Research On Micro-cracking Mechanism Of Laser Repairing Area And Influencing Factors

Laser repairing technology is widely used in the field of repairing mechanical equipments.After repaired by laser, surface of mechanical equipments can get excellent repairing layer,but the laser repairing layer easily cracks to produce micro cracks. Under the action of theresidual tensile stress or external tensile force, micro cracks suffer extension and continue tocrack into macroscopic cracks. The cracks will crack through the laser repairing layer. Whenit is very serious, it perhaps leads to the repairing layer dropping from the substrate. It causessevere damage to whole property of the repairing layer. So research on the crackingmechanism of laser repairing layer and influencing factors has an important practicalsignificance.In order to get excellent property laser repairing layer without cracks，it needs to researchthe cracking mechanism of laser repairing layer, the main influencing factors of layer cracksand the influencing rule of influencing factors to repairing layer. Through the numericalsimulation to analyze the related law of laser repairing thermal response and repairing layercracks, it can clear the influence law of the temperature gradient and temperature changingrate on repairing layer cracks, the distribution characteristics of the residual stress in therepairing layer, and the influence law on the repairing layer cracks. Then combining with therepairing experimental analysis, it can get the cracking mechanism of laser repairing layer andthe main influencing factors influencing the repairing layer cracks. Through numericalsimulation analysis of finite element model of graphite piece and laser repairing experimentalanalysis, it researches the stress distribution of graphite piece tip and phase morphologicalcharacteristics. Then it gets out the influencing law of graphite piece on laser repairing layercracks, and discusses the influencing factors on stress distribution and morphology of graphitepiece. Through the laser repairing numerical simulation and laser repairing experiments, it researches the influencing law of specific energy, slow cooling measure and repairing powderthickness on laser repairing layer cracks. Then it chooses the best combinations of processparameters, slow cooling temperature and the thickness of repairing powder according to theinfluencing laws. The above method can be used to study the cracking mechanism andinfluencing factors of laser repairing layer crack, it can choose suitable laser repair technologyaccording to the cracking mechanism and influencing factors.According to the cracking mechanism of laser repairing layer crack and the maininfluencing factors on the repairing layer cracks, it selects the best process parameters, slowcooling temperature and the thickness of powder, and put forward a set of controlling crackscheme. It can strengthen the integration level of the substrate and the repairing layer, reducethe repairing layer cracking rate, reduce the number repairing cracks and improve the qualityof repair layer.