Journal of Electrical Engineering 3 (2015) 176-186 doi: 10.17265/2328-2223/2015.04.003

Laser Beam Welding of Alloyed Ultra-High Strength

Steels

Stefan Lindner1, Martin Dahmen2 and Benjamin Gerhards3

1. Outokumpu Nirosta GmbH, Krefeld Research Centre, Krefeld 47807, Germany

2. Fraunhofer Institute for Laser Technology, Aachen 52074, Germany

3. RWTH Aachen University ISF Welding and Joining Institute, Aachen 52062, Germany

Abstract: Stricter regulations for automotive car body engineering in point of CO2 emissions and safety requirements demand the application of ultra-high strength materials for lightweight constructions. But components manufactured with new materials need established, cost-efficient and their benefits supporting production processes. One high potential process is laser beam welding with its high welding speed, enormous flexibility, low thermal distortion and slim weld shape. The combination of new materials on the one side, and challenging welding methods on the other side, makes a good understanding for the joining process as well as for the behavior of the base materials during the heat input necessary to create constructions which exploit the full lightweight potential and fulfill the extensive requirements. The following paper contributes to the safety applying of new materials into the car body manufacturing process by giving laser joining recommendations for a verified weldability. Key words: Laser beam welding, chromium-manganese steels, ultra-high strength, press-hardening, lightweight, crash performance.

1. Motivation

The automotive engineering was characterized over

the last decades by a continuous increase of the car

body weight [1]. Different passenger advantages like

entertainment systems, passenger comfort, but also

electronic assistance systems to increase the active

passenger safety are responsible for this movement. At

the same time the worldwide regulations [2] demand a

continuous reduction of the CO2 emissions. These

contrary-seemed construction targets for automotive

engineers enforce new lightweight design possibilities.

One way to reach this approach is the application of

new high-strength materials which fulfill the

requirements in a cost-efficient way with a high

processability. Outokumpu Nirosta developed and

established a new material group called Forta H-series

with ultra-high strength properties for different

forming operations like cold-forming or

Corresponding author: Stefan Lindner, M.Sc. (IWE),

research fields: joining technologies, automotive constructions and stainless steel metallurgy.

press-hardening (“hot-formig”). For every grade the

weldability is one of the key processes [3] to reach the

targets in the automotive manufacturing process.

2. Cold-Forming Materials

For the production way of cold-forming parts

Outokumpu Nirosta designed a new austenitic

manganese-chromium alloyed steel group (MnCr

steels). The material family comprises the Forta H500

and the worked-hardened Forta H800 and Forta H1000

whereby the numbers declares the yield strength. The

mechanical-technological values represent a well

aligned relation between a high strength and a very

good elongation which are shown in Fig. 1 and Table 1.

The MnCr steels have a face centred cubic (fcc) lattice

structure depending on the concerted relation of the

chosen alloying elements. The fully austenitic

microstructure will be maintained after forming,

deformation, and welding without forming martensite.

A specific balanced stacking fault energy results in

the described stable austenitic microstructure. At the

same time the conditions to avoid any kind of delayed

D DAVID PUBLISHING

Fig. 1 Value

Table 1 Mec

cracking are

hardening e

steels (or c

converts in

induced plas

hardening e

hardening w

in the micro

microstructu

2,000 MPa i

operation or

The alloy

austenite for

increase of

manganese

from the gen

[5]. The sec

which influe

in a positiv

homogeneity

chromium-o

es of the austen

chanical-techn

e fulfilled [4

effect of me

called CrNi

nto martensit

sticity), the ne

effect (twinn

works by build

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ure. As a resu

in the harden

r a crash situa

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rmer and cre

strength as w

has the effec

neration of ph

cond main a

ences the me

ve way [6],

y of the oth

oxid passivati

Laser Bea

nitic cold-form

nological value

4]. Instead of

etastable aus

steels), whe

te (TRIP =

ew MnCr ste

ning-induced

ding up more

eping at all ti

ult it is possib

ned material d

ation.

