Advanced Materials and Laser Advanced Materials and Laser based based Welding TechnologiesWelding Technologies

Automotive sectorIndustry trends

Need to reduce CO2 emissions in exhaust gases to fight global warming

Improvement of combustion efficiency Reduction of vehicle weight Reduction of loss of efficiency through friction

Materials development Welding Processes

Materials development Welding Processes

• High tensile strength steel materials- Advanced High Strength Steels (AHSS), Ultra High Strength Steels (UHSS)

• Galvanised steel• Aluminium• Magnesium• Composites

Advanced materials

Trend towards light-weight design is widely established Steels with very high ultimate tensile strength increasingly applied

Trend towards light-weight design is widely established Steels with very high ultimate tensile strength increasingly applied

5 out of 38 Advanced Transportation Tech Projects of US DoE (Sept 2013)

• Oak Ridge National Laboratory - Body-in-white Joining of Aluminum to Advanced High Strength Steel at Prototype Scale: - solid-state spot joining technology

• Johns Hopkins University - heat-generating foils to provide strong and stable bonds between aluminum alloys, magnesium alloys and steels.

• Oak Ridge National Laboratory - laser-assisted joining of aluminum and carbon fiber components

• The Ohio State University - Vapor-assisted collision welding of dissimilar metals.

• Michigan State University, Composite Vehicle Research Center - bonding, reparability and reassembly of dissimilar materials using thermoplastic adhesives

Some candidate components

4

Aluminium

Steel

Plastic

Aluminium outer skin – Steel innersupport of roof; closures such asdoors, bonnet and hood

Reinforced plasticfloor sections –Aluminium bodyframe

Reinforced plasticsections – to steelpillars and sidemembers

Multi-Materials Joining for Lightweighting(MultiJoin) Project being implemented in India with support of

Technology Development Board

aluminum

Robotic CMT weld brazed prototype

“MULTIJOIN” Project: Demonstrator assembly (2 m X 1m)

Useable for joining Steel/Aluminium, Steel/Steel and Aluminium/Aluminium Car body: Mass reduction up to 26% (AUDI) through mixed materials and smaller

flanges Adapted joining configurations

Overlap Flange

Al StAl St Al St

Short cycle times through high brazing speed (4 m/min) Flexible seam geometries by using a robot for laseroptic and wire feed Systems for Quality assurance available (SmartRay 3D for surface porosity,

undercut, geometry)

Laser Brazing

Automotive sectorAdvanced High Strength Steels (AHSS)

Microhardness Mapping: Local hardness variation and HAZ Softening

Static Tensile Failure Location Correlatesto HAZ Softening Region

*Zhili Feng, Oak Ridge National Laboratory

Automotive sectorLaser welding of Advanced High Strength Steels (AHSS)

Tensile strength Formability

Fully penetrating butt welds could be achieved at 5-8m/min, with 4kW of laser power and a 0.6mm diameter laser spot, depending on thickness. welding speed could be increased to 10-17m/min for the same laser power when a 0.4mm diameter laser spot was used.

Fully penetrating lap welds could be achieved in 0.8-1.5mm thickness at 2.5-6.5m/min with 4kW of laser power and a 0.6mm diameter laser spot. welding speed could be increased by 40% and 200-700% respectively, depending on thickness of steels, when 0.4 and 0.2mm diameter laser spots were used.

Tensile strength of butt welds in a range of steels produced with 4kW of laser power and a 0.6mm diameter spot *Steve Shi, Steve Westgate, TWI Ltd

Laser processing of AHSS

• Use of Advanced High Strength Steels– Hard cut edges

– Soft weld heat affected zones

• Solution a hybrid laser beam source, fiber laser for cutting & joining and diode laser for local heat treatment

Source: ILT Aachen

Power- NuclearEvolution of four generations of ferritic steels (Viswanathan and Bakker,2000)

• Modified 9Cr-1Mo Steel- High temperature components of fossil-fired power plants, steam generators of nuclear power plants

• Oxide dispersion strengthened (ODS) ferritic steels -clad tube material for oxide fuels, better creep properties up to 700°C

• Reduced Activation Ferritic-Martensitic Steels- candidate structural materials for TBM to be installed in the ITER Fusion Reactor

Trends of welding processes for nuclear power plant (Courtesy: Satoru Asai)

Power - Nuclear

Power- Thermal

Ratio change of high temperature materials with steam parameters development

Steam parameters development of coal fired power plants

Problems in fusion joining of Ni based super alloys

• Liquation cracking at grain boundary in PMZ• Sluggish nature of molten pool• Microfissuring in reheat zones of multipass welds

Bead on Plate welding trials

Mount Id

Laser power (kW)

Proc speed

(m/min)

Wire feed

(m/min)

Shieldinggas

INLHW-1

3.5 1 8He:Ar=80:20

INLHW-2

3.5 1 10He:Ar=80:20

INLHW-3

3.5 1 8 He=100%

INLHW-4

3.5 1 10 He=100%

Laser hybrid BOP welding of 10 mm thick IN 617 Super Alloy

LHW-1 LHW-2 LHW-3 LHW-4

Hardness survey across the weldHardness survey across the weld Hardness survey along the weldHardness survey along the weld

