March 28, 2013 Economics of Advanced Welding Techniques Stephen Levesque Director, EWI Nuclear Fabrication Center Office: Mobile:

Nuclear Fabrication Consortium  Some information in this presentation was based upon research funded by the US Department of Energy through the Nuclear Fabrication Consortium (operated by EWI)  The Nuclear Fabrication Consortium (NFC) was established to independently develop fabrication approaches and data that support the re- establishment of a vibrant US nuclear industry

Overview  Laser Welding ─Process description (Laser and Hybrid Laser Technologies) ─Potential applications ─Cost benefit  Friction Stir Welding ─Process description ─Potential applications ─Cost benefit  Cladding Technologies ─Comparison of various technologies  Tandem GMAW (bonus)

Laser Welding

Laser Background  Solid-state laser technology is rapidly advancing ─Output powers are continuously increasing ─Price per kilowatt is dropping (~$750K for 20-kW) ─Improved portability and electrical efficiency ─Improved beam quality – fiber deliverable  Two laser technologies primarily responsible ─Fiber Laser (IPG Photonics) ─Disk Laser (Trumpf)  ROI for laser processing is becoming more attractive ─Cost/watt, cycle time, penetration, distortion

Advantages and Challenges  The main advantages of laser processing include: ─High productivity ─Low heat input ─Minimal distortion  Some challenges include: ─Critical joint preparation due to limited gap bridging ─Increased capital cost compared to traditional arc-welding equipment in. gap in. gap0.015-in. gap

General Terminology  Autogenous Laser Welding Shielding gas Laser Beam Laser- Induced Vapor Plume Laser Keyhole or Vapor Cavity Liquid Weld Pool Solidified Weld Metal

General Terminology  Hybrid Laser-Arc Welding (Hybrid Welding) ─The combination of two welding processes in the same weld pool ─Most often GMAW and Laser Welding Laser Beam GMAW Torch

“Arc-Leading” HLAW “Laser-Leading” HLAW Hybrid Terminology  The HLAW process can be used in two orientations:

 High-level cost model built by EWI  Assumes 1 min. of arc time for GTAW and 2 sec. of laser time per tube  Varied process efficiency to evaluate the ROI Laser Tube Sheet Welding

Containment Welding  Hybrid Laser-GMAW welding vs. Tandem GMAW vs. Submerged Arc Welding

Productivity  For one weldment X long "10" 50-in Parts "10" 200-in Parts Hours SAW1127 Tandem818 HLAW1516 Includes setup time and weld time

Cost Comparison "10" 60-in Parts "10" 200-in Parts Dollars SAW$48k$124k Tandem$38k$84k HLAW$69k$72k  For one weldment X long Equipment Cost SAW$55k Tandem$150k HLAW$950k Includes setup time/weld time and filler metal cost

Combined Comparison Data 200-in

Other Benefits  Peak Temperature Models showing reduction in heat input SAW GMAW-T HLAW

Distortion and Residual Stress SAWTandemHLAW

Friction Stir Welding

 Invented by TWI in 1991 ─Wayne Thomas  Solid-state joining process ─No bulk melting of the substrate  Capable of joining ─Aluminum, Magnesium, Copper, Steel, Titanium, Nickel, many more  Non-consumable tool rotates and traverses along a joint ─Combination of frictional heating and strain causes dynamic recrystallization ─Adiabatic heating  Creates a very fine grain microstructure ─Low distortion ─Excellent weld properties

Friction Stir Welding Variables  Essential FSW variables ─Vertical (Forge) force, F z ─RPM,  ─Travel (Traverse) speed, V f  Process forces ─Travel (Traverse) force, F x ─Cross (Transverse) force, F y ─Vertical (Forge) force, F z Ref: Arbegast, William J., "Week 2 Friction Stir Joining: Process Optimization." (2003).

