Abstract
Laser surface remelting is one of the best procedures for surface modification of ferrite–pearlite nodular irons. Using this procedure on cast irons it is possible to achieve a very high wear resistance, which can be compared with the wear resistance of surface hardened heat treatable steels. The properties of the modified layer depend on the microstructure before heat treatment and on the amount of energy input transferred into the surface layer of the specimen. The research work has focused on the study of residual stresses after laser surface remelting of different kinds of grey and nodular irons. The identification of residual stresses was performed using the relaxation method, which involved measuring specimen strain. The results of the measured residual stresses confirm that the stresses strongly depend on laser surface remelting conditions. The measurement of residual stresses is very important in exacting dynamically loaded machine parts, which have been subjected to different kinds of heat treatment. In designing parts designers very frequently demand the presence of compressive residual stresses after heat treatment and finish grinding of the surface, since this increases the fatigue strength of the material and reduces the danger of fracture.
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