Laser%20Surface%20Treatment%20of%20Materials%20and%20it

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Laser Surface Treatment of Materials and its
Modelling using FEM

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• Reza Rowshan
• Department of Mechanical Engineering

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Experimental Procedure
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Material used for the experiments
Coating graphite
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Experimental Results
 P 1000 W
 P 2000 W
 P 3000 W
 V 300 mm/min
 V 500 mm/min
 V 700 mm/min
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Treated Zones Analysis
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Microhardness Testing
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Microhardness Testing
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Microhardness Testing
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FEM Analysis
SYSTUS Environment
SYSWELD software is directly derived from the
SYSTUS system can determine the residual stresses
and strains resulting from welding or heat
treatments (quenching, induction quenching,
surface treatment) as well as diffusion
precipitation and hydrogen diffusion .
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SYSWELD general architecture
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Steps of Modelling

• Description of the problem
• Modelling of the part
• Heat transfer and metallurgical computation
• Metallurgical data
• Computation stage

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Steps of FEM alnalysis

• Geometry
• Heat transfer
• Metallurgical transformations

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Geometry

• Two dimensional modelling
• Three dimensional modelling

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Heat transfer

• Thermal properties
• Thermal conductivity
• Specific heat and density
• Velocity of the heat source
• Thermal boundary conditions
• Imposed temperature
• Heat transfer coefficient
• Heat source distribution.

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Heat Source Distribution Modelling
2D heat source
Conical heat source
Gaussian heat source
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Metallurgical transformations

• To introduce the
• metallurgical data of the
• material to the software one
• should create a file called
• METALLURGY.DAT.
• The metallurgical
• parameters are extracted
• from the CCT diagram of
• the material using the
• cooling curves.

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2D and 3D Results
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Scanning rate comparison
Time-Temp. Cycles at scanning rates
---- v300 ---- v500 ---- v700
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Power comparison
Time-Temp. Distribution at Power ---- P 3
kW ---- P 2 kW ---- P 1 kW
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Heat source comparison
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Heat source comparison
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Absorptivity comparisons
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Result of Modelling
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Temperature DistributionPower of 1kw
   
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Temperature DistributionPower of 2kw
 
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Temperature DistributionPower of 3kw
   
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Conclusion

• From the micrograph of the 9 combinations of
  parameters it has been concluded that by
  increasing the laser power the heat effected zone
  increases. Meanwhile increase in the laser
  scanning rate cause decreasing in the width and
  depth of effected zone.
• To reach maximum hardness, the laser power should
  be high enough to melt the steel under
  examination and at the same time the heating and
  cooling rate should be very fast. In our case
  highest hardness values were reached by laser
  power of 2 kW and scan rate of 700 mm/min. The
  reason why the hardness is less in 3 kW laser
  power is that the cooling rate is longer than
  that of 2 kW.
• Results of computer simulation are compatible
  with experimental ones. Increasing the laser
  power surface temperature and depth of the melt
  pool will increase. Similarly to the experimental
  results, depth of the melt pool decreases by
  increasing the scan rate.