nt manganes

eates further

well as ductil

ct of prevent

hases sensitiv

lloying elem

echanical-tech

support the

her elements

ion layer on

am Welding o

ming H-grades

es of the austen

f the well-kn

stenitic stain

ere the auste

= transforma

eels use the TW

plasticity).

e and more tw

ime an austen

ble to reach o

during a form

se works as

benefits like

lity. Furtherm

ting the mat

ve to hot-crack

ment is chrom

hnological va

e solubility

and build u

the steel sur

of Alloyed Ult

in relation to o

nitic cold-formi

nown

nless

enite

ation

WIP

The

wins

nitic

over

ming

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more

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mium

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and

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abs

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ene

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mic

ra-High Stren

other construct

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ich is well-kn

delivered brig

ating because

rosion protec

gularities. W

ating on th

sivation laye

tection syste

pping. The p

injured dip

perties.

The MnCr

orption comb

e example Fi

al crash of a

rta H800 in a

file shows a

ergy absorptio

d forming zon

During the i

crostructure a

ngth Steels

tion materials.

nown from sta

ght and does

e of this n

ction layer. T

With applyin

he manufac

er presents

m even after

assivation lay

coating bec

steels featur

bined with a h

g. 2 illustrat

a square prof

a thickness of

a great formi

on combined

nes.

impact situa

and the TWI

.

ainless steels.

not need a f

natural and r

This fact avo

g a typical

tured comp

a very goo

r a lattice cu

yer avoids an

cause of its r

re a very h

high impact r

tes a dynami

file manufac

f 1.5 mm. As

ing behavior

d with crack-

ation, the fu

P hardening

177

The material

further (zinc)

repassivating

oids welding

cathodic dip

ponents, the

od corrosion

ut or a stone

n undercut of

repassivating

high energy

resistance. As

c high-speed

ctured with a

s a result the

r and a high

-free welding

ull austenitic

effect of the

7

l

)

g

g

p

e

n

e

f

g

y

s

d

a

e

h

g

c

178

Fig. 2 High-

Fig. 3 Resul

Forta H-seri

will harden i

high resistan

the impact e

the axial cra

Therefore

For the exam

to a press-h

MPa) that a

under retent

-speed axial cr

lting hardness

ies develop th

in relation to t

nce to the imp

energy. Fig.

ash from Fig.

e a high direc

mple of a b-pi

ardened steel

a thickness r

tion of the in

Laser Bea

rash of Forta H

after the xial-

heir full bene

the impact fo

pact simultan

3 illustrates

2.

t lightweight

llar it can be

l (22MnB5 w

reduction of

ntrusion level

am Welding o

H800.

crash of Forta

efit: The mat

rce and subte

neously absorb

the hardenin

potential res

shown in rela

with Rm ≈ 1

35% is poss

but with a m

of Alloyed Ult

a H800 .

erial

end a

bing

ng of

sults.

ation

,500

sible

more

duc

T

tran

form

grou

up

long

cha

H-s

exp

ra-High Stren

ctile and crack

The MnCr s

nsport applic

m complex p

up. It is poss

to 50% for

gitudinal bea

annels, tanks

series enable

ploiting so f

ngth Steels

k-free crash b

steels enable

ations becau

parts with an

sible to reach

r complex c

ams, wheel

or battery pa

e further con

far not used

behavior.

e further ligh

use of their p

n ultra-high s

a lightweigh

cold forming

houses, sea

acks. Moreov

nstructive lig

geometrical

htweight for

possibility to

strength steel

ht potential of

g parts like

at structures,

ver the Forta

ghtweight by

l degrees of

r

o

l

f

e

,

a

y

f

freedom. O

processes l

combination

decrease th

component s

general.

