Laser Technologies for Welding and Inspection Photonics for Shipbuilding Workshop

Dr. Priti Wanjara, Dr. X.Cao, NRC (Automated Manufacturing)

Dr. J-P Monchalin, Dr. D. Levesque, Dr. G. Rousseau, NRC (Inline Non Destructive Inspection)

Dr. A. Nolting and C. Munro, DRDC Atlantic,

(Performance Evaluation)

November 20, 2012

Overview

• Strategic positioning for shipbuilding • Hybrid Laser Arc Welding • Non-destructive Inspection • NRC a partner of choice

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Strategic Positioning for Shipbuilding

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Judicious investment to improve production capabilities through new technologies to Increase competitiveness (cost, delivery and quality) in a global market Increase productivity Increase flexibility Increase cost-effectiveness

Improve/automate (emerging) engineering processes Reduce material inputs or reuse materials Mitigate/eliminate hazardous waste and pollutants to the

environmental safety and health in a shipyard

Conventional shipbuilding is labor intensive Automation can increase efficiency Automated and optimized manufacturing processes Planning entire sequence of operation (factory of the future) for seamless flow of resources (labor, equipment, materials, space, time) Robotized production cells (welding, cutting) Production logistics (inspection) and data collection

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Automated Manufacturing Techniques for Shipyards

Robotic Welding

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Manual arc → Robotic arc → Hybrid laser arc welding Increase production rate Reduce filler metal usage Reduce preparatory clean up prior to welding Improve fit-up Decrease shielding gases usage Reduce reworking and material scrap Increase operator efficiency Increase safety

Automated Manufacturing with Hybrid Laser Arc Welding

Welding direction

Laser

GMAW (MAG)

Fusion zone

Keyhole

Melted zone Backing gas feeder

Electrode

Work piece

Manufacturing Process Differences

Motivation (Synergistic effect of laser and arc) •Laser Welding alone •Low heat input (thermal load) and fewer passes for thick welds •High energy density, weld speed, penetration depth •Low distortion (high weld strength reduced low temperature properties) •Low gap tolerance (issue for long products)

•Arc Welding alone •High gap tolerance (gap bridging ability) •Process efficiency, low capital costs •Slow cooling rate (influence structure-t8/5: time between 800-500°C)

•Hybrid Laser Arc Welding •Plasma of laser reacts with plasma of arc and stabilizes arc at high speeds •High economics (filler wire/shielding gas) •Seam quality improved

Process Comparisons

*source/www.fronius.com

Submerged Arc* 100%

<12mm 2-5 mm

<1.5 mm/m Not critical

Good

HLAW 300%

<15mm 0-1 mm

<0.2 mm/m Not critical Excellent

LW with filler 150%

<15mm 0-0.4 mm

<0.1 mm/m Critical Critical

Process Speed

Thickness Gap

Distortion Metallurgy

Fatigue

Submerged Arc High heat input High distortion Vey high amount of rework to bring back distortion

Fit-up unpredictable-Costly repair/rework

Robotic Hybrid Laser Arc Welding (HLAW)

Industrialized solution for “tandem” welding with local shielding gas protection by integrating a IPG-5.2 kW continuous wave fiber laser welding system with a Fronius Cold Metal Transfer MIG welding system • Hybrid technology gives high penetration depth, gap

filling capability, chemistry adjustment of weld pool with minimized distortion

• Butt and fillet joints • Demonstrated expertise in joining of high strength

steels (HSLA-65, HSLA-80), Al alloys (6xxx) • Design and fabrication of devices for localized

shielding/gas protection of weld pool

HLAW-Al alloy (fillet joint)

HLAW-10 mm thick steel, single pass

butt weld

HLAW-3 mm thick Al alloy Butt Weld

Fillet Joint Assembly

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Results on HSLA 65 in partnership with DRDC Atlantic

Requirement per ASTM A945

450 MPa (minimum)

540 - 690 MPa 22 %

(minimum)

HLAW with single pass, one side Butt joint assembly of 10 mm thick HSLA-65 steel Low shielding gas cost (~3L/min vs arc 15L/min) Low distortion (<1°), good properties 3 journal publications-phase 1 phase 2 evaluation ongoing Ready for technology demonstration on other alloys/grades, thicknesses, different laser types)

0

200

400

600

-9 -6 -3 0 3 6 9

Distance from weld center [mm]

HV

500g

f

HAZ FZ HAZBM BM

Inline Non destructive inspection of welds by laser-ultrasonics

Welding direction

Welding Laser

GMAW (MAG)

Fusion zone

Keyhole

Melted zone Backing gas feeder

Electrode

Work piece Inspected part

Generation laser

Detection laser & interferometer

Defect

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• Generation and detection spots can be superimposed and can be of any size and shape: point, small disk, line, etc.

