ISO 15620:2000

INTERNATIONAL ISO
STANDARD 15620
First edition
2000-07-15
Welding — Friction welding of metallic
materials
Soudage — Soudage par friction des matériaux métalliques
Reference number
©
ISO 2000
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ii © ISO 2000 – All rights reserved

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 3.
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 member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 15620 was prepared by the European Committee for Standardization (CEN) in
collaboration with ISO Technical Committee TC 44, Welding and allied processes, Subcommittee SC 10, Unification
of requirements in the field of metal working, in accordance with the Agreement on technical cooperation between
ISO and CEN (Vienna Agreement).
Throughout the text of this standard, read ".this European Standard." to mean ".this International Standard.".
Annexes A to H of this International Standard are for information only.
For the purposes of this International Standard, the CEN annex regarding fulfilment of European Council Directives
has been removed.
Contents
Page
Foreword v
............................................................................................................................................................................
Introduction vi
......................................................................................................................................................................
1 Scope 1
.........................................................................................................................................................................
2 Normative references 1
..............................................................................................................................................
3 Terms and definitions 1
..............................................................................................................................................
4 Welding knowledge 4
..................................................................................................................................................
4.1 Process 4
.......................................................................................................................................................................
4.2 Materials and material combinations 7
.........................................................................................................................
4.3 Friction welding machines 7
..........................................................................................................................................
5 Quality requirements 9
...............................................................................................................................................
5.1 General 9
.......................................................................................................................................................................
5.2 Pre-welding conditions 9
...............................................................................................................................................
5.3 Post-welding treatment 10
.............................................................................................................................................
5.4 Quality assurance 10
.....................................................................................................................................................
6 Welding procedure specification (WPS) 11
..............................................................................................................
6.1 General 11
.....................................................................................................................................................................
6.2 Information related to the manufacturer 11
...................................................................................................................
6.3 Information related to the material 11
...........................................................................................................................
6.4 Welding parameters 11
.................................................................................................................................................
6.5 Joint 12
..........................................................................................................................................................................
6.6 Optional devices 12
.......................................................................................................................................................
7 Welding procedure approval 12
................................................................................................................................
7.1 Principles 12
..................................................................................................................................................................
7.2 Welding procedure tests 12
..........................................................................................................................................
7.3 Welding procedure approval record (WPAR) 16
..........................................................................................................
7.4 Previous experience 16
.................................................................................................................................................
7.5 Circumstances mandating requalification 16
................................................................................................................
7.6 Machine-specific nature of a WPS 16
..........................................................................................................................
7.7 Requalification procedure requirements 16
..................................................................................................................
8 Welding personnel 16
.................................................................................................................................................
8.1 Friction welding machine operator 16
...........................................................................................................................
8.2 Friction welding machine setter 16
...............................................................................................................................
8.3 Welding coordination personnel (supervisor) 16
..........................................................................................................
(informative)
Annex A – Relationship of welding parameters 17
....................................................................................
Annex B (informative) – Additional processes based on friction 19
...............................................................................
(informative)
Annex C – Material combinations weldable by friction welding 21
..........................................................
Annex D (informative) – Guidelines for quality assurance 22
..........................................................................................
(informative)
Annex E – Examination and test 23
..............................................................................................................
Annex F (informative) – Manufacturer's friction welding procedure specification (WPS) 25
......................................
Annex G (informative) – Characteristics of friction welded components 27
..................................................................
Annex H (informative) – Welding procedure approval record form (WPAR) 31
..............................................................
iv © ISO 2000 – All rights reserved

