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Procedia
Procedia CIRP
CIRP 00
00 (2018)
(2018) 000–000
000–000
ScienceDirect
ScienceDirect www.elsevier.com/locate/procedia
www.elsevier.com/locate/procedia

Procedia CIRP 00 (2017)

Procedia 000–000
CIRP 74 (2018) 748–751
www.elsevier.com/locate/procedia

th
th
10
10
10thCIRP
CIRP
CIRPConference
Conference
Conferenceon
on
onPhotonic
Photonic
PhotonicTechnologies
Technologies
Technologies[LANE
[LANE
[LANE2018]
2018]
2018]

Influence of heat28th
input
CIRPand preheating
Design Conference, on
Maythe cooling
2018, rate, microstructure
Nantes, France
and mechanical properties at the hybrid laser-arc welding of API 5L X80
A new methodology to analyze thesteel functional and physical architecture of
existing products
aa
for ana,b,*
assembly oriented
a,b,* aa
product
cc
familyddidentification
dd
G.
G. Turichin
Turichin ,, M.M. Kuznetsov
Kuznetsov ,, A. A. Pozdnyakov
Pozdnyakov ,, S. S. Gook
Gook ,, A. A. Gumenyuk
Gumenyuk ,, M. M. Rethmeier
Rethmeier
aa Paul
Saint-Petersburg
Stief
Saint-Petersburg State
*,
State Marine
Jean-Yves
Marine Technical
Dantan,
Technical University,
Alain
University, Lotsmanskaya
Lotsmanskaya str.
str. 3,
Etienne,
3, Saint
Ali
Saint Petersburg,
Siadat
Petersburg, 190121,
190121, Russian
Russian Federation
Federation
bb
Peter
Peter
École the
the Great
Great
Nationale Saint-Petersburg
Saint-Petersburg
Supérieure d’Arts etPolytechnic
Polytechnic
Métiers, Arts University,
University, Polytechnicheskaya
et MétiersPolytechnicheskaya
ParisTech, LCFC EA str.
str.4495,
29,
29, Saint
Saint Petersburg,
Petersburg,
4 Rue Augustin 195251,
195251, Russian
Fresnel, Russian
Metz Federation
Federation
57078, France
cFraunhofer Institute
cFraunhofer Institute for
for Production
Production Systems
Systems and
and Design
Design Technology
Technology IPK,
IPK, Berlin,
Berlin, Germany
Germany
dFederal Institute
dFederal Institute for
for Materials
Materials Research
Research and
and Testing
Testing BAM,
BAM, Berlin,
Berlin, Germany
Germany
* Corresponding author. Tel.: +33 3 87 37 54 30; E-mail address: paul.stief@ensam.eu
** Corresponding
Corresponding author.
author. Tel.:+7-812-552-9843
Tel.:+7-812-552-9843 ;; fax:
fax: +7-812-552-9843. E-mail address:
+7-812-552-9843. E-mail address: kuznetsov_mich@ltc.ru
kuznetsov_mich@ltc.ru

