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 2
Strategic Positioning for Shipbuilding 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 3
Automated Manufacturing Techniques for Shipyards 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 4
Robotic Welding 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 5
Automated Manufacturing with Hybrid Laser Arc Welding Laser GMAW (MAG) Keyhole Electrode Welding direction Work piece Melted zone Fusion zone Backing gas feeder
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-t 8/5 : 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 Fit-up unpredictable-costly repair/rework Process Submerged Arc* HLAW LW with filler Speed 100% 300% 150% Thickness <12mm <15mm <15mm Gap 2-5 mm 0-1 mm 0-0.4 mm Distortion <1.5 mm/m <0.2 mm/m <0.1 mm/m Metallurgy Not critical Not critical Critical Fatigue Good Excellent Critical Submerged Arc High heat input High distortion Vey high amount of rework to bring back distortion *source/www.fronius.com
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 Fillet Joint Assembly HLAW-10 mm thick steel, single pass butt weld HLAW-3 mm thick Al alloy Butt Weld HLAW-Al alloy (fillet joint)
Results on HSLA 65 in partnership with DRDC Atlantic 600 HV 500gf 400 200 BM HAZ FZ HAZ BM 0-9 -6-3 0 3 6 9 Distance from weld center [mm] 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 Requirement per ASTM A945 450 MPa (minimum) 540-690 MPa 22 % (minimum) Ready for technology demonstration on other alloys/grades, thicknesses, different laser types) 10
Inline Non destructive inspection of welds by laser-ultrasonics Generation laser Welding Laser Detection laser & interferometer GMAW (MAG) Keyhole Electrode Welding direction Inspected part Work piece Defect Melted zone Fusion zone Backing gas feeder
Laser-ultrasonics: principle Ultrasound Generation laser Flaw Detection laser Interferometer Data acquisition Computer 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 12
Assessment of welds in parts Detail of a fillet weld Complex geometry (Suspension mainframe) 13
Inspection and characterization approaches Lasers scanning lack of fusion penetration Shape of weld nugget obtained by laser surface profilometry Lack of fusion (end of fusion zone) obtained from laserultrasonics 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 interface top surface penetration 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) Generation laser a Detection laser & interferometer Defect Inspected part 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 d i c 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. z 16
Application to Friction Stir Welding Laser ultrasonics: frequencies up to 220 MHz allow the detection of small defects such as oxide remnants B-scan across the weld hooking kissing bond (oxide remnants) wormhole C-scan near bottom Lack of penetration B-scan Backwall 17
Hybrid Laser Arc welded HSLA 1.7 mm length Weld length = 40cm Plate thickness= 9 mm Porosity observed by x-ray digital radiography all along the weld bead + 2 linear defects X-ray digital radiography picture (size 5x5cm) showing one of the identified linear defects (marked by the red arrow) 18
HLAW HSLA: LU + SAFT results 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 2 to 3 mm 5 to 6 mm 8 to 9 mm 3 to 4 mm Linear defect seen by X-ray radiography 6 to 7 mm 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 4 to 5 mm 7 to 8 mm 19
HLAW HSLA: linear defect 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) 20
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)
NRC s National Scope 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 Over 4,000 employees Surface Transportation and 1,500 visiting workers Research facilities Industry support 2010-2011 budget: $749M
Our role in the R&TD continuum* Research and Technology (R&T) Development (D) Breakthrough Research Development of Critical Technologies Technology Validation Demonstrators Prototypes Universities Product Definition Product Design and Development NRC Product Qualification Industrial R&T Production -10-5 years 0 +5 Fundamental Research Applied Research TRL 0 3 6 9 Advanced Technology Demonstration Product / Process- Specific Technology Development * 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 Need for Research Definition of Work Participation in Work Cost of Research Downstream Benefits Ownership in tangible media * Use of data * Exploitation of Arising IP Fee-for-Service Testing/Inspection Research One sided Shared Collaborative R&D Terms negotiated on a case-by-case basis 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