that significant variability exists among welded plates in peak compressive stress magnitudes (a range of perhaps −50 MPa to −140 MPa), although peak tensile stresses were relatively low and more consistent (from around 0 to 30 MPa). Fatigue loading accentuates the peak-to-valley stress change and causes an overall translation of the stresses to become more positive. Peak tensile stresses increase several-fold during fatigue cycling.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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