Browsing by Author "Knupfer, SM"

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    Characterization of the residual strains in iterative laser forming
    (Elsevier, 2012-01-01) Knupfer, SM; Paradowska, AM; Kirstein, O; Moore, AJ
    In laser forming, thermally induced strains transverse to the laser scan line vary with depth in the material and contribute most significantly to the desired deformation. The through-thickness transverse residual strain distribution was measured by neutron diffraction in laser-formed low carbon steel and aluminium alloy specimens. The specimens were formed with a wide range of laser line energies covering the temperature gradient mechanism (TGM) and shortening or upsetting mechanism (SM), and for single and multi-pass forming (up to 3 laser passes). Below the saturation line energy where the TGM dominates, the gradient of the through-thickness strain distribution was found to increase with increasing line energy and number of laser passes; the gradient decreased again at line energies above the saturation line energy where the efficiency of the TGM decreases. Iterative laser forming can be applied to reduce weld-induced distortions. The peak longitudinal strain measured in the weld seam of a specimen that had been straightened by iterative laser forming was also significantly reduced.(C) 2011 Elsevier B.V.