ISO/TR 10809-2:2011

TECHNICAL ISO/TR
REPORT 10809-2
First edition
2011-04-01
Cast irons —
Part 2:
Welding
Fontes —
Partie 2: Soudage
Reference number
©
ISO 2011
©  ISO 2011
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ii © ISO 2011 – All rights reserved

Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Metallurgy.1
3 Terms and definitions .2
4 Suitable welding processes .3
4.1 General .3
4.2 Oxy-acetylene gas welding (311).3
4.3 Arc welding (1).3
4.4 Gas-shielded metal arc welding (13/14) .5
4.5 Submerged arc welding (12) .5
4.6 Plasma arc welding with or without filler metal (15).6
4.7 Electron beam welding (511).7
4.8 Pressure welding processes (4) .7
4.9 Other welding processes.11
5 Suitable welding procedures .11
5.1 Welding with homogeneous filler metal.11
5.2 Welding with semi-homogeneous filler metal .13
5.3 Welding with non-homogeneous filler metal.13
5.4 Welding without filler metal.15
6 Examples of welding of cast irons .15
6.1 Welding of spheroidal graphite cast iron.15
6.2 Welding of grey cast iron.33
6.3 Welding of compacted graphite cast irons.34
6.4 Welding of malleable cast iron.34
6.5 Welding of abrasion resisting cast irons.36
6.6 Welding of austenitic cast irons .36
6.7 Welding of ausferritic spheroidal graphite cast irons.40
7 Summary data for the welding of cast irons .41
Bibliography.51

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
In exceptional circumstances, when a technical committee has collected data of a different kind from that
which is normally published as an International Standard (“state of the art”, for example), it may decide by a
simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely
informative in nature and does not have to be reviewed until the data it provides are considered to be no
longer valid or useful.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO/TR 10809-2 was prepared by Technical Committee ISO/TC 25, Cast irons and pig irons.
ISO/TR 10809 consists of the following parts, under the general title Cast irons:
⎯ Part 1: Materials and properties for design
⎯ Part 2: Welding
iv © ISO 2011 – All rights reserved

Introduction
Cast irons can be successfully welded, see References [4], [9], [10], [16], [17] in the Bibliography.
A precondition is that the welding is done professionally and with care.
It is intended that all welding of the different cast iron types and grades with themselves or with other ferrous
materials should be done by trained personnel, in accordance with appropriate standards and approved
procedures.
Technological advances in welding methods have contributed to a change of attitude with regard to welding
iron castings.
The designer needs to understand that the conditions/parameters which might need to be considered if
welding is to be carried out by a suitable welding process for either production or repair depend upon
⎯ the cast iron material,
⎯ the expected quality level of the weld,
⎯ the casting shape and size,
⎯ the welding application,
⎯ the welded joint, and
⎯ the filler metal(s), if required
Advancement of the state-of-the-art in welding of cast iron materials has been incorporated into International
and European Standards [1], [2], [3], [5] in the Bibliography.
Economic considerations should be taken into account when deciding on the suitability of welding a casting.
As an important precondition, the weld of the casting or the constructive unit should satisfy the requirements
to be agreed at the time of ordering between manufacturer and purchaser.
NOTE Currently, the best knowledge and most experience exist for malleable cast irons and spheroidal graphite
cast irons.
This part of ISO/TR 10809 gives design engineers knowledge as to whether or not it is possible to weld the
many types and grades of cast iron standardized in a number of international cast iron material standards

TECHNICAL REPORT ISO/TR 10809-2:2011(E)

Cast irons —
Part 2:
Welding
IMPORTANT — The electronic file of this document contains colours which are considered to be
useful for the correct understanding of the document. Users should therefore consider printing this
document using a colour printer.
1 Scope
The purpose of this part of ISO/TR 10809 is to assist the design engineer to understand and to acquire
knowledge of how the family of cast iron materials can be welded and to utilize this technology to its full
advantage in selecting the most appropriate technique for a particular cast iron. Because the application of
welding technology and the metallurgical implications of welding are not scientific disciplines normally taught
to engineering students, such users often have limited knowledge of the fundamentals underpinning welding
technology for cast irons. This part of ISO/TR 10809 explains what can be achieved, what cannot be achieved
and why. It is not designed to be a textbook of welding technology. It helps users to select the most
appropriate welding process and conditions for a specific application.