3. LaserCold-Form

In genera

welding in

Especially

welding spee

Fig. 4 Ducti

Fig. 5 Hard

Other design

like roll for

n with a la

he weight

stiffness as w

r Beam mable MnC

al, austenitic

similar as w

laser beam

ed and locally

ile behavior of

dness curve and

Laser Bea

n ways and

rming or hy

aser beam w

and increas

well as the pa

WeldabilCr Steels

MnCr steels

well as in d

processes w

y concentrate

f a laser beam w

d micrograph o

am Welding o

d manufactu

ydro-forming

welding pro

e the resul

assenger safet

lity of

s are suitable

dissimilar we

with their h

ed heat input o

welded cross-t

of similar laser

of Alloyed Ult

uring

g in

ocess

lting

ty in

the

e for

elds.

high

offer

a gr

stee

F

stee

Mn

tran

and

test

L

beh

met

mea

dete

ensile-sample.

r-beam welded

ra-High Stren

reat potential

els and their p

First investig

els are describ

nCr steels a

nsmission of p

d a ductile

ting, as shown

Laser beam

havior of w

tallography

asurement. A

ected, as show

d H800 in lap j

ngth Steels

l in combina

physical prop

gations of la

bed in Ref. [7

as a base

power under

fracture beh

n in Fig. 4.

welded she

welded aust

inspection

A softening i

wn in Fig. 5. T

oint condition

tion with tho

perties.

aser beam w

7]. Laser beam

material of

every directio

havior during

eets exhibit

tenitic mate

with a

in the weld s

The often vis

.

179

ose austenitic

welded MnCr

m joints with

ffer a high

on of loading

g destructive

the typical

erials under

a hardness

seam can be

ible behavior

9

c

r

h

h

g

e

l

r

s

e

r

180

of ferritic ca

the heat-affe

with brittle e

materials.

Metallurg

effect is tha

process an

microstructu

H500 base

With the be

combination

zones are no

they are a

explanation

three-point b

The profile w

Fig. 6 Comp

arbon steels w

fected and w

effects, canno

gical backgro

at the weldi

d reverses

ure. As a res

material is r

enefit of a ful

n with a TWIP

ot a weak po

further cras

can be rep

bending test w

was worked o

parison of hard

Laser Bea

with an increa

elded zones,

ot be detected

ound of the

ing works li

locally the

sult the hardn

reached in th

ll austenitic m

P hardening e

oint in a con

sh and safety

presented wi

where a cup p

out as a tailor

dness for a wel

am Welding o

ase of hardnes

often comb

d for the austen

visible soften

ke an annea

e twins in

ness of the F

he welded zo

microstructur

effect, the we

nstruction, in

y potential.

th a high-sp

profile was u

red welded b

lded and then

of Alloyed Ult

ss in

ined

nitic

ning

aling

the

Forta

ones.

re in

lded

fact

The

peed

used.

lank

of a

to a

Fig

com

pro

A

twin

hard

low

The

con

the

cold

wel

safe

com

impact-loaded

ra-High Stren

a Forta H800

a zinc-coated

. 6 shows

mparison of

file.

A hardening

ns restart bu

dening speed

wer number o

erefore the jo

nstruction. Du

hardness of

d-formable

lded as well

ety requirem

mponents of a

d sample.

ngth Steels

with an H10

micro-alloye

a hardness

a non-tested

can be detec

uilding in the

d is much hig

of twins, here

oint areas are

uring a critica

the base mat

austenitic F

as in base m

ents for intru

a car body.

