Failure Analysis on a Broken ICE3 Railway...

Failure Analysis on Broken Railway Axle ICE3

BAM-V.3, Klinger et. al. ESIS TC24 Railway Structures, 11. Oct. 2010

Failure Analysis on a Broken ICE3 Railway Axle

Interdisciplinary

Approach

Federal Institute for

Materials Research and TestingWorking

Group „Failure

Analysis“

with

results

from

divisionsV.3, V.1, V.2, VI.1, VI.3, VIII.3, VIII.4 …

C. Klinger

D. Bettge, R. Häcker, T. Heckel, D. Gohlke, D. Klingbeil …

Bundesanstalt für Materialforschung und -prüfung



Customers

for

WG „Failure

Analysis“

•

Police, State Attorney,

Court of Justice

•

Government Ministry

•

Public authorities

for

railways, motor

vehicules

and ships

•

Industry

•

Insurance

•

Standardisation

bodies

•

The

Media



Cases

of damage

from

different technological

areas

EXAMPLES

•

Mechanical

and Plant Engineering: Boilers…

•

Transportation: Railway,

Ships, Airplanes, Vehicles

•

Transportation

of dangerous

goods: Containers…

•

Gas Safety

Engineering: Valves

•

Medical

Engineering: Implants

•

Structural

Engineering: Overhead

Eletrical

Power Towers


BAM-V.3, Klinger et. al. ESIS TC24 Railway Structures, 11. Oct. 2010 Folie 4

Interdisciplinary

Failure

Analysis for

complex

accidents

Numerical Analysis

Non Destructive Testing

Materials Testing

Service loading

fatigue

Corrosion

mechanical

engineering Microstructure



Derailment

of ICE3 at Köln Hbf on 9. July

2008

ICE 518, Hohenzollern Bridge [press photo]



Derailing

of a Motor Wheelset

Bild ICE3 auf der Hohenzollernbrücke hierher

[press photo]



ICE3: Failure

of a Motor Axle

Quelle: ARD, Monitor 2008-

11-06



Task

given

by

state

attorney

Köln, July

2008:

Accident

Analysis of the

derailment

of ICE 518

•

Material-, Production-

or

Maintenance

Defects•

Deficiencies

of the

vehicle

•

Compliance

with

the

rules•

Root

Cause for

failure

Senior Prosecutor

Köln Februray

2010: authorisation

for

„open

discourse

within

scientific

associations“



Position of broken

wheelset

within

the

train, fracture

surfaces

fracture

surface

FA, axle, gear

box, wheel

AWheel B, fracture

surface

FB

403 510

2. Klasse

403 610

2. Klasse

403 810

2. Klasse

403 710

2. Klasse

direction

of train

Bridgemain

station

Köln

(sketch

DB AG)

(press photo)

within

Bogie

-

trailing

wheelset

heading

for

Köln; -

leading

wheelset

heading

for

Dortmund



Broken wheelset

with

gearbox

coupling

gearbox axle

bearing

wheel

discside

A

wheel

discside

B

location

of fracture

freefit



Increased

Loading

on the

axle? Inspection

of components

in the

motor

bogie

Air spring

damper

lever

primary

springReplacement: Trailing

Wheelset

motorsupport

bogie

frame

coupling

brake

damage



Damage

on the

bogie

frame

(corner

2R): smeared

material caused

by

wheel

contact

rotation direction

of wheel

=> Contact

wheel

–

frame

while

train

heading

to Köln



Mechanized ultrasonic inspection of axles•

Damaged

axle: areas

with

three-centre

curves

and hutches

•

Comparative

specimen: Area

of fracture

and and

areas

with

three-centre

curves

and hutches

side

A(gear)

side

B

center

inner surface

outersurface



UT testings

of broken

wheelset

axle

# …419 before

failure

•

UT testing

on volumetric

defects

by

manufacturer: recording

level

set to 1 mm DSR (Disk Shaped

Reflector)

=> no indications

•

UT testing

on horizontal oriented

crack

type

defects

by


level

set

to 2 mm SCD (saw

cut

depth)

=> no crack-type

indications•

UT in-service

inspection

on crack

type

defects

(outer

surface):

recording

level

set

to approx. 2 mm SCD [reported

by

DB] UT testing

with

HPS unit

by

DB AG:

RSW 2660419 on 2008/03/27 => no crack-type

indications

Used

standards

and proceedings

for

UT testing: Richtlinie ZfP-US-Radsatz-Laengsbohr-907.0201-neu

US-Prüfung Tz406-907.9043



UT testings

of broken

wheelset

axle

# …419 at BAM

•

Manual operated

mechanized

UT testing

on both

parts

of broken wheelset

axle

[recording

level

approx. 1 mm SCD]: => no crack-type

indications!