This part of ISO/TR 10809 covers production (including finishing and joint welding) and repair welding.
2 Metallurgy
The temperatures which occur during welding dissolve the graphite present in the liquid metallic matrix.
Depending on the carbon saturation of the melt and cooling rate of the weld, either martensite and/or
ledeburite is formed. In the case of ledeburite, it is formed in the molten areas after a very short time interval
(≤ 40 ms). Therefore, it is practically impossible to avoid the formation of ledeburite.
Both martensite and ledeburite are very hard and brittle. They prevent deformation under load, impede
machining of the weld and enhance the formation of welding cracks, unless suitable counter-measures are
taken.
With the application of appropriate welding processes (e.g. pressure-welding processes), ledeburite can be
removed totally from the welding groove, and the formation of martensite can be avoided by either preheating
the welding area or the whole casting. They can be completely removed or minimized if appropriate post-weld
annealing procedures are followed. To achieve these conditions, the material-specific interrelationships
between the base material and the weld material should be converted into production parameters, so as to
allow targeted and process-safe settings for the weld-seam characteristics.
The following major welding parameters/control variables are available.
a) Pre-heat temperature: To avoid martensite formation, the weld area should be pre-heated to
temperatures above the start temperature of martensite transformation. Pre-heating will not prevent the
formation of ledeburite.
b) Heat input: should be as low as possible during welding.
c) Welding speed: will vary depending upon the welding procedure applied and the chemical composition of
the cast iron type and grade.
d) Cooling curve: In principle, the required cooling curve can be determined from the time-transition-
temperature (TTT) diagram relevant to the cast iron material. For instance, continuously controlled
cooling according to the appropriate TTT diagram can prevent the formation of martensite, e.g. in a flash-
welding machine. When manual welding methods are used, the cooling rate is influenced by the selected
pre-heating temperature.
e) Welding procedure/welding parameter: for automated procedures.
f) Filler metal: When manual or mechanized welding-arc processes are used, the filler metal is matched
against the requirements of the weld or welded joint. This depends upon whether the welding process is
carried out with homogeneous, semi-homogeneous or non-homogeneous filler metal. No filler metals are
needed for the pressure-welding processes described later in the text.
g) Post-weld heat treatment: Measures can be undertaken to remove undesirable structures, such as:
⎯ martensite which can be removed by a sub-critical anneal (tempering);
⎯ ledeburite which can only be removed by a graphitization anneal at austenitizing temperature.
However, these control parameters are not independent of each other and have to be coordinated with the
welding procedure applied.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
production welding
any welding carried out during manufacturing before final delivery to the end user
NOTE Production welding includes finishing welding and joint welding.
3.1.1
finishing welding
production welding carried out in order to ensure the agreed quality of the casting
EXAMPLE Finishing welding is the elimination of discontinuities at the surface, e.g. gas pores, sand/slag inclusions,
unacceptable shrinkage cavities or cracks that impair the usability of the casting or substantially disturb the appearance of
the casting, and which therefore have to be removed during production and before the casting is delivered to the
customer.
3.1.2
joint welding
production welding used to assemble components together as an integral unit
EXAMPLE Joint welding is used when a casting is to be joined to another casting or component, e.g. sheet metal or
steel profile, to form a complex constructive unit. Welding is part of the manufacturing process and can either be carried
out in the foundry itself or at the facility of the processing subcontractor.
3.2
repair welding
welding carried out after final delivery of the casting to the end user
EXAMPLE A broken machine-column casting is causing substantial downtime and financial loss for the user. It
would take too long to procure a new casting and delay production for an unacceptably long time period. Repair welding of
the broken casting could solve the problem more quickly and economically.
2 © ISO 2011 – All rights reserved

4 Suitable welding processes
4.1 General
Five classes of welding process are described in the following subclauses:
⎯ arc welding, see 4.3.2, 4.3.3, 4.4.2, 4.4.3, 4.4.4, 4.5, 4.6, 4.8.2;
⎯ beam welding, see 4.7;
⎯ resistance welding, see 4.8.1;
⎯ oxy-acetylene gas welding, see 4.2;
⎯ welding with pressure, see 4.8.1, 4.8.2, 4.8.3.
