laser materials processing: atom to applicationlaser materials processing: atom to application j....

1Center for Laser Aided Intelligent ManufacturingUniversity of Michigan, Ann Arbor

Laser Materials Processing: Atom to ApplicationJ. Mazumder

Robert H. Lurie Professor of Engineering

FEL users’ workshop at Jefferson Laboratory

January 18, 2002


OutlineOutline•Introduction

•Modeling & Measurement

•Applications

•Precision Machining

•Aluminum Welding

•Remote Welding of Galvanized Steel

•Surface Alloying of Aluminum Engine

Direct Metal Deposition

Designed Materials

Nano-Structured materials

•Summary and Conclusion


Mission

• Apply atomic level understandingto Laser aided manufacturingapplications to reduce the lead-time for concept to product


Center For laser Aided Intelligent Manufacturing

Goal

Approach

Modeling

Measurement

Applications Direct Materials Deposition

Designed Material

Drilling

Industrial Sponsors:

PLM Consortium: 19 MajorIndustriesAetna, General Motors, FORD

A

AB

a

b

ca

d

Welding

Scanning Electron Microscopy and X-Energy Dispersive Spectroscopy

CAD Model of Negative CTE Specimen (White- nickel,Yellow- Chromium)

Negative CTE Specimen

• To develop a fundamental understanding of laser-aided intelligent manufacturing to reduce lead-timefor concept to product.

• To transfer this technology to industry

• To educate both students and industrial personnelin the basic cross-disciplinary science andtechnology

• To develop a fundamental understandingof laser-aided intelligent manufacturing toreduce lead-time for concept to product.

• To transfer this technology to industry

• To educate both students and industrialpersonnel in the basic cross-disciplinaryscience and technology

Aluminum welding: TRW Diode-pumped Nd:YAG vs. conventional flashlamp-

pumped Nd:YAG

Remote Laser Welding of Galvanized and Galvanneal Steel

Successful test welds obtained with Copper foils, process to bePatented

Schematic

Typical Weld result

Parameters

Stress-Strain Diagram

•Power: 3.0 kW•Speed: 75 ipm•Helium: 37 SCFH•Argon: 15 SCFH•Laser: Trumpf CO2 Laser•Material: Hot-dipped

Galvanized Steel

Porosity: 1%

Consistent Strength of 71 MPa

-2.00 -1.00 0.00 1.00 2.00

3.00

2.00

1.00

Radial distance from plume center (mm)

Hei

ght a

bove

wor

kpie

ce (m

m)

0.00 10.00 20.00 30.00 40.00Density (arb units)

IMS-T1 H13 Sample Corepart

Cavity part

H13 tool steel with copper chill block and conformal coating

Electron Density Distribution by Absorption Spectroscopy

HDM

SB

DMD

FiniteElementModel

SolidModel

Homogenization Design Method Direct Material Deposition

AluminumWelding

Steel Welding

Reflective Topography

Measurement of the Liquid Free-surface deformation

Temperature and Velocity profile for High Power Density Welding

SEM and XEDS of H13-Cu interface produced by DMD

GovernmentSponsorsDARPA, GNR, NSF

Contact:Marti [email protected]

a b

c d

0

50

100

150

200

250

300

350

0 2 4 6 8 10 12 14 16

base stressAW stressT6 stressSc stress

0

50

100

150

200

250

300

350

0

50

100

150

200

250

300

350

0 2 4 6 8 10 12 14 160 2 4 6 8 10 12 14 16

base stressAW stressT6 stressSc stress

base stressAW stressT6 stressSc stressba

se s

tress

base strain

Stress-Strain Curve for Sc welded Al 6061-T6

Cycle Time reduction by 10-50%

Aluminum Welding of 6061-T6 using Sc filler wire results in increased elongation

DPSS Laser Drilled Hole in Al-SiC Composite. Negligible recast layer.


Mathematical Model Features• 3 dimensional fluid flow/heat transfer

– Thermo-capillary force, recoil pressure, capillary effect– Symmetrically Coupled Gauss Seidel Method (SCGS)

• Vanka [1986] J. Comput. Physics• L/V interface BCs: level set formulation

– Sussman, Smereka, Osher [1994] J. Comput. Physics.• S/L interface BCs: mixture continuum model

– Bennon, Incropera[1988]• Multiple reflections• Homogeneous boiling/ Evaporation• Free surface evolution: Level set method


Evaporation: Knudsen layer jump conditions• Knight’s model[1979,AIAA journal]

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Simulation with recoil pressure


Spectroscopy Equipment


Density vs. Height


Predictions• Microstructure look-up maps for laser welding

conditions are not available.• A look-up map has been extrapolated from

available data in the literature• Dendrite tip radius was found to vary in the range

of 0.6x10-6 to 2x10-6 � (P=3450W, V=4.45 cm/s)


Alloying based laser welding of galvanized steel ICALEO 2000

Process details

At 1083 deg. C ( MP of Copper )


Alloying based laser welding of galvanized steel ICALEO 2000

Mechanical test results

Geometry of tensile samples

Stress-Strain plot for P=3.0 kW, S=75 ipm

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

0 5 10 15 20

% Strain

Stress-Strain plot for P=3.5 kW, S=80 ipm

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

0 5 10 15

% Strain

83 MPa 83 MPa


Solid State Laser Options

Lamps Nd: YAGRods

Diode LaserArrays

Nd: YAGSlabs (Rods)

Diode LaserArrays

CouplingOptics

3-4

7-10

25-35

WallplugEfficiency (%)

Delivered PowerAve W/cm2 Peak W/cm2

Applications

Welding, cutting,drilling, cladding

Precision drilling,cutting, deep welding,paint stripping

Soldering, hardening,brazing, plasticwelding, surfacetreatment

3 x 106

2 x 108

5 x 104

6 x 106

3 x 109

2 x 105

LPSSL

DPSSL

Direct Diode Laser


Advantages of High-BrightnessLasers For Reflective Materials

• Small focused beams for precisionapplications

• High intensities for faster speeds or deeperpenetration

• Long depths of focus• Use of very long focal length lenses


Penetration vs. traverse speed for 150 mm lens,

Power 400W

0

0.5

1

1.5

2

2.5

3

3.5

0 20 40 60 80 100 120

Traverse Speed (ipm)

Pene

tratio

n (m

m)

666 Hz500 Hz400 Hz


TEM Image

TEM image of Al 5754 weld zone


Distortion-Free Welding of Steel Plate

Excellent weld uniformity is shownin this longitudinal cross-section

Virtually no distortion in thick-section welded plate

Material: 70 mm thick mild steel(welded from 2 sides)

• Extremely thick cross-sections may bewelded with no measurable distortiondue to parallel-walled fusion zone

- only small hold-down clamps wereused to restrain parts

• Deep welds show consistent uniformity

• performance is limited by availablematerial

laser materials processing: atom to applicationlaser materials processing: atom to application j....

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