•

Manual operated

mechanized

UT testing

on axle

from

same

batch [recording

level

approx. 1 mm SCD]: => no crack-type

indications!

•

Manual UT testing

close

to crack

with

focus

on parallel cracks => no crack-type

indications!

•

Manual MT testing

close

to crack: => no crack

type

indications!



Material investigations (destructive)

•

Separation of the

broken

wheelset•

Mechanical

tests

•

tensile

test•

impact

test

•

Chemical analysis•

Fractography

•

Metallography•

Identification

of purity


BAM-V.3, Klinger et. al. ESIS TC24 Railway Structures, 11. Oct. 2010 17

Separation of the

broken wheelset

oxygen

cutting

of the

axle

Cutting

of axle

journal, side

Awheel

disc: force out of the

axle

Side A

side

A

side

B



Part of the

axleFit Fit of wheel Fit of gear

box Free fit

Sampling

Side A Side B



Driven

wheelset

axles

ICE3•

Realisation: high strength

steel

allows

for

higher

stresses

•

Disadvantage: crack

growth rates

for

steel

are

unaffected

by

material grade:

•

higher

operation

stresses

will lead

to increased

defect

growth rates:•

10% increase

in stress level

reduces

the

inspection

interval

by

200 …

300% [Benyon2001]

•

[Benyon, J.A. and Watson, A.S. (2001): The use of Monte-Carlo analysis to increase axle inspection interval. Proceedings of the 13th Int. Wheelset

Congress , Rome, Italy]



Mechanical

tests: sampling

Different standards

for

product

and material:•

E_EN 13261:1998 Wheelsets

, Product

requirements•

EN 10083-1:1996 Steels for quenching and tempering, General technical

delivery conditions

Specimens

forEN 10083-1 EN 13261

Tensile

test quantity: 1Distance to surface

12,5 mm

min. ∅

10 mmquantity: 3between

Ri

und Ra

Impact test ISO-V-specimen

quantity: 3 , axialDistance to surface

12,5 mm

ISO-U-specimenquantity: 9+9 , axial and across,between

Ri

und Ra

Chemical analysis without

requirements



Tensile

Tests



Mechanical

tests

ReH

in MPa

Rm

in MPa A in % Z in %

K in J

Required

values

„Techn. Spezifikation /Liefervorschrift für Radsätze ICE 3“

03/97

900…1050

EN 10083-1:1996 for

100mm < d < 160 mmfor

160 mm < d < 250 mm≥

700≥

600900…1100800…950

≥

12≥

13≥

55≥

55KV

≥

45KV

≥

45

Actualvalues

Test results 889 982 17...30 67 KV = 109

KU long. = 56 / 57 / 54trans. = 49 / 50 / 44

„similar

to EN 10083-1“

Strength, ductility, toughness

and impact

energy

are

conform

to the requirements

of EN 10083.

comparison

of requirements

and results

EN 10083-1:1996 Vergütungsstähle, Technische Lieferbedingungen für Edelstähle

outs

ide

mid

dle

insid

e

Auße

n+In

nen

Mitt

e



Gradient of material properties

across

the

cross section?•

Sampling

and test of ISO-V-specimens

out of the

area

of crack

inititiation•

Axial specimen

Location

of specimen

Mean

valuearea

of crack

inititiation 110 JOpposite

to the

area

of crack

initiation109 J

No gradient

in m. p. detectable



Fractographic

Examination

•

Allocation

of the

fracture

surfaces

to each

other

•

Fracture

mechanism

(e.g. forced

fracture

or

fatigue

fracture)

•

Allocation

of crack

origin

•

Amounts

of fatigue

fracture

and residual fracture

•

Further

details

in the

fracture

surface

•

=> Description

of cracking

process



Fractography•

Removing

the

fracture

surfaces

Fracture

surface

FA Fracure

surface

FB



FA•

Marking

of visible

beachmarks

an other

features

visible

beach

mark

supposed

beach

mark

crack

origin

max

. WS

FA

min

. WS

FA

„twirl“

residual fracture?