[54]
NOTE ISO 4063 categorizes the welding process by a number. In this part of ISO/TR 10809, the number relating
to the welding-process follows the title of the clause.
4.2 Oxy-acetylene gas welding (311)
The oxy-acetylene gas welding process uses a manually operated flame as the heat source. The flame is
energized by a gaseous fuel mix of oxygen and acetylene, the oxygen being mixed with the acetylene inside
the burner. The flame is characterized by a two-stage combustion process which enhances the welding
process, especially that of providing a protective shield against the ambient atmosphere.
Homogeneous welding rods should preferably be used for oxy-acetylene welding with large output burners
having a neutral to slightly reduced flame setting. Fluxes designed to give a neutral atmosphere that prevent
oxidation and re-dissolve the oxides formed during pre-heating are either integrated into the welding rods as
grooves as a covering, or they are added separately. But also non-homogeneous filler metals are utilized.
Data on mechanical properties of welds can be found in Reference [8] in the Bibliography.
4.3 Arc welding (1)
4.3.1 General
The process uses electrically generated welding heat with either homogeneous, semi-homogeneous or non-
homogeneous filler rods to make the weld.
The electrical arc has a core temperature of between 5 300 K and 6 000 K. The arc is struck between the
surface of the component to be welded and the consumable filler rod.
The coating on the electrode has several uses:
⎯ protection against the atmosphere; the droplets of metal in the arc are protected by a cover of slag or
protective gas;
⎯ easier ignition of the arc;
⎯ solid arc by ionization of the air column;
⎯ alloying of the weld deposit;
⎯ covering of the weld seam during cooling;
⎯ increasing the deposition rate by adding iron powder;
⎯ modification of the welding characteristic for such properties as current, polarity, weld shape, basicity and
amperage.
[2]
Manual arc welding is the preferred procedure using covered electrodes (see ISO 1071 ) with a pure nickel
or nickel-iron core wire. Data on mechanical properties can be found in Reference [8] in the Bibliography. For
certain applications, Ni-Cu, Cu-AI and Cu-Sn alloys have been used successfully.
The welding parameters chosen should ensure a narrow heat-affected zone with small amounts of hard
structure. Interconnected martensitic and/or ledeburitic transition and heat-affected zones are particularly
unfavourable as they induce residual stresses in the casting. Island-like distribution induces less stress in the
welded area of the casting. Residual stress can be minimized by adopting some or all of the following
measures, see Reference [15] in the Bibliography:
⎯ using electrodes with the smallest possible core-wire diameter;
⎯ using the lowest possible welding current to generate a short arc;
⎯ depositing short stringer beads of 20 mm to 30 mm length with a low cross-section;
⎯ allowing sufficient cooling time between the individual beads;
⎯ changing the welding direction between the individual layers;
⎯ holding the electrode vertically.
4.3.2 Metal arc welding with covered electrodes (111)
In order to fill the weld as quickly as possible and to maintain a constant pre-heating temperature as far as
possible, metal arc welding with large-diameter covered electrodes in conjunction with a high current (up to
1 500 A) is chosen. For welding spheroidal graphite cast irons, the covered electrodes can consist of a cored
rod of spheroidal graphite cast iron or steel. When a steel rod is used, carbon and silicon as well as elements
required for spheroidal graphite formation, such as magnesium, cerium or other rare earths are added from
the weld rod coating. Spheroidal graphite cast-iron rods used for oxy-acetylene welding can also be used.
Since the magnesium contained in these rods, which is required for spheroidization, is prone to evaporate in
the arc, covered electrodes or unalloyed core wires are preferred to reduce the susceptibility to graphite
degeneration. An overview of the requirements for welding materials and the design of welding rods and
covered electrodes can be found in Reference [2] in the Bibliography.