Abstract
Abstract
Abstract
In today’s business environment, the trend towards more product variety and customization is unbroken. Due to this development, the need of
agile and reconfigurable production systems emerged to cope with various products and product families. To design and optimize production
This
This study
study investigates
investigates the the influence
influence of of hybrid
hybrid laser-arc
laser-arc welding
welding parameters:
parameters: heat heat input
input and
and preheating
preheating on on the
the cooling
cooling rates,
rates, microstructure
microstructure and and
systems
mechanical properties
mechanical
as well as to choose
properties of of the
the optimal
the welding
welding joint.
product
joint. Samples
matches,
Samples from from API
product
API 5L5L X80
analysis
X80 steel
methods
steel with
with root
are needed. 14
root thickness
thickness 14
Indeed,
mm were
mm
mostwelded
of the using
were welded
known methodswire
using welding
welding wire
aimMF
MF
to
analyze
940 M.
940
a product
M. Decreasing
or one
Decreasing cooling
product
cooling rate
family
rate of
on
of welds
the
welds from
physical
from 588
level.
588 °C/sec
°C/sec up
Different
up to
to 152
product
152 °C/sec,
families,
°C/sec, weld
weld metal
however,
metal hardness
may differ
hardness from
largely
from 343±12
343±12 HV
in terms
HV up
of
up to
the
to 276±6
number
276±6 HVHV and
and
and
nature of tensile
ultimate
ultimate components.
tensile strength
strength This
from
fromfact1019.5±14
impedes an
1019.5±14 MPa
MPaefficientto comparison
up to
up 828±10 MPa
828±10 MPaand andchoice
and of appropriate
increasing
increasing product
bainite phase
bainite phase termfamily
term thecombinations
of the
of weld metal
weld metal wasfor detected
was the production
detected at the
at the
system. A new
increasing
increasing methodology
preheating
preheating is proposed
temperature
temperature up to
up to to analyze
180
180 °C and
°C andexisting
maximal
maximal products in view
heat input.
heat input. Theofmathematical
The their functional
mathematical and physical
relations
relations of the
of architecture.
the input
input The parameters
and output
and output aim is to cluster
parameters were
were
these products
created
created in newregression
using linear
using linear assembly oriented
regression equations.
equations. product families
Preheating
Preheating for the optimization
temperature
temperature 180 °C
180 °C allowsof existing
allows assembly
increasing
increasing maximal
maximal lines and thespeed
welding
welding creation
speed of
up to
up future
to more reconfigurable
more than
than 3.0 m/min
3.0 m/min
assembly systems.
with acceptable
with Based
acceptable welding on
welding joint Datum
joint quality.
quality.Flow Chain, the physical structure of the products is analyzed. Functional subassemblies are identified, and
a©©functional analysis
Authors.isPublished
performed. Moreover, a hybrid functional and article
physical architecture graph (HyFPAG) licenseis the output which depicts the
2018
© 2018
similarity
The
2018 The
The Authors.
Authors.
between
Published
Published
product
by Elsevier
by
by
families
Elsevier Ltd.
Elsevier
by
Ltd.
Ltd.
providing
This is
This
This is an
is
design
an open
an open access
open
support
access
access
to
article under
article
both,
under
under
production
the CC
the
the CC BY-NC-ND
CC
system
BY-NC-ND
BY-NC-ND
planners
license
license
and product designers. An illustrative
(http://creativecommons.org/licenses/by-nc-nd/3.0/)
(http://creativecommons.org/licenses/by-nc-nd/3.0/)
(https://creativecommons.org/licenses/by-nc-nd/4.0/)
example of a under
Peer-review
Peer-review nail-clipper
under is used to
responsibility
responsibility of
of explain
the
the the proposed
Bayerisches
Bayerisches methodology.
Laserzentrum
Laserzentrum GmbH.
GmbH. An industrial case study on two product families of steering columns of
Peer-review under responsibility of the Bayerisches Laserzentrum GmbH.
thyssenkrupp Presta France is then carried out to give a first industrial evaluation of the proposed approach.
© 2017 The
Keywords:
Keywords: Authors.
Hybrid
Hybrid Published
laser-arc
laser-arc welding;
welding;byAPIElsevier
API 5L X80B.V.
5L X80 steel;
steel; cooling
cooling rate;
rate; microstructure;
microstructure; mechanical
mechanical properties;
properties; regression
regression equations
equations
Peer-review under responsibility of the scientific committee of the 28th CIRP Design Conference 2018.

