Title: Microstructure variations in the laser surface remelted layer of nodular iron

Authors: Janez Grum, Roman Sturm

Addresses: Faculty of Mechanical Engineering, University of Ljubljana, Askerceva 6, 1000 Ljubljana, Slovenia. ' Faculty of Mechanical Engineering, University of Ljubljana, Askerceva 6, 1000 Ljubljana, Slovenia

Abstract: The laser remelting process is a very promising hardening method for ferrous and nonferrous alloys because it does not show a homogeneous microstructural state after having been heat-treated in a traditional way. The paper deals with residual stresses in the surface layer of thin flat specimens of nodular cast iron 500–7 in the laser remelting process. Volume changes of the specimen occur due to thermal and microstructural changes in the process of gradual remelting of the specimen surface. For a better knowledge of volume changes in the thin surface remelted layer of the specimen, the latter was evaluated by residual-stress measurement. Such remelting conditions in laser remelting of a workpiece should be ensured so that a uniform thickness of the modified layer can be obtained despite several laser-beam passages across the workpiece surface. The state of internal stress in the workpiece changes because of a multiple laser-beam passage across the workpiece surface. Laser operating parameters were chosen on the basis of knowing the remelted geometry of one laser trace, while the overlapping degree of laser tracks was varied.

Keywords: laser surface remelting; residual stresses; nodular iron; microstructure variations; hardening; cast iron.

DOI: 10.1504/IJMMP.2005.008155

International Journal of Microstructure and Materials Properties, 2005 Vol.1 No.1, pp.11 - 23

Published online: 21 Nov 2005 *

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