4.3.3 Self-shielded tubular-cored arc welding (114)
Due to the outside cover and the length of the electrodes, limits have to be set for manual metal arc welding
concerning the degree of mechanization and, with it, the possible improved efficiency. Continuously fed
electrodes offer essential increased efficiency.
Suitable welding processes are
⎯ gas-shielded metal arc welding with bare electrodes, and
⎯ submerged arc welding with bare electrodes.
The following self-shielded tubular-cored electrodes are the state-of-the-art:
⎯ self-shielded tubular-cored wire electrodes used with or without gas protection. When welding without gas
protection, the slag formers are positioned in the middle of the electrode wire. An excess of deoxidizer
should be present;
⎯ gas-shielded (CO ) with bare wire electrodes.
Metal arc welding with flux-cored wire electrodes is gaining more and more in importance for economic
reasons, because the process can be automated. The process has a high weld-metal recovery and provides
numerous alloying possibilities. Since high pre-heating temperatures can cause thermal distortion, self-
shielding flux-cored wires are used instead of shielding gas.
4 © ISO 2011 – All rights reserved

4.4 Gas-shielded metal arc welding (13/14)
4.4.1 General
The TIG (Tungsten lnert Gas), MIG (Metal lnert Gas) and MAG (Metal Active Gas) processes have special
advantages by welding with non-homogeneous filler metal, due to the high energy density of their gas-
shielded arcs and the associated narrow heat-affected zone.
4.4.2 Tungsten inert gas welding — (TIG welding) (141)
The arc burns between the unconsumed tungsten electrode and the work piece under the protection of an
inert gas. This protective gas flows through a gas jet and protects the electrode and the weld against air
ingress. Inert gases, such as Argon (Ar) and Helium (He), or mixtures of both gases, protect the tungsten
electrode. Oxidizing protection gases, e.g. O or CO , cannot be used. However, when welding certain
2 2
metals, small percentages of H are sometimes added. The process lends itself to part or full mechanization
with or without filler metal welding. Welding rods or wire are normally added with the power off.
4.4.3 Metal inert gas welding — (MIG welding) (131/132/133)
As a general rule, the arc burns between a positive consumable welding wire and the work piece under a
streaming inert gas inside an inert gas jacket. The protection gases are the same as those used for TIG
welding. Inert gases, even with the high temperature of the arc, do not react with the weld. MIG welding is
suitable for the welding of Aluminium (Al) and Magnesium (Mg) and their alloys.
The MIG/MAG processes can be used for joint welding, and when they are automated, it is possible to use
them for large-scale joint-welding production. The MIG/MAG processes are increasingly used for hard facing
(repair welding), finishing welding and general repair welding. By reducing the heat input through the adoption
of short-arc and impulse technology, extremely narrow heat-affected zones result, with improved mechanical
properties as shown in Reference [9] in the Bibliography. The main shielding gas used is argon. Today, only
small amounts of CO are recommended for MAG welding. A higher CO content is considered problematic
2 2
with regard to its oxidizing effect on magnesium and, as a possible consequence, the degeneration of graphite
in cast iron.
4.4.4 Metal active gas welding — (MAG welding) (135/136/138)
Compared to MIG welding, the only difference in the welding process is that the inert gas is replaced by active
gases such as CO , mixtures of either Ar and CO or Ar, CO and O . The same welding equipment is used
2 2 2 2
for both MIG and MAG welding. The arc burns with the protection of an active gas between the consumable
welding wire and the work piece. When using equal current and voltage, the protection gases have an effect
on the arc shape, the length of the arc and the upper and lower welding beads.
Figure 1 illustrates the bending fatigue strength of un-welded and welded ferritic (left picture) and pearlitic
(right picture) spheroidal graphite cast iron. These results are quite well in accordance with the results of
blackheart malleable cast irons of the same strength category (References [10], [11] in the Bibliography).
4.5 Submerged arc welding (12)
Submerged arc welding is a masked arc welding process. The arc burns between the consumable wire
electrode and the work piece. The arc is protected by a loosely (not fixed) filled granular, easily fluxed powder.
Sparks and spatter are prevented by this technique. The powder protects the weld pool against air ingress,
avoids abrupt cooling, shapes the weld and assists gas emission from the weld metal. It also has a
metallurgical influence on the chemical composition of the weld metal.