•

Crack origin

is

extrapolated



FB

visible

beach

mark

supposed

beach

mark

min

. WS

FB

max

. WS

FB

„groove“

residual fracture?

•

Marking

of visible

beachmarks

an other

features



Allocation FA to FB

•

Image of FA with

features

of FA (yellow) and FB (green, mirrored)

„twirl“/“groove“

residual fracture

min.

WS

FB

max

. WS

FB

max

. WS

FA

min

. WS

FA



Fatigue Crack•

Confirmation

of the

fatigue

fracture: beachmarks

(visual) and fatigue

striations

(SEM)

crack

origin

20 mm



Residual Fracture on FB

rubbed

fracture

surfaceductile

forced

fractue

„groove“

SEM: forced

fracure

10 mm

50 μm



Crack Propagation•

Illustration of the

fracture

mechanism•

Estimation

of the

area

fraction

of the

residual fracture

Crack origin

Residual fracture

minimum

maximum



Crack Propagation

Cracking

sequence:1)

Fatigue

crack,

propagation

on both sides

of the

hole

2)

Small residual fracture3)

Rubbing of the fracture surfaces

schematic

1) 1)

1)1)

1)

2)3)

3)3)

3)

3)

3)

3)

3)

3)

3)3)3)

3)

3)



Cutting FA

Cutting

Fractography

Crack origin

SEM

SEM

SEM

FA-01FA-02

FA-03

Cutting

Metallography

FA-01-01FA-01-02

FA-01-04FA-01-05

FA-01-03

CT



“Secondary Pattern”Superposition of 3

features:•

Primary: fatigue

crack•

Secundary: line

pattern•

Tertiary: rubbed fatigue

crack

rubbed

line

patterns

rubb

ed

rubbedfatigue

crack



Interpretation of Secondary PatternMechanism

(hypothesis)

•

Clearly

defined

torsional

movement

of FB around

the

„twirl/groove“

site

just before

final fracture

of the

axle•

secondary

line

pattern

by

imprinting

the

edge

of FA into

FB•

then

final fracture

•

Estimation

of the

driven

distance during

generation

of the

secondary

line

patterns: Wheel diameter

920 mm, 80 lines

=> 230 m driven

distance•

Final fracture

somewhere

before

Köln main

station



Results Fractography

•

Final fracture

of the

axle

before

Köln Hbf

•

Fatigue

crack

caused

by

rotational

bending

•

Residual fracture

about

1/5th of fracture

surface

•

Crack origin

Site localised, but

not

evaluable

•

Succesful

allocation

of the

fracture

surfaces

to each

other



•

Baumann print

of disc

SQ•

Result: similar

to images

in UIC 811-1•

Rating: OK

Investigation of segregation



•

Disc SQ polished•

Result: coarse

dendrites

near

the

crack

origin•

Rating: questionable

Dendrites



Hardness•

Polished

disc

SQB•

Methods: HV10 and HRC, 3 line

scans

each



0

50

100

150

200

250

300

350

0 10 20 30 40 50 60

Entfernung zum Außenrand in mm

Här

te in

HV1

0

Reihe 3 BruchausgangReihe 4Reihe 5

Hardness•

Result: no differences

between

crack

origin

an the

other

sectors•

Rating: OK

0

5

10

15

20

25

30

35

0 10 20 30 40 50 60

Entfernung zum Außenrand in mm

Här

te in

HR

C

Reihe 6, BruchausgangReihe 7Reihe 8



Microstructure•

Quenched

and tempered

with

Bainite•

Matching

the

target

state

cross section plain

section



Grain Size•

Target state: CEN draft

TL256/SC2/WG11:1997, grains

smaller

than

class

5 (62 μm)

•

Result: class

6/7 (30 μm) => OK



Metallographic Investigation

•

Macro Structure – OK•

Hardness

–

OK

•

Microstructure

–

OK•

Grain Size – OK

•

Surface

Roughness

–

OK

•

Purity

Level?