Assembly; Design method; Family identification

1.Keywords:
1. Introduction
Introduction cooling
cooling raterate narrows
narrows HAZ HAZ of of the
the weld
weld at at the
the HLAW
HLAW X120 X120
steel
steel [7].
[7].
Cooling
Cooling rate,
rate, microstructure
microstructure and and mechanical
mechanical propertiesproperties of of So
So many
many publications
publications testify testify about
about influence
influence ofof the
the heat
heat
the
the welds
welds can
can
1. Introduction be
be changed
changed in
in the
the wide
wide range
range at
at the
the hybrid
hybrid laser-
laser- input
input and
and preheating
preheating on
on the
the microstructure
microstructure
of the product range and characteristics manufactured and/or and
and mechanical
mechanical
arc
arc welding
welding (HLAW) (HLAW) using using heat heat input
input and and preheating
preheating properties
properties
assembledof of
in the
the welds
this welds
system. at
atIn
the
the HLAW.
HLAW.
this context,But
But
thesome
some
main publications
publications
challenge in
temperature.
temperature. So,
So, welding
welding speed
speed
Due to the fast development in the domain of increases
increases on
on the
the 14%
14% and
and weld
weld testify
testify about
about absence
absence of
of the
the influence
influence [8].
[8].
modelling and analysis is now not only to cope with single
metal
metal hardness
hardness decreases
decreases on
on the the 17%17% The
The publication
publication is is devoted
devoted research
research of of the
the heat
heat input
input and
and
communication and an ongoing trend(from
(from 410HV
410HV up
of digitization up and to
to products, a limited product range or existing product families,
350HV)
350HV) at
at the
the HLAW
HLAW samples
samples from
from Х70
Х70 and
and S690QL
S690QL steels
steels preheating
preheating temperature
temperature influence influence on on thethe cooling
cooling rate,
rate,
digitalization, manufacturing enterprises are facing important but also to be able to analyze and to compare products to define
with
with constant
constantin laser
laser power
power using
usingenvironments:
preheating
preheating [1,2]. [1,2]. Similar
Similar microstructure,
microstructure, hardness,
hardness, ultimate
ultimate tensile
tensile strength
strength and
and impact
impact
challenges today’s market a continuing new product families. It can be observed that classical existing
results
results were
were received
received at
at the
the HLAW
HLAW X65
X65 steel
steel [3].
[3]. Impact
Impact energy
energy of of the
the welds
welds at at the
the HLAW
HLAW samples
samples fromfrom X80
X80 steel
steel and
and
tendency towards reduction of product development times and product families are regrouped in function of clients or features.
toughness
toughness of
of the
the weld
weld increases
increases at
at the
the increasing
increasing heat
heat input
input up
up itit continues
continues of of the
the last
last publication
publication [9].[9]. Regression
Regression equations
equations
shortened product lifecycles. In addition, there is an increasing However, assembly oriented product families are hardly to find.
to
todemand
defined
definedoflevel,
level, exceeding
exceeding of of the
the heat
heat input
input level
level has
has describing
describing influence
influence of of thethe welding
welding speedspeed andand preheating
preheating
customization, being at the same time inopposite
opposite
a global On the product family level, products differ mainly in two
influence
influence on
on the
the mechanical
mechanical properties
properties [4].
[4]. The
The ratio
ratio of
of laser
laser temperature
temperature on on thethe weld
weld metal
metal hardness
hardness and and ultimate
ultimate tensile
tensile
competition with competitors all over the world. This trend, main characteristics: (i) the number of components and (ii) the
and
and arc
arc power
power influences
influences on
on the
the mechanical
mechanical properties
properties and
and strength
strength were
were created
created in in the
the work
work using
using experimental
experimental results.
results.
which is inducing the development from macro to micro type of components (e.g. mechanical, electrical, electronical).
degree
degree
markets, of
of deformation
deformation
results in diminished of
of the
the weld
weldlot[5].
[5]. Cooling
sizesCooling
due rate rateaugmenting
to decreases
decreases Classical methodologies considering mainly single products
at
atproduct
the
the presence
presence
varieties and
and(high-volume
increasing
increasing of oftothe
the arc
arc power
power production)
low-volume [6].
[6]. Increasing
Increasing [1]. or solitary, already existing product families analyze the
To cope with this augmenting variety as well as to be able to product structure on a physical level (components level) which
2212-8271 © © 2018
2018 The Theoptimization
Authors.
Authors. Published
Published by
by Elsevier
Elsevier
2212-8271
identify possible potentials in Ltd.
Ltd.
the This
This is
is an
existing an open
opencauses
access
access article
article under
under the
difficulties theregarding
CC
CC BY-NC-ND
BY-NC-ND license
license
an efficient definition and
(http://creativecommons.org/licenses/by-nc-nd/3.0/)
(http://creativecommons.org/licenses/by-nc-nd/3.0/)
production
Peer-review system,
Peer-review under it is
under responsibility important
responsibility of of the to have
the Bayerisches a precise
Bayerisches Laserzentrum knowledge
Laserzentrum GmbH. GmbH. comparison of different product families. Addressing this
2212-8271 © 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(https://creativecommons.org/licenses/by-nc-nd/4.0/)
2212-8271 © 2017 The Authors. Published by Elsevier B.V.
Peer-review
Peer-review under
under responsibility
responsibility of scientific
of the the Bayerisches Laserzentrum
committee GmbH.
of the 28th CIRP Design Conference 2018.
10.1016/j.procir.2018.08.018
 G. Turichin et al. / Procedia CIRP 74 (2018) 748–751 749
2 Author name / Procedia CIRP 00 (2018) 000–000