Submerged arc welding, electro-slag welding with solid or flux-cored wire, cast welding or liquid metal welding
are mainly used for repair welding of large castings.
Figure 1 — Bending fatigue strength of un-welded and welded ferritic (left) and
pearlitic (right) spheroidal graphite cast iron
Figure 1 is reproduced by permission of Bundesverband der Deutschen Giesserei-Industrie, Dusseldorf.
4.6 Plasma arc welding with or without filler metal (15)
Plasma welding is operated by a heavily heated gas consisting of molecules, atoms, ions and electrons. It is
entirely electrically neutral.
Two different arc arrangements are used, an auxiliary arc and an assigned arc. The auxiliary arc is used to
ignite the assigned arc. The auxiliary arc is induced by high-frequency current. If the assigned arc is ignited
then the auxiliary arc extinguishes. The assigned arc burns between a non-consumptive thoriated tungsten
electrode and the work piece. A water-cooled strangling copper injector is the anode and a Ti-electrode is the
cathode. The plasma gas is blown into the annulus collector between the anode and the cathode. The Cu-
injector effects a lateral contraction of the arc, thus an improvement of power density and accordingly an
increase of temperature of the plasma beam. Adjustments allow the process to be used for either welding or
cutting.
For plasma arc joint welding, in addition to the plasma gas, a second gas stream (99,95 % Ar) is used in order
to protect the weld pool against atmospheric interference.
Most plasma arc welding equipment uses a third gas stream, the focussing gas (Ar + He, Ar + H , Ar + N ) for
2 2
additional compressing of the plasma stream outside the strangling injector.
Plasma welding with or without filler metal is mostly an application-orientated procedure, e.g. for pipe joints
(see Figure 2).
6 © ISO 2011 – All rights reserved

Figure 2 — Plasma welded joint between a centrifugal casting tube and
a spheroidal graphite cast iron (JS) flange
Figure 2 is reproduced by permission of Bundesverband der Deutschen Giesserei-Industrie, Dusseldorf.
4.7 Electron beam welding (511)
When energy conservation is sought, electron beam welding should be considered as an alternative welding
method (Reference [10] in the Bibliography). Electron beam welding has a very favourable heat input. Welding
without filler metal showed unsatisfactory results. However, by adding a nickel inlay, the hardened zones in
the area of parent metal were reduced to a minimum. Due to the procedural complexity, electron beam
welding will very probably remain limited to certain special applications.
4.8 Pressure welding processes (4)
4.8.1 Flash welding (24)
Pressure welding processes use the application of heat and pressure to give macro-deformation and
coalescence of the base material. Flash welding is a resistance pressure-welding process. The welding heat
is generated by resistance heating directly in the welding unit by induced current. The parts are repeatedly
pressed together, such that the contact faces are heated by the flashing (sometimes referred to as arcing) of
the welding current. The process is reversed (repeated) until the energy at the contact faces is sufficient to
achieve continuous flashing.
During the flashing phase, “fusing contacts” develop where the ends of the electrically charged parts are
brought together. The extremely high current created in the transition zone quickly heats and melts the metal.
The high resistance caused by insufficient compressing of the contact faces increases the deposition rate of
the weld. Vapour pressure builds up on the weld surface as a result of metal evaporating in some areas. Due
to vapour pressure, liquid metal is thrown out of the welding gap, creating a “shielding gas atmosphere” that
keeps the atmospheric oxygen away from the weld. The flashing process is continued until the required
welding temperature is reached. Then the machine control starts the upsetting process, followed by switching
off the electric current.
Large, thick-walled castings are usually welded after pre-heating. Thin-walled castings do not normally require
“reversing”. The process is then called flash welding without pre-heating, or “cold flash welding”.
Modern welding machines can provide a resistance post-weld heat treatment while the parts are still in the
machine, thus avoiding intermediate cooling with the potential risk of creating martensitic structures prone to
cracks.