000, and then

ed steel as a l

measuremen

d and an imp

cted after the

e microstruc

gher for the

e the laser w

e not the wea

al impact the

terial again. T

orta H-serie

material condi

usion and cr

n spot-welded

locking plate.

nt with the

pact stressed

impact. The

ture and the

areas with a

welded seam.

ak point in a

e joints reach

Therefore the

es fulfill in

itions highest

rash relevant

d

.

e

d

e

e

a

.

a

h

e

n

t

t

The Forta

material eva

as well as

weldability

Aachen Uni

supports th

documentati

Different gu

dissimilar j

support the

about me

recommenda

4. Hot-For

The Forta

manufacturi

reached a

“press-harde

1,200 MPa

press-harden

ferritic-mart

changed af

martensitic-b

material is

carbon and 1

material adv

tensile stren

extra-ordina

hot-forming

Fig. 7 Mech

a H-series rea

aluation proce

s the confir

according to

versity, ISF W

e complete

ion guideline

uidelines and

joining com

processing i

etallurgical

ations are giv

rming Mat

a H1200PH

ng way and

fter hot-for

ening”, a yie

a and “PH”

ning. This

tensitic micro

fter the ho

based matrix

based on a

13 wt.% chro

vantage is the

ngth (Rm ≈ 1

ary elongati

, as shown in

hanical-technol

Laser Bea

ached success

ess according

rmation of

SEP1220-3

Welding and

process of

for the laser b

d test results

mbinations a

industry. Fur

aspects

ven in Refs. [

erials

represents a

material desi

rming, or

eld strength

” specified

stainless

ostructure in

ot-forming p

x with auste

steel contai

mium 1.4034

e combinatio

,850 MPa) c

ion (A80

n Fig. 7.

logical values o

am Welding o

sfully the gen

g to SEP1245

the laser-b

[9]. The RW

Joining Inst

the testing

beam weldab

s for similar

are available

rther informa

and wel

10, 11].

a complete o

ign. The mate

often ca

level of Rp0

the ability

steel has

initial state

process into

enite parts.

ining 0.45 w

4 (X46Cr13).

on of a very h

ombined with

≈ 13%) a

of different ho

of Alloyed Ult

neral

5 [8]

beam

WTH

itute

and

bility.

and

e to

ation

ding

other

erial

alled

0,2 ≈

for

a

and

o a

The

wt.%

The

high

h an

after

O

com

man

form

sub

400

of

adv

nee

alum

fast

add

stai

in

prop

tem

com

form

stai

she

wha

thic

pres

T

bas

adv

T

exc

ben

t-formed steels

ra-High Stren

Other hot-f

mparison to

nganese-boro

ming starts

sequent quen

0 °C for five

hot-forming

vantages: The

ed a furth

minum-siliciu

t heating proc

ditional diffus

inless steel fu

very homo

perties. Furth

mperature (M

mplex parts

ming operat

inless steels

ets (down to

at permit fu

ck plates up t

ssure tanks.

The building

ed microstru

vantage of the

This effect is r

cellent prope

nding tests wh

s [17].

ngth Steels

forming pr

o establishe

on steel 22M

with auste

nching in the

minutes. Nev

parameters

e chromium a

her scale-re

um (+AS) and

cesses with in

sion time is

unctions as an

ogeneous an

hermore the

Ms) supports

because mo

tion is ava

are industria

0.5 mm) over

urther lightwe

to 6.0 mm ar

of austenite

ucture after

e Forta H1200

responsible fo

erties during

here high ben

rocess para

ed materials

MnB5 are ne

nitization at

mould, and

vertheless thi

results in d

alloyed mater

esistance c

d can be there

duction or co

necessary. M

n air hardener

nd repeatab

low marten

the hot-form

re process t

ailable. The

al available

r a large widt

eight potenti

re possible fo

islands in th

hot-forming

0PH, as show

for the high el

g subsequent

nding angles

181

ameters in

s like the

ecessary: hot

t 1150 °C,

tempering at

is adjustment

different new

rial does not

oating like

efore used for

onduction. No

Moreover the

r what results

ble material

nsitic starting

ming of very

time for the

martensitic

also as thin

th (1,250 mm

ial. But also

or hot-formed

e martensitic

g is a key

wn in Fig. 8.