2. Experimental procedure Three test samples for Charpy impact test, two for ultimate
tensile strength and one for hardness test were made from
2.1. Welding equipment and test materials every weld.
a b
Experimental part was carried out using a 20 kW fiber laser
YLR – 20000 (IPG) and semiautomatic welding machine
Qineo Pulse 600А (Cloos). Preheating of the test samples was
performed using current source GLW 450 I-H-P-R (Cloos)
with electric heating element.
Welding samples from API 5L X80 steel with overall
dimensions 240x100x23.7 mm3, root face thickness 14 mm Fig. 1. Scheme of (a) ultimate tensile strength sample with boundary
dimensions and (b) ultimate tensile strength samples location in weld metal
and groove angle 22.5° were welded using metal cored welding
wire MF 940 M (EN ISO 18276) with diameter 1.2 mm.
Chemical compositions of the steel and welding wire are given All tests results were controlled in accordance with DIN
in Table 1 and Table 2 accordingly. EN ISO 3183-2011 «Petroleum and Natural Gas Industries -
Steel Pipe for Pipeline Transportation Systems».
Table 1. Chemical compositions of the API 5L X80 steel (wt %)
C Si Mn P S Cr Ni
2.3. Design of the experimental work
0.052 0.33 1.82 0.008 0.0008 0.17 0.01
Mo Cu V Nb Ti N Fe The study was carried out using DOE 2k type. The
0.14 0.02 0.004 0.04 0.012 0.004 Bal. mathematical relations of the input and output parameters were
created using linear regression equations. Input parameters are
Table 2. Chemical compositions of the welding wire MF 940 M (wt %)
welding speed (S) and preheating temperature (T). Output
C Si Mn P S Ni N Fe parameters are average weld metal hardness (HV), average
0.05 0.6 1.4 0.015 0.015 2.0 0.004 Bal. weld metal ultimate tensile strength (G).
Heat input depends from welding speed and laser power.
HLAW was carried out in the PC welding position. Arc Welding speed diapason was chosen from 1.8 m/min up to 3
torch had angle of 30° from laser beam with wire stick out 16 m/min. Laser power (PL) and wire rate (R) values depended
mm. Laser head and arc torch were mounted on an industrial from welding speed for creating welds with stable through
robot. Arc had a leading position. Distance from the axes of penetrations.
the electrode to the laser beam was 3.5 mm. Laser beam focal Preheating temperature was varied from 20 °C (room
plane was below the top surface on 4 mm. Gas mixture M21 temperature) up to 180 °C. Upper limit of the preheating
(82% Ar and 18% CO2) with supply rate of 20 l/min was used. temperature was chosen for avoiding unnecessary changes in
the structure of the base material.
2.2. Testing equipment and welds inspections
3. Experimental results
Defects classification was carried out according to DIN EN
ISO 13919-1. Measuring of thermo cycle of the HLAW was The HLAW parameters are shown in the Table 3.
performed using four alumel-chromel thermocouples which
were soldered on the back side of the welded joint by a Table 3. HLAW parameters
resistance welding machine PSG 1000/3 with starting point of Weld, T, S, PL, R, IA, UA, Q,
1-1.5 mm from the joint edge and 30 mm interval. No 0
C m/min kW m/min A V kW*min/m
Examination of the welds microstructure was performed 1 180 3.0 18.3 18 491 34.7 11.8
using optical microscope Polyvar Met with 500x magnification 2 180 1.8 15.6 11 334 30.6 14.3
3 20 3.0 18.3 18 507 36.2 12.2
in three points on vertical axis of the weld metal: 2 mm from 4 20 1.8 15.6 11 327 30.4 14.2
the root, at the middle and 2 mm from the top. 5 100 2.4 18 14.5 420 32.6 13.2
Hardness tests were performed across the weld metal, 6 100 2.4 18 14.5 420 32.6 13.2
fusion zone, HAZ and the base metal according to DIN EN 7 100 2.4 18 14.5 420 32.6 13.2
ISO 14577 at room temperature in three lines: 2 mm from the
root, at the middle and 2 mm from the top of the weld. 3.1. Welds appearance
Charpy impact tests were carried out according to DIN EN
10045 at temperature -20 °C with V-notch located at the middle All welds (except weld 5) had a stable full penetration.
of weld metal. Weld 5 had instability full penetration partly. Minor undercuts
Weld 3 with the highest cooling rate of the weld metal was were observed in the weld 2 and weld 3.
chosen for ultimate tensile strength testing. Test samples were
made using electric discharge sawing with boundary 3.2. X-ray inspection
dimensions in 2 times less than minimal boundary dimensions
from DIN 50125-2009. Scheme of ultimate tensile strength Insignificant number of the pores were detected in the
sample and the samples location in weld metal are shown on metal of the welds 6 and 7. Other welds didn’t have inner
Fig. 1. Testing of the samples was carried out according to defects and had high quality accordingly standard EN ISO
DIN EN ISO 6892-1:2009 using Material Test System 810 13919-1. All welds metal zones with inner defects were cut
machine. and were not researched.
750 G. Turichin et al. / Procedia CIRP 74 (2018) 748–751
Author name / Procedia CIRP 00 (2018) 000–000 3