Foreword
The text of EN ISO 15620:2000 has been prepared by Technical Committee CEN/TC 121 "Welding", the secretariat of
which is held by DS, in collaboration with Technical Committee ISO/TC 44 "Welding and allied processes".
This European Standard shall be given the status of a national standard, either by publication of an identical text or by
endorsement, at the latest by January 2001, and conflicting national standards shall be withdrawn at the latest by
January 2001.
This European Standard has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EU Directive(s).
For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this standard.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries
are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany,
Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United
Kingdom.
Introduction
Friction welding is a method for making welds in the solid phase in which one component is moved relative to and in
pressure contact with the mating component to produce heat at the faying surfaces, the weld being completed by the
application of a force during or after the cessation of relative motion. There are several forms of supplying energy and
various forms of relative movements.
The generation of friction heating results in a comparatively low joining temperature at the interface. This is largely the
reason why friction welding is suitable for materials and material combinations which are otherwise difficult to weld. The
weld region is generally narrow and normally has a refined microstructure.
Whilst the friction welding process deals primarily with components of circular cross section it does not preclude the
joining of other component shapes.
vi © ISO 2000 – All rights reserved

1 Scope
This standard specifies requirements for the friction welding of components manufactured from metals.
It specifies requirements particular to rotational friction welding related to welding knowledge, quality requirements,
welding procedure specification, welding procedure approval and welding personnel.
This standard is appropriate where a contract, an application standard or regulatory requirement requires the
demonstration of the manufacturer' s capability to produce welded constructions of a specified quality. It has been
prepared in a comprehensive manner to be used as a reference in contracts. The requirements given may be
adopted in full or some may be deleted, if not relevant to the construction concerned.
2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed hereafter. For
dated references, subsequent amendments to or revisions of any of these publications apply to this European
Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the
publication referred to applies (including amendments).
EN 1289
Non-destructive examination of welds – Penetrant testing of welds – Acceptance levels
EN 1290
Non-destructive examination of welds – Magnetic particle examination of welds
EN 1711
Non-destructive examination of welds – Eddy current examination of welds by complex plane analysis
EN ISO 4063
Welding and allied processes – Nomenclature of processes and reference numbers (ISO 4063:1998)
3 Terms and definitions
For the purposes of this standard, the following terms and definitions apply.
3.1
axial force
Axial force between components to be welded.
3.2
axial pressure
Pressure (force per unit area) on the faying surfaces.
3.3
burn-off length
Loss of length in the friction phase.
3.4
burn-off rate
The rate of shortening of the components during application of the friction force.
3.5
component
A single item before welding.
3.6
component induced braking
Reduction in rotational speed resulting from friction between the interfaces.
3.7
contact force
Axial force on contact of components.
3.8
contact torque
Reaction torque after friction start.
3.9
external braking
External braking reducing the rotational speed.
3.10
faying surface
A surface of one component that is to be in contact with a surface of another component to form a joint.
3.11
forge force
The force applied normal to the faying surfaces at the time when relative movement between the components is
ceasing or has ceased.
3.12
forge length
The amount by which the overall length of the components is reduced during the application of the forge force.
3.13
forge phase
In the friction welding cycle the interval between the start and finish of application of the forge force.
3.14
forge pressure
The pressure (force per unit area) on the faying surfaces resulting from the axial forge force.
3.15
forge rate
The rate of shortening of the components during the application of forge force.
3.16
forge time
The time for which the forge force is applied to the components.
3.17
friction force(s)
The force(s) applied normal to the faying surfaces during the time that there is relative movement between the
components.
3.18
friction phase
In the friction welding cycle the interval in which the heat necessary for making a weld is generated by relative
motion and the friction force(s) between the components, i.e. from contact of components to the start of
deceleration.
3.19
friction pressure(s)
The pressure(s) (force per unit area) on the faying surfaces resulting from the axial friction force.
3.20
friction time
The time during which relative movement between the components takes place at rotational speed and under
application of the friction force(s).
3.21
interface
The contact area developed between the faying surfaces after completion of the welding operation.
3.22
length allowance
Extra material to allow for loss of length.
3.23
overhang
The distance a component projects from the fixture, or chuck in the direction of the mating component.
2 © ISO 2000 – All rights reserved

