Heat Absorption in Laser Cladding

1
Heat Absorption in Laser Cladding
TPTC Seminar 03/05/2004

• Guofang Zhou
• Prof. Calvin Tszeng
• Prof. Philip G. Nash
• Dr. Zhiyong Hu

2
Objectives

• To gauge the absorption rate by computation and
  experimentation
• To use computational tool to investigate the
  phenomena in melting stage

3
Process Description

• The surface lattices absorb the energy from
  photons and conduct to the workpiece.
• Only part of the laser energy is absorbed.
• The absorption depends on the laser wavelength,
  power, incident angle, surface temperature,
  interaction of laser with the material etc.
• The power into the workpiece determines the
  quality of the product

Laser Beam
Wire Feeding
Workpiece Moving Direction
4
Strategy to Obtain the Absorption
5
Assumption

• The laser focus area is rectangle.
• The size depends on the working distance
• Here we take 12 mm 0.5 mm which is at the focal
  distance.
• Full output power which is 4000 W is used on the
  top surface.
• The output heat has an evenly rectangle profile.
• Heat flux rate is 640,000 kW/m2

6
FEM Model
Top View
Heat Flux

• Simplify to two dimensional plane-strain heat
  transfer problem
• All other surfaces are insulated

7
Thermal Property Data of Cu-Ni
8
Specific Heat of Cu-Ni
9
Calculated Results from HOTPOINT

• Temperature Unit C

Temperature Contour at 0.002 Second
HOTPOINT by Prof. Tszseng was used to perform
the calculation
10
2-D Results from ABAQUS
T (K)

• Temperature contour at 0.002 s

11
2-D Results from ABAQUS

• Temperature histories of the points on the top
  surface

12
3-D Results from ABAQUS
T (K)

• Temperature contour at 0.002 s

13
3-D Results from ABAQUS

• Temperature history at the corner point of the
  shooting area

14
Temperature History
2-D
3-D
15
Conclusion

• If the absorption rate is 100, the melting time
  for the top surface of the sample is about
  0.00150.0025 seconds

16
Future Work

• Determine the temperature dependent thermal
  conductivity either by calculation or experiments
• Comparison between IR experiments and
  computational results to determine the absorption
  rate
• Develop model for laser cladding with wire
  feeding
• Investigate the melting phenomena