longation and

t three-point

over 90° can

n

e

t

,

t

t

w

t

e

r

o

e

s

l

g

y

e

c

n

m)

o

d

c

y

d

t

n

182

Fig. 8 Retai

be reached.

by the descr

Former li

martensitic s

as limited

some speci

although the

laser beam w

process poss

weld heat tre

mechanical p

5. LaserHot-Form

Two diffe

suitable to a

component

engineering:

butt joint in

tailored we

afterwards. F

is hot-forme

then welded

of the car bo

weldability

hot-formed s

ined and rever

Further a goo

ribed microstr

iterature desc

stainless steel

[12-14]. The

ial assistanc

e material w

welding whic

sible to be ap

eatment was

properties of

r Beam mable Mater

ferent ways o

apply the For

for transpor

: The first one

initial, cold-r

elded blank

For the secon

ed in a first ste

d as a lap or a

ody. Therefor

of the base m

state.

11

Laser Bea

sion austenite

od crash perf

ructure effect

cribed genera

ls with up to 0

erefore the m

ce in point

was proven to

ch is the only

pplied to this

proven to be

f the welds.

Weldabilrials

of manufactu

rta H1200PH

rt application

e uses laser b

rolled materia

which can

nd possibility

ep to create th

butt joint to o

re it is import

material in ini

50 °C/5 min/WQ

am Welding o

after hot-form

formance is g

ts.

al weldability

0.46 wt.% car

material requ

of weldab

o be suitable

y fusion wel

class of steel

e beneficial to

lity of

uring seem to

as a hot-for

ns and car b

eam welding

al state to crea

be hot-for

the base mat

he component

other compon

tant to ensure

itial as well a

1150 °C/5

of Alloyed Ult

ming and annea

given

y of

rbon

uires

bility

e for

ding

ls. A

o the

the

o be

rmed

body

as a

ate a

rmed

erial

t and

nents

e the

as in

S

mar

crac

hea

mar

star

inte

foll

diss

Fur

mat

tem

T

AiF

“Inv

chro

usin

(IG

of h

as w

wel

T

seam

trea

hard

lase

min/WQ + 400 °C/1

ra-High Stren

aling of FortaH

Short thermal

rtensitic stain

cks and high

at-control is

rtensitic micr

rting tempe

ercooling to

lowing temp

solution of th

rther referenc

terials and the

mperature can

The following

F-funded r

vestigations

omium steels

ng laser beam

GF project num

heat input and

well as disc l

lding paramet

The results of

m and the he

atments of the

dness of in

er welded is s

1150 °C1 min/WQ

ngth Steels

H1200PH.

cycles should

nless steels in

hardness gra

desirable. T

rostructure, a

erature (Ms

150 °C-200

ering below

e alloy carbid

ces to the w

e calculation

be given wit

g investigatio

research pr

on fusion w

s with a mart

m and gas-met

mber 17.433N

d seam geom

laser were us

ters are prese

f hardness mea

eat affected zo

e H1200PH ar

nitial cold-ro

shown with b

C/5 min/WQ + 400 °C

d be preferred

general. But

adients, a mat

To relax th

pre-heating t

) combined

°C after we

the temper

des is appropr

welding behav

of the marten

th Refs. [17-1

ns were work

roject FOS

welding of h

tensitic micro

tal-arc-weldin

N). To test di

metry, carbon

sed as beam

ented in Table

asurement ac

ones for diffe

re displayed i

olled sheets

lack graphs (

C/30 min/WQ

d for welding

to avoid cold

erial-suitable

he tetragonal

to martensitic

d with an

elding and a

rature of the

riate [15, 16].

vior of those

nsitic starting

19].

ked out in the

STA P905

high-strength

ostructure by

ng processes”

ifferent ways

dioxide laser

sources. The

e 2.

ross the weld

erent thermal

in Fig. 9. The

which are

(rhombs) and

g

d

e

l

c

n

a

e

.