3.24
peripherial velocity
Velocity of outer diameter of faying surfaces to be welded.
3.25
rotational speed
Revolutions per minute of rotating component.
3.26
stopping phase
In the friction welding cycle the interval in which the relative motion of the components is decelerated to zero.
3.27
stopping time
The time required by the moving component to decelerate from friction speed to zero speed.
3.28
torque curve
Torque characteristic between the two interfaces based on time (contact, equilibrium, final torque).
3.29
total length loss (upset)
The loss of length that occurs as a result of friction welding, i.e. the sum of the burn-off length and the forge length.
3.30
total weld time
Time elapsed between component contact and end of forging phase.
3.31
upset metal (flash)
Parent metal proud of the normal surfaces of the weldment as a result of friction welding.
3.32
weld cross-section
The areas to be welded.
3.33
welding cycle
The succession of operations effected by the machine for making a weldment and the return to the initial position
(excluding component-handling operations).
3.34
weldment
Two or more components joined by welding.
3.35
pressure contact area
The surface contact area of the components through which the force is transmitted.
4 Welding knowledge
4.1 Process
The classification of friction welding processes are listed in table 1.
Table 1 - Classification of friction welding processes
Friction welding
Relative motion classification Energy classification
Continuous drive
Stored energy
The process variant where The process variant where
power or energy is provi- the energy for welding is
ded by an infinite duration supplied by the kinetic
source and maintained for energy stored in a rotating
a preset period system or fluid storage
system
Hybrid system
Combining some features of both methods
Rotational Linear Angular
Orbital
reciprocation oscillation
A method in which one A method in which one A method in which one A method in which one
component is rotated rela- component is moved in a component is moved in an component is moved in a
tive to and in contact with linear oscillating motion angular oscillating motion small circular motion rela-
the mating face of another relative to and in contact about a common compo- tive to and in contact with
component or components. with thematingfaceof nent axis relative to and in the mating face of another
another component. contact with the mating component.
face of another compo-
nent.
4 © ISO 2000 – All rights reserved

4.1.1 Direct drive rotational friction welding
The energy input is provided by direct drive at predetermined rotational speed or speeds, figures 1 and 2.
1Drivemotor
2Brake
3a Rotating clamp
3b Stationary clamp
4a Rotating workpiece
4b Stationary workpiece
5 Forge cylinder
Figure 1 - Diagram showing direct drive rotational friction welding
1Axialforce 1) Burn-off length
2 Axial displacement 2) Friction time
3 Rotational speed 3) Stopping time
4 Friction phase 4) Forge time
5 Friction force 5) Forge length
6 Stopping phase 6) Total length loss (upset)
7 Forge phase
8 Forge force
Figure 2 - Diagram showing typical relationships of characteristics for friction welding at constant
rotational speed (friction welding, process No. 42 in accordance with EN ISO 4063)
The spindle is either decelerated at a predetermined rate or stopped by external braking or component induced
braking. The main welding parameters are listed below and their relationship is given in Annex A:
– rotational speed(s);
– predetermined friction force(s);
– friction time or burn-off;
– predetermined forge force(s);
– forge time;
– stopping time and forge delay.
4.1.2 Stored energy (inertia) friction welding
Energy stored in an inertia mass is used up in the friction welding process by component induced braking, see
figures 3 and 4.
1Drivemotor
2 Inertia mass, variable
3a Rotating clamp
3b Stationary clamp
4a Rotating workpiece
4b Stationary workpiece
5 Forge cylinder
Figure 3 - Diagram showing inertia friction welding
1Axialforce 1) Total length loss (upset)
2 Axial displacement 2) Friction time
3 Rotational speed 3) Forge time
4 Friction phase
5 Friction force
6 Forge phase
7 Forge force
Figure 4 - Diagram showing typical relationships of characteristics for inertia friction welding
(friction welding, process No. 42 in accordance with EN ISO 4063)
The main welding parameters are listed below and their relationship is given in Annex A:
– rotational speed;
– inertia mass;
– predetermined friction force(s);
– predetermined forge force(s).
6 © ISO 2000 – All rights reserved

