© Siemens AG 2012.

Laser Metal Deposition for Maintenance, Repair and

Overhaul at Siemens Fossil Power Generation

AKL - International Laser Technology Congress

Dr. D. Thomaidis, Dr. M. Ott, N. Arjakine,

Dr. G. Bostanjoglo

Aachen Mai 9th, 2012

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© Siemens AG 2012

Content

Introduction

Examples of advanced repair welding technology at Siemens AG

Laser cladding

Laser build-up welding

Summary

Content

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HealthcareEnergyIndustry Infrastructure & Cities

Oil & Gas

Fossil Power Gen.

Wind Power

Solar & Hydro

Energy Service

Power Transmission

Generators (E F PR GN)

Sales (E F PR S)

Products (E F PR)

Steam Turbines (E F PR SU)

System Integration (E F PR SI)

Feeder Plants (E F PR FP)

Sector

Division

Business Unit

Business Segment Gas Turbines (E F PR GT)

Siemens Energy Sector – New set-up for the future requirements of the market

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Siemens Energy Sector – New set-up for the future requirements of the market

Solar & Hydro(E X)

Power Transmission

(E T)

Oil & Gas

(E O)

Fossil PowerGeneration

(E F)

Wind Power(E W)

Energy Service

(E S)

Energy products and solutions – in 6 DivisionsProducts and solutions – in 6 Divisions

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50 Hz 292 MW

168 MW

375 MW

60 Hz

274 MW

208 MW

113 MW

SGT5-8000H

SGT5-4000F

SGT5-2000E

SGT6-2000E

SGT6-5000F

SGT6-8000H

Siemens large-scale gas turbines

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Slide 6

Products Business Unit – Innovation highlight: Siemens SGT-8000H series gas

turbine

Strong fluctuations in grid demand and feed-inrequire higher operational flexibility

The focus on “clean energy” is driving the demand for more efficient power generation solutions

The high-tech class is the fastest growing gas turbine market segment of the future

Market requirements

Siemens SGT-8000H series solution Reduction of emissions per kWh generated Higher efficiency: over 60% in combined cycle

operation Maximum operational flexibility due to highest part-

load efficiency and highest ramp rates

Proven rotor design, free radial thermal expansion andcentral tie bolt

Evolutionary 3D compressorblades

Improved combustionsystem forUltra-low NOx

High load flexibility through improvedblade cooling system

Four-stageturbine

Customer benefits Lower investment costs per kW Lower lifecycle costs High reliability and availability Short start-up times and high operational flexibility

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Development tendency of materials for increased turbine inlet temperature in gas

turbines

1950 1965 1980 1995 2010

800

950

1100

1250

1500

T°C1800

2025

Turb

ine

Inle

t Te

mpe

ratu

re

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Prager’s plot of weldability versus Al and Ti content - Cracking Categories

Types of cracking which may occur during and after welding

include:

• Solidification cracking (SC)

• Liquation cracking (LC)

• Ductility dip cracking (DDC)

• Reheat (strain age) cracking (RHC)

For example: a) - SC and b) - LC

a b

1 2 3 4 5 6

1

2

3

4

5

6

Titanium, %Alu

min

ium

, %

Inconel 718

Udimet 600 Astroloy

IN 100

Udimet 500

Rene 41

Difficult To Weld

Readily Weldable

Source: Journal

of Materials Engineering and

Performance

Volume 6(5)

October 1997

Rene 80

IN738

IN 939

IN 625

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Solutions to minimize cracking caused by the welding process

Lower heat input during

welding

Beam Welding

Micro Plasma Powder Welding

Improvement of welding parameters

Heat treatment

Welding filler materials Use of ductile welding filler materials

Pre weld H/T

(solutioning / overaging)

Post weld H/T

Hotbox – welding

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Solutions to minimize cracking caused by the welding process

Development of a LMD process at room temperature for highly γ’-strengthened nickel-base superalloys with

a γ’-strengthened filler material to create material properties for a structural repair.

Development of process parameters for LMD with reduced heat affected zone in the base material to avoid

negative impact on the substrate microstructure.

Development of a numerical model and resulting process parameters for LMD to adjust the cooling rates

during solidification

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Transitions wear at the MC

Gap of only 3,5-4mm at the transitions

Casing deformation during operation

Hammering and abrasion occurs

Laser hard facing of the transitions

Increasing the wear resistance

Repairable by TIG welding on site

Field testing ongoing

Hard facing technology – Demand and Solution

Hard facing of

the cooling air ring

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• Hard facing by laser welding for production

• Field test shows good results

• Application for Siemens patent

• Replacement of Parts possible

during scheduled Major Outages

Product improvement available

For New Part and Service!

Status: Hard facing Solution

20mmProduction Laser weld

Testing in GT

Hard faced spots

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Blade tip restoration by

Manual TIG-welding Laser powder welding

multiple layers

small amount of overlaying

material

reduced re-contouring effort

low process time

few layers

remarkable amount of overlaying

material

respective re-contouring effort

high process time

m-TIG vs. Laser Powder Welding

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m-TIG vs. Laser Powder Welding

Improved Quality

HAZ:

up to 0.5 mm

visible 3 mm

respective high

heat input

risk of crack

introduction &

propagation

HAZ: up to 0.15 mm

reduced heat input

Laser process is more robust, faster and offers better quality

Laser powder weldingManual TIG-welding

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Further Laser Powder Applications

…rubbing marks at stationary blades…

Repair of…

…and at guide ring

Combination of Laser and

Hot-Box

Possibility of high-strength matching filler

welding

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Summary

The low weldability of advanced GT materials represents a significant challenge.

The combination of advanced welding technologies like LMD with in-depth materials knowledge and their

behavior during welding allow the repair of these material systems.

The ability to perform such repair of GT components reduces life cycle costs and repair lead time, lowers

the scrap rate and makes repair and refurbishment more cost effective for gas turbine owners.

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Thank you for your attention – any questions?

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