SEM images of LHW-3 FZ, HAZ & Laser SEM images of LHW-3 FZ, HAZ & Laser

SEM images of LHW-4 FZ, HAZ & Laser SEM images of LHW-4 FZ, HAZ & Laser

MIG-FZPrecipitate coarsening

Laser-FZ

MIG-FZ Precipitate coarsening Laser-FZ

MIG Fusion zone MIG-HAZ

• EDS images of LHW-3 indicate enrichment of FZ dendriticboundary & HAZ coarsened precipitate with Mo

C Ni Co Mo Ti Al Fe

0.01 18 7.75 4.9 0.40 0.10 Bal

As receivedsolution annealed at 820°C

very low C, tough and ductile Fe-Ni martensitic matrix

Aged480 °C for 3 h

fine, coherent intermetallic precipitates Ni3Mo, Ni3Ti,

Rocket motor casing

Microstructure

Composition (wt%)

Properties• High strength and high strength-to-

weight ratio• High notched strength• Maintains high strength up to at least

350°C• High impact toughness and plane strain

fracture toughness• Excellent weldability either in the

annealed or aged conditions. Pre- heat not required.

• Good machinability.• Good castability.

High Fracture Toughness

KIC = 120 MPa √m

Ultra High StrengthUTS = 1800 MPa

Rocket motor cases, cryogenic missiles, submarine hulls, landing gears, tooling and machinery

Applications

Defence

Defence

Laser- GMAW hybrid welding process set up

Laser- MIG hybrid welding process of 10mm thick Maraging Steel plates

Macrostructures

Single pass hybrid weld 3 pass MIG weld

Process Fusion zone area (sq.mm)

Eyebrow zone width from top to bottom

of bead (mm)Hybrid 34.5 0.6 to 1.2

MIG 108.4 2

Defence

Treatment 0.2% YS MPa

UTS, MPa % El Fracture location

Base metal as-received 862 970 18Base metal Aged 1735

169017501850

10

LHW as welded 929817

980930

14 Base metal

MIG as welded 1035911

10601056

14 Base metal

LHW PWHT 15901643

17511753

23

Weld

MIG PWHT 15751650

17551746

34.1

Weld

Tensile properties of M250 plate in different conditions

AerospaceAl-Li alloys

Commercial Aluminum-Lithium Alloys

Weldalite 049 Cu - 5.4, Li - 1.3, Ag - 0.4, Mg - 0.4, Zr - 0.14Alloy 2090 Cu - 2.7, Li - 2.2, Ag - 0.4, Zr - 0.12Alloy 2091 Cu - 2.1, Li - 2.0, Zr - 0.10Alloy 8090 Li - 2.45, Zr - 0.12, Cu - 1.3, Mg - 0.95

http://aluminumlithium.com/

Oil and Gas

Emerging technologiesHigh-Strength Steel Line Pipe: The use of higher strength steel requires less wall thickness for a given pipeline design or higher operating pressures for a pipeline design of a given wall thickness.Hybrid Welding Process: High efficiency lasers, which are becoming increasingly available, may make the use of hybrid welding processes feasible in the field. These processes are much more productive/less labour intensive than even the most advanced mechanised welding systems. Seam tracking will be an integral part of this technology since the welding speeds are high.

The offshore oil and gas industry is moving into deeper waters. Several issues arise:• The pipe wall thickness needs to be increased to resist hydrostatic collapse.• The pipelines may have to be laid by J-lay, instead of the more conventional S-lay

method to reduce the weight supported by the laybarge.• The hydrocarbons are higher pressure and temperature and often containing a higher

concentration of acid gases making the fluids more corrosive. In J-lay it is generally only possible to have a single welding station. Presently automatic gas welding is used but this has limitations.

Higher Higher Strength Strength MaterialsMaterials

More More Corrosive Corrosive

EnvironmentEnvironment

Higher well Higher well head head

pressurespressures

Welding Welding ChallengesChallenges

Shipbuilding

Laser technology – A revolution in shipbuilding

• Combining laser cutting and laser welding in one production line, along with complex clamping technology that renders exact pre-positioning and tack-welding of components unnecessary.

• Automating the precision manufacture of shipbuilding panels with considerably less thermal distortion than when using conventional joining methods.

• A new approach to designing steel ship internal structures from modular, standardised, precision steel subassemblies, referred to as parts families.

Joining Non-traditional Materials: • There is a need for increased performance (e.g. speed and manoeuvrability) and this is

driving the requirement to reduce ship weight. • This results in the use of non-traditional materials including non-metallic composites,

high-strength steel, aluminium, and titanium. • There are needs for materials joining processes for these materials and processes to

join dissimilar combinations of these materials.

Industrial Sectors

Material challenges Auto-genouslaser

Laser-arc hybrid

Laser hot/cold wire

Laser brazing

Laserspot

Laser remote

Laser metal-plastic

Automotive• AHSS• Multi-material design

Aerospace/ Defence

• Al-Li alloys• Composites• Maraging steels• Ti- alloys

Nuclear• Fusion- RAFMS• ODS

-

Thermal• AUSC- Ni based alloys

Oil & gas• 13Cr-4Ni Martensitic

S.S• “Super Martensitic S.S”

Shipbuilding•High-alloy steel-

distortion control

Laser based joining processes in different industrial sectors

Thanks for your attention

Email: gp@arci.res.in; director@arci.res.in