4.1.3 Further processes
Further processes are listed in Annex B.
4.1.4 Friction welding arrangements
The following methods of rotational friction welding (see figure 5) can be distinguished:
– friction welding with the rotation of one of the components to be welded or one of the parts to be joined and
linear movement of the other (figure 5a) i.e. fixed head friction welding machine;
– welding with rotation and linear movement of one of the components to be welded and the other one held
static (figure 5b) i.e. sliding head friction welding machine;
– rotation and linear movement of two components against a static middle component (figure 5c) i.e. double
ended friction welding machine;
– rotation of central component with linear movement of two end components (figure 5d).
Figure 5a Figure 5b Figure 5c Figure 5d
Figure 5 - Rotational friction welding methods
4.2 Materials and material combinations
Experience of friction welding many metallic materials and combinations is already well-documented (see Annex C).
Weldability criteria for other welding processes is not always valid for friction welding. More materials and their
combinations can be friction welded when compared with most other welding processes. The data shown in
Annex C is based upon actual experience from test welds but it is not necessarily complete. For many materials and
material combinations there is further data available which is only valid for particular geometries.
The following factors can affect welding quality:
– amount, distribution and shape of non-metallic inclusions in the parent material(s);
– formation of intermetallic phases in the weld;
– formation of low melting point phases in the weld;
– porosity in parent material(s);
– thermal softening of hardened materials in the weld;
– hardening of the weld metal heat affected zone;
– hydrogen in parent material(s).
It may be possible to negate some of the above by critical selection of parameters or heat treatment.
4.3 Friction welding machines
4.3.1 General
Friction welding is not positionally sensitive and may be performed in any plane.
Machine design and build are dependent upon the welding application and there are preconditions for exact and
repeatable production. A schematic diagram of a horizontal friction welding machine is shown in figure 6.
1 Machine frame 7 Flash removal unit
2 Headstock with drive spindle and brake 8 Safety guards
3 Chuck - for rotating component 9 Hydraulic power pack - not shown
4 Clamp - for fixed component 10 Electrical control cabinet - not shown
5 Machine slides (tie-bars) 11 Machine control panel
6 Force actuator
Figure 6 - Schematic diagram of a direct drive friction welding machine of horizontal configuration
The application determines the choice of axial force(s), rotation speed(s) and welding time. Other parameters which
affect machine design are carriage speed during friction, friction burn-off, brake point, forging point, torque and
moment of inertia of the rotating mass.
The repeatability and variation of machine parameters should be checked while the machine is running at operating
temperature.
The machine should be of a specification appropriate to the parts to be welded.
The machine should be equipped with an automatic control system which, after the components have been
clamped in their work-holding devices and on initiation of the cycle, will undertake a controlled welding cycle without
intervention from the operator and will incorporate at least the following operational cycle:
– initiation of a sequence which will bring the components into face contact at a chosen rotational speed;
– establishment and the maintenance of a friction force(s) and relative speed(s) for the duration of the heating
cycle;
– establishment and maintenance of the forge force for a desired forge time or forge distance or combination of
both, to complete the weldment.
Unclamping the work-holding devices may or may not be done automatically, thus completing the cycle of opera-
tions.
8 © ISO 2000 – All rights reserved

