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University of Miskolc Department of Mechanical Engineering. Modelling of Laser Surface Treatment. Tutor : Dr. Mária Kocsis Báan Consultant : Mr. Reza Roshan By : Mohamad Honeineh M.Sc. Thesis. Experimental Methodology. Steel grades C45, C60, S100 ( Hungarian standard )
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University of Miskolc Department of Mechanical Engineering Modelling of Laser Surface Treatment Tutor: Dr. Mária Kocsis Báan Consultant: Mr. Reza Roshan By: Mohamad Honeineh M.Sc. Thesis
Experimental Methodology • Steel grades C45, C60, S100 (Hungarian standard) • Workpice dimensions 6056 10 (mm) • Laser beam diametere 10 (mm) • 9 combinations of technological paramerter: • Laser power 1,2,3 (kW ) • Sacnning rates 300,500,700 (mm/min) • Surface coated by graphite
Preparation Stages • Sectioning was accomplished by water jet cutting machine • Grinding • Rough and Fine Polishing • The sectioned specimens were etched in Nital • macro- & microphotos were placed in synchronization with the HV microhardness results
LaserTreated C45 Steel P = 2 kW, v = 300 mm/minP = 2 kW, v = 500 mm/minP = 2 kW, v = 700 mm/min
Experimental Results • No significant changes were observed for 1 kW laser power • For 2 and 3 kW laser power, the phase transformation depth decreased when the scanning speed was the fastest • Slow scanning speeds caused wider and deeper hardened tracks • For high laser power with fast scanning rates high hardness was achieved • Homogeneous austenite was obtained at slow scanning rate
Three Dimensional Modelling • The same geometry was built using SYSWELD SOFTWARE as that in the original experiments • A Conical heat source was implemented into the SYSWELD by using simplified FORTRAN programming • Due to the symmetry of the workpiece, the fine mesh created resembled only half the workpiece
3kW Laser Power v=300 mm/min v=500 mm/min v=700 mm/min
Conical and Gaussian Model qmax v=500 mm/min v=500 mm/min
Conical and Gaussian Model Time-temp. Cycles for C60 steel, at 2 kW and scanning speed 500 mm/min for: Conical heat source model Gaussian heat source model
Simulation Results • Higher was the laser power, higher the temperature • Spot size was greatly influenced by the laser power and scanning rate • Time-Temperature Curves indicate that very fast cooling occurs • Bigger thermal conductivity factor, lower was the Temperature • Gaussian model obtained steeper and sharper cycles than that of a conical model • Changing the absorptivity factor by 0.1 step increment results in 200-300°C difference in maximum temperature