The flash-welding process is divided into the following steps:
⎯ initial flashing to produce parallel surfaces;
⎯ flashing to generate sufficient heat for the upsetting operation;
⎯ upsetting to compress two surfaces to form the joint and press out ledeburite from the weld zone;
⎯ controlled cooling, post-weld, to prevent the formation of martensite and to produce the required structure
(References [12], [13], [14] and [40] in the Bibliography).
Figures 12, 14 and 15 illustrate the process sequences and the process monitoring (see 6.1.2.2).
4.8.2 Magnetically impelled arc welding (185)
TM
Welding with a magnetically impelled arc, sometimes referred to as Magnetarc welding, is an arc pressure-
welding process that makes use of the fact that an arc can be deflected in various directions by a controlled
magnetic field. Depending on the direction and intensity of the magnetic field, the arc can be rotated around its
own axis, or programmed to take an elliptic shape of varying current density. In most cases, the electric arc
moves between two tubes.
Welding is carried out with fully mechanized or automated welding equipment. The work pieces are centred
and clamped in the machine, and the arc is struck as soon as the two faces to be joined touch. The arc is then
rotated between the abutting faces with increasing speed, thereby melting them. Direct current is used for this
welding process. The rotational speed is between 30 m/s and 150 m/s, depending on the strength of current,
magnetic field and shielding gas used, which equals a rotational frequency of between 200 Hz and 2 000 Hz.
After a predetermined period of time, the two components are pressed together, and then the welding current
is switched off.
Figure 3 — Successive process steps of magnetically impelled arc welding
Figure 3 is reproduced by permission of KUKA Systems GmbH Industrial Solutions, Augsburg.
8 © ISO 2011 – All rights reserved

Examples of the ranges of the process parameters:
⎯ Strength of current: 200 A to 1 200 A ⎯ Upsetting force: 0,5 kN to 450 kN
⎯ Welding time: 0,3 s to 5 s ⎯ Magnetic field: 100 G to 500 G
⎯ Length of arc: 1,5 mm to 3 mm ⎯ Shielding gas: Mainly CO
4.8.3 Friction welding (42)
Friction welding belongs to the group of hot pressure-welding processes. Heat generated by friction due to the
relative motion of the contact faces allows joining under a compressive load. Here a distinction is necessary
between conventional- and inertia-friction welding. During conventional-friction welding, powerful electric
motors accelerate and stop the rotating component. During inertia-friction welding, the applied thermal energy
is supplied by the mass and speed of the flywheel.
Friction welding can be successfully achieved by using the right combination and sequence of contact
pressure and/or number of revolutions during welding. State-of-the-art control systems are used to provide a
practically unlimited choice of pressure/speed curves. Changes in pressure or speed can be planned
continuously or step by step. Typically, speeds range from approximately 500 to 3 000 r/min, with pressures
2 2
varying between 20 N/mm and 100 N/mm . When the joining faces have been heated sufficiently, the
rotational movement of the friction spindle is decelerated abruptly to start the upsetting phase, and the two
parts to be joined are forged together. Upsetting may be effected either while the spindle is still rotating with a
defined speed, or into the spindle. The upsetting pressures applied are generally above the friction pressures
needed to create the friction.
Figure 4 shows the successive process steps of friction welding.

Phase 1: Two pieces are clamped, rotation of one
work piece
b) Phase 2: Heating: Two work pieces are
pressed together with force F (friction force)
Rotation n and force F generate friction; the
surfaces to be welded are heated
c) Phase 3: Welding: Rotation of the work piece
is slowed down (selectable deceleration time),
joining by increased force F , upsetting force
Figure 4 — Process phases of friction welding
Figure 4 is reproduced by permission of KUKA Systems GmbH Industrial Solutions, Augsburg.
Rotational symmetry is an important design consideration for friction welded components. Non-rotationally
symmetrical parts can be joined with minimum angular deviation, but the process is not recommended.
The advantages of friction welding include the following:
⎯ friction welding allows successful joining of most dissimilar materials;
⎯ joining two identical materials is usually possible without any limitation in the wall thickness, i.e. up to the
full cross-section;
⎯ the welding times are short and range between 10 s and 30 s;
⎯ no filler metal is required for welding.