• Can be optically scanned, inspected part being stationary • Non-contact: hot products, can inspect immediate after welding, close to

the plasma source • Can inspect contours of complex geometry • Broad frequency bandwidth: good spatial resolution, small flaws

Laser-ultrasonics: principle

Generation laser

Detection laser

Interferometer

Data acquisition Computer

Ultrasound

Flaw

Assessment of welds in parts

Complex geometry (Suspension mainframe)

Detail of a fillet weld

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Inspection and characterization approaches

penetration

lack of fusion

Lasers scanning

• Shape of weld nugget obtained by laser surface profilometry

• Lack of fusion (end of fusion zone) obtained from laser-ultrasonics

• Penetration of nugget derived from laser ultrasonic data and proprietary algorithm based on the difference of microstructure between the weld nugget and the parent metal

Results of weld inspection and characterization

plate interfacetop surfacepenetration

Metallographic image obtained after sectioning the weld with superimposed in red and yellow results derived from profilometry and laser-ultrasonics

Laser-ultrasonic image provided by the sensor Nugget penetration is then calculated (yellow indication in the image above)

Laser-ultrasonics combined with the Synthetic Aperture Focusing Technique (SAFT)

Sketch of the data taking system: a 1D or 2D array of ultrasonics signals (A-scans) is recorded by focusing the beams onto the surface

Processing by the Synthetic Aperture Focusing Technique of the array of signals to get 3D mapping of the flaws: all signals are delayed according to the propagation time between their origin on the surface and any point in the volume and then summed up to reveals indications/defects.

Inspected part

Generation laser

Detection laser & interferometer

Defect

a

di z

c

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B-scan across the weld

Laser ultrasonics: frequencies up to 220 MHz allow the detection of small defects such as oxide remnants

Application to Friction Stir Welding

wormhole

hooking

kissing bond (oxide remnants)

B-scan

Backwall

Lack of penetration

C-scan near bottom

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Weld length = 40cm Plate thickness= 9 mm Porosity observed by x-ray digital radiography all along the weld bead + 2 linear defects

Hybrid Laser Arc welded HSLA

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X-ray digital radiography picture (size 5x5cm) showing one of the identified linear defects (marked by the red arrow)

1.7 mm length

SAFT processing provides information over the whole volume underneath the scan area Below: slices at various depths over an area 15x15mm around the identified linear defect

HLAW HSLA: LU + SAFT results

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2 to 3 mm

3 to 4 mm

4 to 5 mm

5 to 6 mm

7 to 8 mm

6 to 7 mm

8 to 9 mm

Linear defect seen by X-ray radiography

• LU scanning from the back surface

• Depths are from the back surface

• Shown C-scans are the average of 10 individual C-scans 100 µm apart over 1mm thick slice

HLAW HSLA: linear defect

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Averaged C-scan 4 to 5 mm B-scan parallel to weld axis

This linear defect which appears discontinuous is located at approximately mid-depth (4.5 mm from the back wall)

NRC a Partner of Choice for Industry Full support for technology demonstration and transfer to industry

through leveraging of multi-disciplinary competencies and resources (e.g. different high power laser welding systems) across different government laboratories/departments (manufacturing technology selection, process

development and optimization, performance evaluation, quality assurance, procurement requirements/costs, automated cell layout, laser safety,

personnel training)

Research facilities Industry support

NRC’s National Scope

Over 4,000 employees and 1,500 visiting workers

2010-2011 budget: $749M

Aerospace Aquatic and Crop Resource Development Automotive Construction Energy, Mining and Environment Human Health Therapeutics Information and communications technologies Measurement Sciences and Standards Medical Devices National Science Infrastructure Ocean, Coastal and River Engineering Security and Disruptive Technologies Surface Transportation

Our role in the R&TD continuum*

Development (D) Research and Technology (R&T)

Breakthrough Research

Development of Critical Technologies

Product Definition

Product Design and Development

Production

Product Qualification

years 0 +5 -5 -10

Demonstrators Prototypes

Universities

NRC

Industrial R&T

Fundamental Research

Applied Research

Advanced Technology Demonstration

Product / Process-Specific Technology Development

Technology Validation

TRL 0 3 6 9

* after EADS

Mission

Help industry assess, demonstrate, adapt and implement technologies that have the potential to:

• decrease the life cycle cost of products • make them globally competitive

Develop, adapt and improve innovative technologies to provide a competitive edge to Canadian industry (i.e. fill selected technology gaps) Target significant efforts at Canadian SMEs to strengthen their capabilities and competitiveness Contribute to the education and training of highly qualified engineering personnel for the benefit of Canadian industry

Partnering with NRC

Fee-for-Service • Testing/Inspection

• Research

Collaborative R&D Terms negotiated on a case-by-case basis

N e e d f o r R e s e a r c h

D e f i n i t i o n o f W o r k

P a r t i c i p a t i o n i n W o r k

C o s t o f R e s e a r c h

D o w n s t r e a m B e n e f i t s Ownership in tangible media * Use of data * Exploitation of Arising IP

One sided Shared

For SMEs

Questions: Contacts

Dr. Priti Wanjara, Group Leader Metallic Products Joining and Forming,

(514) 283-9380 or write to priti.wanjara@cnrc-nrc.gc.ca

or Dr. Jean-Pierre Monchalin, Process Diagnostics,

(450) 641-5116 or jean-pierre.monchalin@cnrc-nrc.gc.ca