3.3. Thermal cycle of the HLAW element Mn (Table 1) also. The alloying elements suppressed
carbon diffusion at the polymorphic transformation because of
The thermo cycles of the HLAW for different welding decrease of the point Ac3. Therefore weld metal with
parameters are presented on the Fig. 2. martensite and bainite phase was formed because of high
cooling rate. Proportion of the martensite and bainite of the
weld metal was depend from cooling rate. Weld metal had
more martensite at the cooling rate increasing and opposite
phase composition at the cooling rate decreasing (regime 3 -
51.7% martensite and 48.3% bainite; regime 4 - 43.3%
martensite and 56.7% bainite).
Martensite phase increased in the upper part of the weld
metal because of irregular mixing welding wire alloying
elements (Ni and Mn) in the welds and their higher
concentration in the upper part of the weld metal [10,11].

3.5. Hardness test and ultimate tensile strength results

Average hardness of the all welds are shown in Table 5.

Fig. 2. Thermo cycles of the HLAW in HAZ
Test samples from the weld 3 were broke at the base
material with average ultimate tensile strength 678 MPa.
Heat input decreased from 14.3 kW*min/m (regime 2 –
Average values of the all tests are shown in the Table 6.
yellow curve) up to 11.8 kW*min/m (regime 1 – red curve) at
the welding speed increasing from 1.8 m/min up to 3.0 m/min, Table 6. Values average hardness and ultimate tensile strength of the weld
Fig. 2. Take away heat from weld metal in the base metal metal with standard deviation
direction is more intensively in the initial moment because of Welds 1 2 3 4 5 6 7
high temperature gradient. The base metal temperature Av. value
increased during the weld metal cooling. Therefore hardness, 299±2 276±6 343±12 305±16 311±6 327±16 320±15
HV
temperature gradient of the HAZ (at the measuring temperature σav, МPa 852.5±26 828±10 1019.5±14 959±0 949.8±16
diapason from 800-500 °C) with high heat input had less value
by comparison temperature gradient at the HLAW with low Weld metal strength properties increased at the cooling rate
heat input (red curve (regime 1) – 180 °C/sec and yellow curve increasing (regime 3) and it can be seen opposite trend at the
(regime 2) – 152 °C/sec). The temperature gradient and cooling decreasing cooling rate because of welding speed decreasing
rate decreases at the increasing preheating temperature (red (regime 4) or preheating temperature increasing (regime 1),
curve (regime 1) – 180 °C/sec and pink curve (regime 3) – 588 Table 6.
°
C/sec), Table 4. Carbon atoms didn’t diffuse from crystallization and distort
Table 4. Cooling curves parameters at HLAW
crystal lattice because of high cooling rate of the welds metal
at the HLAW. Therefore hardening structure of the metal with
Cooling curve
parameters / Welds
1 2 3 4 5 unsatisfying welds mechanical properties can be obtained [12].
Cooling time (T5/8), sec 1.67 1.98 0.51 0.84 0.91 So weld metal (regime 3 – cooling rate 588 °С/sec) had
Cooling rate, °C/sec 180 152 588 357 330 average hardness 343HV. It is higher than 325HV accordingly
to the standard DIN EN ISO 3183-2011 «Petroleum and
3.4. Metallographic examination Natural Gas Industries - Steel Pipe for Pipeline Transportation
Systems». Average weld metal hardness was decreased down
Few incomplete fusions and intergranular liquations were to 299HV because of preheating temperature of 180 °С using.
found at the top and at the root of the weld 1 accordingly. In other words welds with satisfying mechanical properties can
Microstructure of the welds metal consisted from be obtained at the welding speed more than 3.0 m/min using
martensite and bainite phase components in different preheating temperature of 180 °С and HLAW productivity with
proportions, Table 5. preheating can be increased more than on the 60%.