A significant restriction is that friction welding of dissimilar materials is often limited to hollow profiles. Other
restrictions to friction welding include the following:
⎯ for cast-iron materials, the wall thickness is limited by the need to squeeze out the ledeburite formed
during the process, see 6.1 2.
Defining process parameters is more complex compared to welding with an input of electric energy.
Parameters are based on carefully established, extensive data banks and experience gained over many years
and through numerous trials. Machine and process reproducibility requires process parameters to be logged,
evaluated and documented by appropriate control systems, which can range from simple analogue systems
as shown in Figure 5 to fully graphic, computer-based systems as shown in Figure 6.
Figure 5 — Time curve of process parameters of speed n, friction/upsetting pressure p, travel s
Figure 5 is reproduced by permission of KUKA Systems GmbH Industrial Solutions, Augsburg.
10 © ISO 2011 – All rights reserved

Figure 6 — Friction welding — Process monitoring with PC-based fully graphic systems
Figure 6 is reproduced by permission of KUKA Systems GmbH Industrial Solutions, Augsburg.
4.9 Other welding processes
Other welding processes are cast welding and liquid metal welding:
⎯ cast welding: welding by pouring liquid metal into a specially prepared groove in a casting (Reference [1]
in the Bibliography);
⎯ liquid metal welding: welding with additional use of a metal arc welding process (Reference [1] in the
Bibliography).
5 Suitable welding procedures
NOTE The specification of the requirement class and selection of the assessment group is the basis for the selection
of the suitable welding procedure and any special conditions or considerations that apply (Reference [51] in the
Bibliography). The following subclauses 5.1 to 5.4 give information on the suitable welding procedures and show
examples related to the welding of cast irons.
5.1 Welding with homogeneous filler metal
Homogeneous filler metal comprises any filler which results in a deposited metal with the same type of
microstructure as the parent metal (Reference [2] in the Bibliography).
Figure 7 shows an example of a cast-iron weldment produced with homogeneous filler metal, i.e. an iron
matrix containing graphite.
Figure 7 — Microstructure of the transition zone Figure 8 — Typical microstructure of a
of a weld produced with a homogeneous transition zone of a non-homogeneous weld of
Fe-C-Si filler metal (right side of photograph) a spheroidal graphite cast-iron grade
on a JS/400-15 casting (left side of photograph) ISO1083/JS/400-15 (left)
material with Ni-Fe filler metal (right) (see 5.3)
Figures 7 and 8 are reproduced by permission of Siempelkamp Giesserei GmbH, Krefeld.
To prevent the formation of martensite and/or bainite, the entire casting (in some cases just the weld) should
be pre-heated. Pre-heating has the same effect as delayed cooling. The pre-heating temperature should
range from 400 °C to 700 °C (References [6] and [7] in the Bibliography), depending on the type and grade of
cast iron. During welding, the working temperature should be monitored and maintained within the limits given
in the tables in Clause 7. An increased working temperature and the small solidification interval of cast irons
form a much higher risk of the weld pool collapsing. In such circumstances, a weld-pool backing support
needs to be used. If necessary, heat treatment can be carried out after welding to produce the required
material structure and the casting should be sufficiently slow cooled to reduce residual stress.
Suitable welding processes used with homogeneous filler metals are
⎯ self-shielded tubular-cored arc welding with wire electrodes without gas protection,
⎯ manual metal arc welding with covered electrodes,
⎯ oxy-acetylene gas welding,
⎯ cast welding, and
⎯ liquid metal welding.
In all five cases, welding should be carried out with the greatest possible heat input.
[2]
Suitable welding consumables should be chosen from those given in ISO 1071 .
Homogeneous welding rods should be used for oxy-acetylene welding with large output burners having a
neutral to slightly reduced flame setting. Fluxes designed to give a neutral atmosphere that prevent oxidation
and re-dissolve the oxides formed during pre-heating are either integrated into the welding rods as grooves,
as a covering, or they are added separately.
Solution annealing heat treatment can also then be necessary if additional elongation properties are required
(Reference [7] in the Bibliography).
12 © ISO 2011 – All rights reserved

5.2 Welding with semi-homogeneous filler metal
Semi-homogeneous filler metal is any filler metal which results in a deposited metal with a steel-type
microstructure, i.e. without any graphite being present (Reference [2] in the Bibliography). Welding with semi-
homogeneous filler metal is only suitable for malleable cast irons and spheroidal graphite cast irons.
