Enhanced Laser Cladding John M. Haake Titanova, Inc St. Charles, - - PowerPoint PPT Presentation

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Weld Puddle Forming and Shaping for Enhanced Laser Cladding

John M. Haake Titanova, Inc

• St. Charles, Missouri, USA

www.titanovalaser.com

LAM 2012

This material is based upon work supported by DOE under award number DE-FG02-08ER84958

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Cladding or Weld Overlay

Cladding or weld overlay makes use of a heat source to melt and fuse [weld] onto the substrate of a component a material that has different and beneficial metallurgical properties. This allows one to cost effectively customize the surface properties

• Corrosion resistance
• Erosion resistance
• Wear resistance = Laser Hardfacing

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Methods for Laser Cladding

• Powder cladding

– Preplaced and Collinear

• Thermal Spray and laser fuse
• Wire feed cladding

– Vertical wire feed cladding

• Hybrid processes

– Hot wire feed

• LISI - Laser Induced Surface

Improvement

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q q q q Wetting angle More desirable

Gaussian shape beam – round spot Rectangular shape beam Line shape beam

23 24 25 3 3 3

Clad Profile Comparison

Dilution held constant

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Typical Cross-sections of clad layers produced by means

• f powder feed cladding with varying energy density= power X velocity

feed rate constant at 5mm/sec . More dilution with the substrate as the power Increases with same surface speed

Flatter Clads = More Dilution

And Less Defects!

1:1 aspect ratio laser beams

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Gaussian Profile Rectangular Profile

Clad Morphology

Line Profile Dilution held constant

• Less risk of entrapped pores

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Benefits of Diode Laser Cladding

• Welded 100% dense = No porosity
• Very Low dilution = High Corrosion resistance
• Small heat affected zone = less distortion
• High quench rates = finer grain structure = higher
• corrosion potentials
• Line Source allows for much wider thinner clads
• Much smoother clads = less post machining
• High Efficiency
• Production worthy enabling one piece flow
• Highly controllable
• Smaller wavelength = higher photon energy = More absorption

– Enables wire feed cladding – Enables strip cladding – Enables spray and fuse cladding

• Small Size

– Enables in-field cladding

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8 Process axis for autogenous welding, wire feed welding and brazing Process Axis for heat treating, cladding, paint stripping, surface melting, composite manufacturing

Focus Configuration for Top-Hat Line Source

The line source is necessary to achieve thin flat low dilution clads.

12 X < 0.4 mm line @ focus - 125 mm

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This is the beam profile from a ISL-2000LHD where the FWHM is approximately 6 mm X <400 microns. There is no additional improvement in the fast axis [short axis of the focused spot] by double macro lensing. Note the broader wings

Fast Lensed Direct Diode Laser

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Laser Cladding - What is Desirable Job Shop Perspective

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• Thin flat low dilution clads
• Increased deposition efficiency without loss of good morphology
• Material insensitivity
• Base material insensitivity
• Gas coverage insensitivity
• Base material shape insensitivity
• Base material position insensitivity
• Edge definition
• Zero defects
• System robustness

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Increased Deposition Efficiency

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It is desirable to have high deposition efficiency without loss of surface morphology AND

Low Dilution

4000 Watts line source 80/20 NiCr 0.1% Fe

6.0 lbs. 6.0 lbs. 8.8 lbs. 12.3 lbs. 7.0 lbs. 9.2 lbs.

4.7% Fe 3.0% Fe 0.7% Fe cm2/Watt NOT kg/hr.

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Tie in

This material is the tie-in material

First Pass Second pass Machine surface For clean up Required overlap Step over distance Third pass

Overlap Necessary for Good “Tie-in”

It is typically necessary to apply more heat to achieve good morphologies More Dilution

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Process Material Insensitivity

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Is desirable to have a clad process that is insensitive to base material chemistry, clad materials chemistry, gas coverage, and environment

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Mechanical Insensitivity

14 Base Material shape - It is desirable to achieve the same morphology over 3D surfaces

Clad Material Shape – It is desirable to achieve the same morphology independent of the clad material shape Hot Wire Laser Cladding

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Weld Position Insensitivity

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5G Welding It is desirable to achieve the same clad morphology and dilution independent of weld position.

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Edge Definition

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Inside edge requirement is for no pores for 100% cleanup

• Requires different laser parameters
• Different beam shape
• Higher dilution
• Separate process step

Pore – incomplete fusion Need clad to extend over edge for good clean-up

• Requires different laser parameters
• Different beam shape
• Higher dilution – Edge melting
• Separate process step

Inside Edge Outside Edge

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Zero Defects

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Rework =

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System Robustness

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• Highest deposition rate = High power

High Power = Big Problem!

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KISS Principal

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No way in a job shop environment!

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Separation of Variables

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Robust High power Laser cladding systems

• Maximized High power lasers
• Maximized deposition rates
• Extensive peripheral cooling
• Expensive

Cladding nozzles optimized for high powers

• Peripheral Cooling
• Gas coverage

Primary Laser Secondary lower power laser Optimized for flexibility Optimized for beam manipulation Independent from Primary laser Not collinear with Primary laser Inexpensive

WELD puddle creator

WELD puddle manipulator

Patent Pending

$

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Surface Tension = Primary Force

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• The Primary laser is the “work horse” it melts the clad material and

creates the weld puddle

• The Secondary low power laser is used to influence the weld puddle
• Maintaining a molten state is a strategic location longer
• Affecting surface tension properties in a beneficial way

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Step over distance ds Overlap distance do

Optimized Shape for “Tie-in”

Clad progression Patent Pending

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Robust High Power Laser Lower power laser Molten Weld Overlay puddle

Laser Weld Overlay Puddle Shaping

Patent Pending

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Examples of 4000W Line Cladding Source with Varying Secondary Laser Power

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0 Watts 110 Watts 210 Watts 632 Watts 1050 Watts

Not optimized

Patent Pending Secondary Laser

• n Right

36:1 19:1 6:1 4:1

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4000W diode laser Line beam

LaserLine fiber coupled 300mm FL

Edge Work piece

Outside Edge Definition

Patent Pending

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4000W Line Source Cladding with Secondary Laser on Edge

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0 watts 400 watts 800 watts Patent Pending

Not optimized

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Potential Benefits of In-situ Puddle Forming and Shaping

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• Increase deposition rates = cm2/W
• Improved morphology [flatter thinner clads]
• Lowering dilution [ Less heat for tie in]
• Clad material independence
• Based material independence
• Cover gas independence
• Base work piece shape independence
• In situ defect mitigation [fixing blow holes]
• Outside Edge definition
• Edge definition around holes
• Inside fillet definition
• In Situ defect mitigation
• Thinner clads with less defects
• Control of solidification cracking issues
• Improving wire feed laser cladding
• 3D build up

Patent Pending

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Thank You Titanova, Inc.

This material is based upon work supported by DOE under award number DE-FG02-08ER84958

ASME S,U and R Stamp Certified ISO:9001:2008 Certified