Economics of Advanced
Welding Techniques
March 28, 2013
Stephen Levesque
Director, EWI Nuclear Fabrication Center
Email: slevesque@ewi.org
Office: 614-688-5183
Mobile: 614-284-5426
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 reestablishment 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
0.005-in. gap
0.010-in. gap
0.015-in. gap
General Terminology

Autogenous Laser Welding
Laser Beam
LaserInduced
Vapor
Plume
Shielding
gas
Liquid
Weld
Pool
Laser
Keyhole
or
Vapor
Cavity
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
GMAW Torch
Laser Beam
Hybrid Terminology

The HLAW process can be used in two orientations:
“Laser-Leading” HLAW
“Arc-Leading” HLAW
Laser Tube Sheet Welding
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
$550,000
$500,000
$450,000
$400,000
Estimated Cost

$350,000
$300,000
$250,000
$200,000
2kW Laser @ 50%
$150,000
Manual GTAW @ 50%
$100,000
Orbital GTAW @ 75%
$50,000
Robotic GTAW @ 80%
$0
0
20000
40000
60000
Number of Tubes
80000
100000
Laser Tube Sheet Welding
Containment Welding

Hybrid Laser-GMAW welding vs. Tandem GMAW vs.
Submerged Arc Welding
Productivity
For one weldment X long
Includes setup time
and weld time
"10" 50-in "10" 200-in
Parts
Parts
Hours

SAW
11
27
Tandem
8
18
HLAW
15
16
Cost Comparison
For one weldment X long
Equipment Cost
SAW
$55k
Tandem
$150k
HLAW
$950k
"10" 60-in "10" 200-in
Parts
Parts
Dollars

Includes setup
time/weld time
(@$75/hr) and filler
metal cost
SAW
$48k
$124k
Tandem
$38k
$84k
HLAW
$69k
$72k
Combined Comparison Data
200-in
Other Benefits

Peak Temperature Models showing reduction in heat
input
SAW
HLAW
GMAW-T
Distortion and Residual Stress
SAW
Tandem
HLAW
Friction Stir Welding
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
─ Travel (Traverse) force, Fx
─ Cross (Transverse) force, Fy
─ Vertical (Forge) force, Fz
Ref: Arbegast, William J., "Week 2 Friction Stir Joining: Process Optimization." (2003).
Fz
Fx
Process forces

FF
xy x
FFyx
Vf
Fz

Vf
Fz
Fy


Fx Fy
Vf
─ Vertical (Forge) force, Fz
─ RPM, 
─ Travel (Traverse) speed, Vf

Essential FSW variables
Fz

Fx

VFfFz
z
Friction Stir Welding
Main Spindle
Fixturing
Local Clamp
FSW Tool
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. 118-163). 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. 460-467). 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:
Fixed Costs:
Variable Costs:
$246.31/m
$18.12/m
$36.46/m
$307.24/m
$21.44/m
$41.32/m
$373.45/m
$27.94/m
$62.65/m
$444.94/m
$28.31/m
$83.29/m
$531.46/m
$40.52/m
$127.46/m
$613.51/m
$53.20/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

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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 $$$$
─

Roll Bonding
─

Requires post clad longitudinal seam weld
GMAW / GTAW / SAW welding
─

Requires post cladding longitudinal seam weld which impacts
fatigue
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
Normalized Price Per Unit
RSEW Pipe
Roll Bonded Pipe
Expanded Liner Pipe
CRA Piping
0
20
40
60
80
100
120
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
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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