Some authors report on the use of steel electrodes for spheroidal graphite cast irons (Reference [28] in the
Bibliography). To avoid cracks in the weld transition area, the weld temperature parameters need to be
controlled and kept within close limits. Martensite should be removed by annealing to produce highly ductile
welded joints. Pre-heating temperatures of 250 °C to 550 °C can considerably reduce the formation of
martensite after welding. Reference [8] in the Bibliography contains typical mechanical properties.
5.3 Welding with non-homogeneous filler metal
A non-homogeneous filler metal is any filler metal which results in a deposited weld metal with a
microstructure that differs from the parent metal (Reference [2] in the Bibliography).
Suitable welding processes are as follows:
⎯ Manual metal arc welding with covered electrodes and filler metals with pure nickel or nickel/iron wire.
(For certain applications Ni/Al, Cu/Al, Cu/Sn alloys have successfully been used);
⎯ Tungsten Inert Gas welding (TIG);
⎯ Metal Inert Gas welding (MIG);
⎯ Metal Active Gas welding (MAG).
Welding with non-homogeneous filler metals, such as the high-nickel materials, produces a weld with a
microstructure that differs from the parent metal (Reference [2] in the Bibliography) i.e. the matrix may be
largely free from iron. In this case, the obvious distinguishing feature compared to that of a homogeneous filler
metal is the difference in colour between the austenitic filler metal and the parent metal. In the dilution zone,
the nickel-based filler metal picks up iron from the parent metal to form nickel martensite. During solidification,
carbon precipitates in the form of small graphite spherulites, which results in a reduction of residual stress due
to the increase in volume caused by the precipitation of graphite. The weld remains tough. Shot peening the
weld while hot can even create advantageous compressive stresses that minimize the risk of residual stress
from the welding procedure.
The typical microstructure of the transition zone of a non-homogeneous weld of an ISO1083/JS/400-15
material with Ni-Fe filler metal is shown in Figure 8, see 5.1.
For nickel-based weld metal, there is normally no need to pre-heat the casting. For welding procedures with a
higher energy density, such as gas-shielded metal arc welding or manual arc welding with larger electrode
diameters, pre-heating to 100 °C to 250 °C is recommended. The continuous martensitic seam caused by the
higher specific heat input can thus be avoided but not the nickel martensite in the fusion zone or the ledeburite
normally surrounding the graphite spherulites [see Figures 9 a), 9 b) and 9 c)].
a)  Welding structure of a b)  Welding structure of a c)  Welding structure of a multi-
transition zone of spheroidal transition zone of spheroidal pass weld: Influenced by the
graphite cast iron welded with a graphite cast iron welded welding heat the ledeburite isles
Ni-Cu filler metal, not preheated: with a Fe-Ni filler metal, of the lower layers have been
Transition zone with ledeburite preheated to 350 °C: transformed to pearlite and tiny
and Ni-martensite Transition zone with spherulites with surrounding
Ledeburite and Ni-Martensite ferrite
Figure 9 — Welded structures with spheroidal graphite cast iron
Figure 9 is reproduced by permission of Georg Fischer Automotive AG, Schaffhausen.
The higher the heat input, the larger the ledeburite islands which, in extreme cases, can expand to form a
continuous seam. Because ledeburite has practically no deformability and only decomposes at higher
annealing temperatures and longer annealing times, the lowest possible heat input should be applied when
welding graphite containing cast iron with non-homogeneous filler metal. For multi-layer welding, the upper
layers can have a heat-treatment effect upon the lower ones [see Figure 9 c)].
The slower solidification rate of thick-walled cast irons results in fewer, but larger graphite inclusions. The
increased distance between the graphite inclusions prevents the ledeburite islands from merging. The
tendency to form a ductile melting line is therefore higher than in thin-walled castings, which consequently
produces welds with a reduced risk of brittle fracture, even without post-heat treatment.
Cast iron with a ferritic matrix is easier to weld than cast iron with a pearlitic matrix. This is
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