Micro CT Investigation of Crack Origin

Cube

containing

the

crack

origin (FA-01-02)



Investigation of Crack Origin•

NDT of volume around crack origin by Micro-

Computertomography

(µCT)

•

strong

secondary

deformations

after

final fracture

FA-01-02

1 cm

FA-01-02



Cutting Through the Crack Origin •

Cross section

of the

crack

origin•

=> highly

deformed

estimated

original shape

of the

crack

origin

region

-t

a

-r

a

r

CT model

of the

crack

origin



•

Cross section

through

the

crack

origin•

Recrystallisation

of the

surface

region

due

to overheating

base

structure

recystallisation

a

r

Deformation of the Fracture Surface



µCT Crack Origin•

Large indications

A1, A2 und A3: Inclusions?

•

Definition of coordinates

for

arget

preparation

A2

A3

A1

Dimensions

of the

indications:A1: 698

x 133

x 33

µmA2: 930

x 133

x 33

µmA3: 399

x 100

x 33

µm1 Voxel

~ 16µm³

(a

x r

x t)-t

a

-r

-t

a

-t

a

CT plane r

5 mm

CT-plane r



•

Confirmation: A1 is

an inclusion•

Some

more

inclusions

up to 40 µm are

visible-t

a

-r

Length

of inclusion

A1 perpendicular

to this

plane is

~700 μm!

-t

-r

corss

section

outer

surface

Metallographic Preparation of Indication A1



Examples of Inclusions

100 μm 100 μm

a

r

a

r

length

275 µmwidth

58 µm

length

350 µmwidth

30 µm

for

both

inclusions:length

and width

are

not

acceptable

-t

a

-r



Nonmetallic Inclusions•

Morphology

similar

type

„C“

according

to ISO 4967:1998 •

Chemical analysis

(EDX): oxides

and sulfides•

Rating: due

to casting

process

5: S, Ca, Al, Mn, O

6: Al, O, (Ca)

1: Al, O, Ca, Si

3: Al, O

10 μm-t

-r

5 μm

a

r



Nonmetallic Inclusions•

ISO 4967:1998

Type C acceptable up to length of 176 µm•

Rating

of the

big

inclusions

found: not

acceptable

a

r

length

550 µmwidth

30 µmtype

C 2,5e + unacceptable

width

-t

a

-r



Purity according to ISO 4967:1998 (E) Method A

near

crac

kor

igin

far a

way

Rating: Purity

level

is

not

acceptable

A: Sulfid-Typ B: Alu- Typ C: Silicat-Typ D/DS: Typ globulare Oxide

Einzelwerte, dicke Serie, maximal Summe B+C+D Zulässige Werte nach Entwurf CEN TL 256… Kategorie 1

A ≤ 1 Länge < 261 µm

B ≤ 1 Länge < 184 µm

C ≤ 1 Länge < 176 µm

D/DS ≤ 1 D: Anzahl < 9 DS: Durchmesser < 27 µm

B+C+D ≤ 2

Probe Messergebnisse zulässig/unzulässig

FA-01-02 A 1 Länge >127 µm bis ≤ 261 µm Dicke ≥ 2 µm bis ≤ 4 µm

(keine) C 2,5e Länge ≥510 bis <746 µm Dicke > 5 µm bis ≤ 12 µm

D 0,5e 1 bis 3 Einschlüsse im Messfeld Dicke ≥ 8 µm bis ≤ 13 µm

3

SQ(A)-01-03 A 1 e Länge >127 µm bis ≤ 261 µm Dicke ≥ 4 µm bis ≤12 µm

(keine) C 0,5 Länge >18 µm bis ≤ 76 Dicke ≥ 2 µm bis ≤ 5 µm

DS 2 einzelner Einschluss Ø > 38 bis ≤ 53 µm

2

SQ(A)-02-03 A 1 e Länge >127 µm bis ≤ 261 µm Dicke ≥ 4 µm bis ≤12 µm

(keine) C 0,5 Länge 18 µm bis ≤ 76 Dicke ≥ 2 µm bis ≤ 5 µm

DS 2 einzelner Einschluss Ø > 38 bis ≤ 53 µm

2

SME-01-03 A 1 Länge >127 µm bis ≤261 µm Dicke ≥ 2 µm bis ≤4 µm

(keine) C 0,5 Länge 18 µm bis ≤ 76 Dicke ≥ 2 µm bis ≤ 5 µm

D 0,5 e 1 bis 3 Einschlüsse im Messfeld Dicke ≥ 8 µm bis ≤ 13 µm

0,5

SAE-01-03 A 1 Länge >127 µm bis ≤261 µm Dicke ≥ 2 µm bis ≤4 µm

(keine) C 0,5 e Länge 18 µm bis ≤ 76 Dicke > 5 µm bis ≤12 µm

DS 1,5 einzelner Einschluss Ø > 27 bis ≤ 38 µm

2

TC



Inclusion at the Axle Surface•

Roughness

OK•

Disc with

fracture

surface

FB•

SEM investigation•

Rating: inclusion, Aluminum

oxide

a

t

EDX measurement:

Al, O



Using UT imersion

Technique for the detection of inhomogenities

and sizing of non-metal inclusions

Disc SQC

UT imersion

tank BAM-VIII.43



Accumulation of indications in a specific sector

side

A side

B

Combination

of sectorswith

relevant volumetric indications



Purity grade: Gap in standards •

Standard „Radsatzwelle für Hochgeschwindigkeitsverkehr“

Non-metal

inclusions

Type C up to

length

of 176 µm

accepted

•

NDT inspection

by


level

1 mm DSR

•

In-service

inspection

by

operator: recording

level

2 mm SCD



Results: Purity of axle material•

Nonmetallic

Inclusions

of unacceptable

size

detected

•close

to the

surface

and•on the

surface

in the

recess

•close

to the

crack

initiation

area• in a sector

over

the

whole

lenght

of the

axle

•

Requirements

on Puritiy

are

not

fullfilled

•

Nonmetallic

Inclusion

initiated

fatigue

crack?



Fatigue Crack Initiation at very high cycles•

Failure

1977: crankshaft

for

6 cylinders,

journal

diameter

200 mm, thickness

of crank

arm 58,5

mm•

fatigue

fracture

at 3. crankshaft

journal

after

~ 6 ·

107 cycles

[BAM Test Report 1.2/11323]

Fatigue

crack

start



Crankshaft

failure•

Material 34CrMo4, inductiv

hardened

•

Initiation ~ 0,5 mm below

the

surface

~1,5mm

beach

marks



Initiation of fatigue

crack

at nonmetallic

inclusion•

nonmetallic

inclusion

Al, Si, Ca, Mn, 0 : slag

•

bad position

in the

area

of maximum

stress



Hypothesis: Root

causes

for

axle

fractureConjunction

of following

contributing

factors:

•

nonmetallic

inclusions

of unacceptable

size

from

production

•

Large nonmetallic

inclusions

have

not

been

detected

after:

•

Casting: metallographic

examination

of the

purity

•

Forging: Ultrasonic

Testing

for

inner defects

with

vertical

probe according

to TL

918

275 A (registration

threshold: 1

mm circular

disk

shaped

reflector)

•

Wheelset

assembly: Ultrasonic

Testing

for

transverse

defects•

Very

high cycles

in service

3 ●

106

km ~ 109

cycles

•

highly

utilised

axle

=> Initiation of fatigue

crack

in the

recess

(three-center

curve)•

fast crack

propagation

due

to high stresses

•

Fatigue

crack

was not

detected

early

enough:•

Registration

threshold

for

UT (~ 2 mm saw

cut

depht) was too

high OR

•

Inspection

interval

(until

July

2008: 300.000 km) was too

long



Immediate Measures: substancial

reduction

of UT-inspection

interval

•

EBA 10.7.2008: UT of all axles

made

of 34CrNiMo6

60.000 km instead

of 300.000 km

•

currently: 30.000 km



Consequences

17.7.2009

•

Abatement

of the

investigations

by

state

attorney

Köln:•

the

employees

of Deutsche Bahn can

not

be

prosecuted

… The

impurity

of the

material was not

visible

for

them…•

The

manufactures

of the

axle

may

not

be

accused…

•

[Spiegel online, FTD.de, Handelsblatt, WDR.de, AN online, Berliner Zeitung, taz.de, …17.7.2009 …]



Consequences: Exchange of all motor

axles•

… Deutsche Bahn and manufacturers

Siemens and

Bombardier aggree: …

all ICE3 motor

axles

will be changed

…

•

…manufacturers

designing

new

axles, …

testing, … approval

by

EBA

•

…two

to three

years

until

all 70 ICEs will run

on new

axles.•

… increase

of inspection

intervals.

•

costs

due

to the

problem

with

the

axles

~ 350 Million Euro.“

•

[ARD.de

12.10.2009 and Kölnische Rundschau 13.10.2009]



Thank

You

very

much

for

your

Attention

Failure Analysis on a Broken ICE3 Railway...

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