e

g

e

5

h

y

”

s

r

e

d

l

e

e

Table 2 App

Fig. 9 Hard

clarifies an

gradient is

literature an

blue graphs

plied welding p

dness curves of

increase to

well-known

nd results in a

(squares) illu

Laser Bea

parameters for

f Forta H1200P

600 HV0.3

n in the m

a cold crack b

ustrate the har

am Welding o

r laser beam w

PH for differen

3. This hard

mentioned be

behavior. But

rdness of weld

of Alloyed Ult

welding of H120

nt thermal trea

dness

efore

t the

ds in

pres

the

The

pre-

ra-High Stren

00PH.

atment conditio

ss-hardened c

heat-affected

e dashed line

-heating, soli

ngth Steels

ons.

condition. Wi

d zone by 80

s represent to

id lines to p

ithout pre-hea

to 110 points

o welds produ

pre-heated we

183

ating a dip in

s is observed.

uced without

elds (TMs =

3

n

.

t

=

184

300 °C).

press-harden

positive infl

zones to th

hot-formed c

The fatigu

test the lifet

was analyz

amplitudes.

pulsator, wh

Fig. 10 Cho

Especially

ned conditio

uence and gr

e level of th

condition.

ue behavior is

time conditio

zed with a

The test were

hich enables a

sen sample geo

Laser Bea

for the

n, the pre-h

rades the hard

he base mate

s an importan

ons of welde

cyclic test

e carried out u

a test frequen

ometry (above

am Welding o

laser-welds

heating show

dness in the w

erial hardnes

nt investigatio

ed structures

under cons

using a resona

ncy of about

e) and resulting

of Alloyed Ult

in

ws a

weld

ss in

on to

and

stant

ance

100

Hz

rati

cho

test

sam

1·10

SEP

join

righ

hea

g fatigue behav

ra-High Stren

depending o

o RF = 0. A

osen as failure

t frequency dr

mples without

07 cycles. T

P1240 [20] h

nt vertical to

ht side. Fig. 1

at-control.

vior (below).

ngth Steels

n the specim

A crack leng

e criterion an

rop off by 1 H

t rupture, the

The specimen

as been chos

the cyclic l

10 also repre

men’s stiffnes

gth of about 0

nd could be d

Hz. In the ca

e test was sto

n geometry

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Laser Beam Welding of Alloyed Ultra-High Strength Steels

185

As a result of this project extensive guidelines about

how to weld and how to treat the ultra-high strength

grade were created. The presentations at the

project-closing colloquium [21-23] enlarge significant

the knowledge of the former literature and add new

manufacturing possibilities for the processing industry.

6. Conclusions

Outokumpu’s new Forta H-series combine

ultra-high strength alloyed materials with different

microstructures and hardening effects for different

manufacturing processes like cold- or hot-forming. The

weldability depends on the microstructure and alloying

elements of the respective chosen material. But

independent, the process of laser beam welding with its

specific advantages occupies a key role by ensuring the

weldability of the materials or different material

conditions. Therefore laser welding enables the

production of lightweight and crash-safety components

with new ultra-high strength materials for future car

bodies and transport applications.

Acknowledgments

Special thanks are given to all research institutes,

especially to professor Dr. Uwe Reisgen (RWTH

Aachen University ISF Welding and Joining Institute),

Dr. Rainer Wagener (Fraunhofer LBF Darmstadt) and

Vitalij Janzen (LWF Paderborn).

References

[1] Schramm, D., and Koppers, M. 2014. Das Automobil im Jahr 2025—Vielfalt der Antriebstechnik. Springer-Vieweg.

[2] Asnafi, N. 2015. “Sustainable Product and Production Development.” Innovation Workshop Stainless Steel, Olofstöm.

[3] Meschut, G. 2003. Zukünftige Fügekonzepte für Automobilstrukturen in Mischbauweise, Dresdner Leichtbausymposium.

