Deliverables Increase of the operating safety of critical metalworks and prevent of their catastrophic failure The following main achievements have been reached as a result of the execution of the Project: 1. The parameters for laser and electron beam treatment allowing a homogeneous structure of modified zones to be reached and to provide cracks retardation have been defined. Special fast pyrometer was developed for real-time surface temperature measurements. Experimental thermocycles allow for the optimisation of treatment conditions in order to reach homogeneous structure and required depth of the melt pool. 2. 2D transient heat transfer model has been developed. This model includes the processes of heating, melting, surface evaporation, solidification, cooling and phase transformation induced by the action of unsteady concentrated heat flux. The results of application of the developed model are in good correlation with the experiments. Therefore, this model could be successfully applied for correct choice of treatment parameters in order to ensure the required depth of the modified zone. 3. The microstructures of treated materials have been studied. The rapid melting and solidification process modify the chemical composition of the surface layer of aluminium alloy 3003 (97.0% aluminium, 1.2% manganese, and lesser amounts of silicon, iron, copper and zinc). As shown by the Auger spectroscopy, after melting, the dispersed second phases ((Mn, Fe)Q16, i.e., MnA16 containing some dissolved iron substituted for manganese, and a-A1(Mn, Fe)Si) are dissolved and the modified zone has a homogeneous structure at optimum treatment conditions. The microstructure of carbon steel after surface treatment has a many layers structure: homogeneous martensite; martensite including lamellar perlite; mixture of martensite, austenitised pearlite and ferrite grains. 4. The mathematical modelling of laser plasma in the frame of 2D radiative gas dynamics has been carried out to take into account the laser beam attenuation. The results of calculation have shown that the attenuation level could reach 0.03 and it should be taken into account for process optimisation. 5. The method for treated sample failure resistance tests under cyclic loads has been developed. The examination of fatigue properties of treated and initial samples was carried out by bending test. The frequency of sinusoidal cyclic loading was 50 Hz. The bending stress Ga was calculated using the experimental data for bending movement and it was presented as an S-N curve (against a number of cycles to fracture). Cracks behaviour was analysed with the help of optical microscopy and SEM during cycling testing. Processes of cracks growth, coalescence, deflection and retardation have been studied in order to define optimum treatment conditions allowing increase of the total lifetime. The fatigue limit has been increased as a result of laser and electron beam treatment under optimum conditions. The analysis of the failure resistance tests shows the propagation of fatigue cracks could be retarded within the modified areas having a cellular structure. This mechanism is responsible for longer (in about 1.5 times) fatigue life. Searching for OpenAIRE data... There was an error trying to search data from OpenAIRE No results available