Friction Stir Welding Local Clamp FSW Tool Main Spindle Fixturing

FSW Economics  FSW of Aluminum ─15% reduction in man-hour per ton rate in aluminum panel fabrication – Hydro Aluminum ─Total fabrication savings of 10% in shipbuilding - Fjellstrand ─60% cost savings on Delta II and IV rockets – Boeing ─400% improvement in cycle time for fabricating 25mm thick plates – General Dynamics Land Systems  FSW of Steel Pipeline ─Estimated cost savings ─Onshore construction, 7% ─Offshore construction (J-Lay), 25% -Kallee, S. W. (2010). Industrial Applications of Friction Stir Welding. In D. Lohwasser, & Z. Chen, Friction Stir Welding From Basics to Applications (pp ). Boca Raton: CRC Press. -Kumar, A., Fairchild, D. P., Macia, M., Anderson, T. D., Jin, H. W., Ayer, R.,... Mueller, R. R. (2011). Evaluation of Economic Incentives and Weld Properties for Welding Steel Pipelines Using Friction Stir Welding.Proceedings of the Twenty-first (2011) INternational Offshore and Polar Engineering Conference (pp ). Maui: ISOPE.

FSW of Steel Cost Model  Assumptions ─Plain carbon steel ─Simple butt joint configuration ─Use of EWI DuraStir™ tools ─Machine and fixturing purpose built for assumed application ─Range of thicknesses ─3, 6, 9, 12, 16, 19 mm ─Broken down in terms of cost/meter based upon weld length achievable each month

FSW Cost Summary Cost Summary Thickness 3.00 (mm)6.00 (mm)9.00 (mm)12.00 (mm)16.00 (mm)19.00 (mm) Production Costs: $246.31/m$307.24/m$373.45/m$444.94/m$531.46/m$613.51/m Fixed Costs: $18.12/m$21.44/m$27.94/m$28.31/m$40.52/m$53.20/m Variable Costs: $36.46/m$41.32/m$62.65/m$83.29/m$127.46/m$306.23/m Total Cost Per Meter: $300.88/m$370.00/m$464.05/m$556.55/m$699.44/m$972.94/m

Cladding

Introduction  Many process options exist for weld cladding and hardfacing  A number of factors should be considered when selecting a process: ─Desired deposition rate ─Required dilution level ─Welding position ─Component size/geometry ─Method of application ─Manual/semi-automatic ─Mechanized ─Automated ─Welder/operator skill ─Alloy/material to be deposited ─Equipment cost

Available Processes for Surfacing Include  Thermal spray  Resistance cladding  Laser cladding  Gas tungsten arc welding (GTAW)  Plasma arc welding (PAW)  Gas metal arc welding (GMAW)  Submerged arc welding (SAW) ─Single and multi-wire SAW ─Submerged arc strip cladding ─Electroslag strip cladding  Explosion welding

Resistance Cladding  Uses Simple off the shelf sheet material and may use interlayers to make a fusion type weld between CRA and Pipe  Can make the clad weld in one pass  Uses sheet metal consumables which are much lower cost than wire consumables  Post weld surface finish should meet customer requirements  No dilution of base metal into CRA surface

Resistance Cladding

Current Cladding Techiques  Explosive Welding $$$$ ─ Requires post cladding longitudinal seam weld which impacts fatigue  Roll Bonding ─ Requires post clad longitudinal seam weld  GMAW / GTAW / SAW welding ─ Processing time intensive with inspectability issues  Liner Expansion (lowest cost) ─ Risk of liner buckling is concerning to customers during installation or dynamic lines

Resistance Cladding  Cost comparison

Tandem GMAW Bonus Material

Why Use Tandem GMAW?  Improve Productivity and Quality ─ Increased deposition rates ─ Faster travel speeds ─ Maintain or improve overall weld quality, gap filling capability Deposition rate (lbs/hr) Image courtesy of Lincoln Electric

Example  5.25-in.-thick test joint  0.5-in.wide groove  2° included angle  Travel speed: 15 ipm  Heat input: 46 kJ/in.  Single bead per layer  27 passes required to fill 4.5 in.  Fill height per pass ≈ 0.17 in.  Clean UT results