[4] Ratte, E. 2007. Wasserstoffinduzierte verzögerte Rissbildung austenitischer Stähle auf CrNi(Mn)- und Mn-Basis, dissertation IEHK RWTH Aachen, Shaker Verlag, Band.

[5] Dilthey, U. 2005. Schweißtechnische Fertigungsverfahren

– Verhalten der Werkstoffe beim Schweißen, 3rd ed.

Springer Vieweg.

[6] Bracke, L., de Cooman, B., Liebeherr, M., and Akdur, N.

2005. “Phase Transformations in High Strength Austenitic

FeMnCr Steels.” Solid-Solid Phase Transformations in

In-organic Materials 1: 905-10.

[7] Mujica, L., Weber, S., Thomy, C., and Vollertsen, F. 2009.

“Microstructure and Mechanical Properties of

Laser Welded Austenitic High Manganese Steels.”

Science and Technology of Welding and Joining 14 (6):

517-22.

[8] SEP1245. Material Approval Process for Automotive

Sheet Steel (Cold Forming), 1st ed. 11/2011.

[9] SEP1220-3. Testing and Documentation Guideline for the

Joinability of Thin Sheet of Steel, Part 3: Laser Beam

Welding, edition: 18.02.2009.

[10] Lindner, S. 2014. “Joining Processing Advices of New

Manganese-Chromium Steels with High Strength and

without Nickel for Automotive-Typical Joining

Combinations.” 4th International Conference on Steels in

Cars and Trucks, Braunschweig.

[11] Lindner, S. 2014. “Welding New Manganese-Chromium

Steels with High Strength for Railway Vehicle

Applications.” 3rd International Conference

JOIN-TRANS, SLV Halle.

[12] Folkhard, E. 1984. Metallurgie der Schweißung

nichtrostender Stähle. Wien, New York: Springer-Verlag.

[13] Nichtrostende Stähle, Krupp Stahl AG, 1981.

[14] Strassburg, F. W., and Wehner, H. 2009. Schweißen

nichtrostender Stähle, 4th ed. DVS Media.

[15] Schulze, G. 2010. Metallurgie des Schweißens. Berlin

Heidelberg: Springer Verlag.

[16] Bleck, W. 2007. “Material Science of Steel.” Department

of Ferrous Metallurgy, RWTH Aachen University.

[17] Brümmer, A. 2010. “Investigation of the Corrosion Properties of Hot-Stamped Stainless Steels after Resistance-Spot-Welding.” Master thesis at RWTH Aachen.

[18] Dahmen, M., Daamen, M., Janzen, V., Lindner, S., Schneider, A., and Wagener, R. 2014. “Laser Beam Welding of New Ultra-High Strength and Supra-Ductile Steels.” 4th International Conference on Steels in Cars and Trucks, Braunschweig.

[19] Dahmen, M., Janzen, V., Lindner, S., and Wagener, R. 2015. “Mechanical Properties of Laser Beam Welded Ultra-High Strength Chromium Steel with Martensitic Microstructure.c 15th Nordic Laser Materials Processing Conference, Lappeenranta.

[20] SEP1240. Testing and Documentation Guideline for the Experimental Determination of Mechanical Properties of

Laser Beam Welding of Alloyed Ultra-High Strength Steels

186

Steel Sheets for CAE-Calculations, 1st ed. 07/2006. [21] Dahmen, M. 2014. “Schweißeignung Nichtrostender

Chromstähle mit Martensitischem Gefüge.” Colloquium of the Project SECOMAL, Aachen.

[22] Janzen, V. 2014. “Crashverhalten Lasergeschweißter, pressgehärteter martensitischer Chromstähle im

Zusammenbau von Komponenten.c.” Colloquium of the Project SECOMAL, Aachen.

[23] Wagener, R. 2014. “Schwingfestigkeit gleich- und ungleichartiger Verbindungen von martensitischen Chromstählen für die Anwendung in Tailored Blanks.” Colloquium of the Project SECOMAL, Aachen.