Table 5. Phase components of the welds metal, % 3.1. Charpy test

Weld, 2 mm from the
2 mm from the top Middle
No top All test samples were broken differently: at the weld metal
1 80m.+20b. 25m.+75b. 10m.+90b. (3 samples), at the partly base metal and weld metal (12
2 50m.+50b. 25m.+75b. 5m.+95b.
3 100m. 40m.+60b. 15m.+85b.
samples) and at the base metal (5 samples). Impact energy had
4 85m.+15b. 40m.+60b. 5m.+95b. different values because of test samples had different character
5 75m.+25b. 30m.+70b. 10m.+90b. of a fracture, Table 7. Test samples appearance is shown on the
6 75m.+25b. 30m.+70b. 15m.+85b. Fig. 3.
7 75m.+25b. 40m.+60b. 10m.+90b.
m. – martensite; b. – bainite
Table 7. Averaged charpy test results with standard deviation
Welds 1 2 3 4 5, 6, 7
The welding wire MF 940 M has alloying elements Mn and
Impact
Ni in the significant value, Table 2. Base metal has alloying energy, J
176±84.3 145±93.5 247±54.1 259±104 247±100
 G. Turichin et al. / Procedia CIRP 74 (2018) 748–751 751
4 Author name / Procedia CIRP 00 (2018) 000–000

a b c of martensite in the weld metal, hardness and ultimate

tensile strength. Decrease of the heat input and increase
preheating temperature has opposite effect.

• Weld metal has softer microstructure in the root than in the

top because of higher concentration of the Ni and Mn alloy
elements from welding electrode was in the top weld metal
[11].
Fig. 3. Appearance of the character samples fracture: (a) plastic character, 293J
(test sample 1.1); (b) elastic-plastic character, 189J (test sample 3.2); elastic • HLAW of X80 steel with preheating temperature 180 0C
character, 63J (test sample 5.2) increases productivity of the welding more than on the 60%.

Charpy test results didn’t show any correlation between • Regression equations were created for prediction weld
input and output parameters. But it can be noted that test metal hardness and ultimate tensile strength for HLAW pipe
samples were broke at the weld metal with elastic character of steel X80-X120 with welding wire MF 940M or others
the fracture had average value of impact energy 75±24 J. Test wires with similar chemical composition.
samples were broke partly at the weld metal-base metal had
plastic-elastic character of the fracture with average value of Reference
impact energy 226±82 J. And test samples were broke at the
base metal had plastic character of the fracture with average [1] Lahdo, R., Seffer, O., Springer, A., Kaierle, S., Overmeyer, L., Collmann,
value of impact energy 274±84 J. That speaks for higher M., Schaumann, P., Neumeyer, J., Schuelbe, H., Nacke, B., Induction
strength properties of the weld metal and it confirms results of Assisted GMA-Laser Hybrid Welding of High-Strength Fine-grain
the hardness and ultimate tensile strength tests indirectly. Structural Steels. In: Proccedings of the ICALEO Conference, Miami,
Deviation of the path fracture from weld metal to base USA, 2013, paper #902.
metal was described at the laser welding and calling “fracture [2] Lahdo, R., Seffer, O., Springer, A., Kaierle, S., Overmeyer, L., GMA-laser
hybrid welding of high-strength fine-grain structural steel with an inductive
path deviation” (FPD) [13]. The authors list some reasons of
preheating. Physics Procedia 2014; 56: 637–645.
the FPD formation: narrowness of the laser weld metal and [3] Gumenyuk, A., Rethmeier, M., Developments in hybrid laser-arc welding
small volume of the weld metal involved in deformation technology. Handbook of Laser Welding Technologies 2013. p. 505- 521
process, asymmetry of the stress concentrator because of [4] R.S. Funderbur. A look at Heat Input. Welding Innovation 1999; XVI, 1: 1-
specific weld metal form and presence zones of the welds with 4.
softer metal. [5] Maa N., Lib L., Huanga H., Changb Sh., Murakawa H.. Residual Stresses
All charpy test results satisfy of standard DIN EN ISO in Laser-Arc Hybrid Welded Butt-joint with Different Energy Ratios.
Journal of Materials Processing Technology 2015; 220: 36-45.
3183-2011. [6] Moore P.L., Howse D.S., Wallach E.R. Development of Nd:YAG Laser
and Laser MAG Hybrid Welding for Land Pipeline Application. Welding
4. Regression equations and Cutting 2004; 4: 186 – 190.
[7] Wang, H.H., Wu, K.M., Lei, X.W., Qian. Y., Effect of fast cooling process
Regression equations were created using experimental on microstructure and toughness of heat affected zone in high strength
pipeline steel X120. Science and Technology of Welding and Joining
results for the average value of the weld metal hardness and
2012; 17; 4: 309 – 313.
ultimate tensile strength: [8] Cooper, R., Silva, J.H.F., Trevisan, R.E., Influence of preheating on API
5L-X*) pipeline joint welding with selfshielding flux-cored wire. Welding
𝑯𝑯𝑯𝑯𝑯𝑯𝑯𝑯(𝑺𝑺𝑺𝑺, 𝑻𝑻𝑻𝑻) = 𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐, 𝟓𝟓𝟓𝟓𝟓𝟓𝟓𝟓 + 𝟑𝟑𝟑𝟑𝟓𝟓𝟓𝟓, 𝟐𝟐𝟐𝟐𝟓𝟓𝟓𝟓𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐– 𝟐𝟐𝟐𝟐, 𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟎𝟎𝟎𝟎𝟐𝟐𝟐𝟐𝟎𝟎𝟎𝟎– 𝟐𝟐𝟐𝟐, 𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟎𝟎𝟎𝟎 (1) International 2005; 19: 882 – 887.
[9] Turichin G., Kuznetsov M., Sokolov M., Salminen A. Hybrid Laser Arc
Welding of X80 Steel: Influence of Welding Speed and Preheating on the
𝛔𝛔𝛔𝛔в(𝟐𝟐𝟐𝟐, 𝟎𝟎𝟎𝟎) = 𝟖𝟖𝟖𝟖𝟖𝟖𝟖𝟖𝟖𝟖𝟖𝟖, 𝟖𝟖𝟖𝟖𝟖𝟖𝟖𝟖 + 𝟓𝟓𝟓𝟓𝟐𝟐𝟐𝟐, 𝟏𝟏𝟏𝟏𝟖𝟖𝟖𝟖𝟖𝟖𝟖𝟖𝟖𝟖𝟖𝟖– 𝟐𝟐𝟐𝟐, 𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐– 𝟐𝟐𝟐𝟐, 𝟏𝟏𝟏𝟏𝟓𝟓𝟓𝟓𝟓𝟓𝟓𝟓𝟓𝟓𝟓𝟓𝟓𝟓𝟓𝟓𝟓𝟓𝟓𝟓 (2)
Microstructure and Mechanical Properties. Physics Procedia 2015; 78: 35 –
44.
Results of calculations using the equations matches with [10] Gook S., Gumenyuk A., Rethmeier M.. Hybrid laser arc welding of X80
experimental results with inaccuracy up to 15% for welds and X120 steel grade //Science and technology of welding & joining 2014;
which obtained at the HLAW of the low carbon low-alloy 19, 1: 15-24.
steels Х80-Х120 [10, 14]. [11] Tsibulskiy I., Kuznetsov M., Akhmetov A. Effect of Welding Position
and Gap between Samples on Hybrid Laser-Arc Welding Efficiency //
Applied Mechanics and Materials 2014; 682: 1-5.
Conclusions [12] Verhoeven J.D. Steel Metallurgy for Non-Metallurgists; 2007, 213p.
[13] Ohata M., Morimoto G., Fukuda Y., Minami F., Inose K., Handa T.
In this study set of experiments of HLAW X80 pipeline Prediction of ductile fracture path in Charpy V-notch specimen for laser
steel with high power fiber laser and welding wire MF 940M beam welds. Welding in the World 2015; 59, 5: 667- 674.
was conducted. Influence of the welding speed and preheating [14] Rethmeier M., Gook S., Gumenyuk A. Prospects of application of laser-
GMA hybrid welding for manufacturing of large diameter longitudinal
temperature on the cooling rate, microstructure, hardness,
welded high strength steel pipes. Proceedings of the VII International
tensile strength and impact energy was defined for welds with scientific and technical Conference “Beam technologies and laser
acceptable quality in the experiments. The main conclusions application” 2013; 130-140.
can be summarized in the following:

• Increase of the heat input and decrease of the preheating

temperature shows the increase in cooling rates, proportion