4.3.2 Features
Friction welding machines can be equipped with the following options:
– loading equipment;
– unloading equipment;
– turning units for facing, flash removal, machining;
– shearing unit to strip the flash;
– extended memory for welding programmes;
– weld identification unit;
– angular orientation;
– monitoring;
– identification;
– in process proof testing.
5 Quality requirements
5.1 General
The regulations and recommendations which govern other welding processes apply only in part to friction welding.
Emphasis should be placed on the avoidance of imperfections rather than on developing methods to find them. An
important prerequisite for ensuring weld quality is the uniformity and consistency of the component to be welded.
For this reason, adequate quality assurance measures shall be taken during the pre-welding, welding and post-
welding process operations.
5.2 Pre-welding conditions
5.2.1 Condition of raw materials
To ensure repeatable properties of friction welds which remain constant within a friction welding series the following
conditions should be maintained :
– chemical analysis;
– structure;
– strength and hardness;
– dimensional and geometrical tolerances;
– supply conditions of the materials to be joined.
5.2.2 Preparation of the components to be welded
Unless otherwise required by the design specification the following should be adhered to:
The end of each component shall be prepared so that the faying surface lies in a plane at right angles to the axis of
rotation, the end being cut square. This end can be tapered if required so that the area of the faying surface is
reduced for the early stage of the welding cycle. The length of the taper shall be not greater than 50 % of the burn-
off length for each component and sufficient to ensure that the plane of the weld interface is on the parallel portion
of the component, or at such a position as is indicated on the drawing agreed between the contracting parties.
Dirt, grease, rust and other surface oxides or protective films shall be removed from the faying surfaces before the
components are placed in the machine, except where surface contamination is shown to have no detrimental effect
on joint properties.
Surface irregularities on the faying surface, e.g. centre turning holes, shall only be allowed where they do not cause
harmful effects.
5.2.3 Component holding
The torque and axial forces resulting from the friction welding cycle are normally resisted by the tooling. The
clamping force shall be not so great as to deform or mark the components beyond acceptable levels.
Suitable backstops are used wherever possible to prevent axial slippage. Plugs may be used to provide additional
support when gripping hollow components.
The components to be welded shall be set in the machine so that their axes lie within the limits specified for
concentricity and alignment.
To achieve the required alignment it is sometimes necessary to machine or clean the surfaces of the components to
be clamped.
Particular care is necessary with regard to tooling and alignment when welding hollow sections having an outside
dimension that is large relative to the wall thickness of the component.
The overhang shall not be so short as to cause unacceptable chilling of the component or so long as to cause
unacceptable misalignment or vibration of the opposing faces during the friction and forge phases.
The two components should be clamped wherever possible so that the overhang of each is equal, unless the
difference in composition or size of the two components makes it desirable for them to have different overhangs,
either to achieve a heat balance or to permit effective work holding.
5.3 Post-welding treatment
Where necessary, further procedures as machining and/or post-weld heat treatment of friction welds shall be
carried out in accordance with the expected environmental operating conditions.
5.4 Quality assurance
The system of quality control employed shall take into consideration the following factors:
– production rate and batch size;
– size and design of weldments;
– economic considerations;
– intended operating conditions.
The system employed shall be sufficient to ensure that consistent and satisfactory weld quality is maintained on a
batch or individual basis.
NOTE: The system should ensure that procedures are in place to ensure regular calibration of the friction
welding machine.
Production quality control records shall be kept, the form and content of which shall be agreed between the
contracting parties.
Guidelines for the level of quality assurance to be used are given in Annex D.
Whether destructive or non-destructive testing methods can be applied depends on the special use of the welded
components. A list of destructive and non-destructive testing methods which are generally suitable for friction
welding is appended in Annex E. Possible testing procedures are given to facilitate the choice of the most
appropriate method.
10 © ISO 2000 – All rights reserved

6 Welding procedure specification (WPS)
6.1 General
The welding procedure specification (WPS) shall give details of how a welding operation is to be performed and
shall contain all relevant information about the welding work.
Welding procedure specifications may cover a certain range of cross sectional areas. Additionally some manufactu-
rers may prefer to prepare work instructions for each specific job as part of the detailed production planning.
Components used for WPS qualification purposes shall be representative of those used for actual production
components in the following respects:
– chemistry;
– faying surface condition;
– heat treatment;
– joint geometry/dimensions.
The information listed below is adequate for most welding operations. For some applications it may be necessary to
supplement or reduce the list. The relevant information shall be specified in the WPS.
Ranges and tolerances, according to the manufacturer's experience, shall be specified where appropriate.
An example of a recommended WPS-format is shown in Annex F.
6.2 Information related to the manufacturer
6.2.1 Identification of the manufacturer
– Unique identification.
6.2.2 Identification of the WPS
– Alphanumeric designation (reference code) related to a specific friction welding machine.
6.3 Information related to the material
6.3.1 Material type
– Identification of the material, preferably by reference to an appropriate standard.
A WPS may cover a group of materials, if agreed prior to production, see 7.1.
6.3.2 Component information
– Geometry;
– dimensions;
– chemical analysis;
– other relevant information.
6.4 Welding parameters
All relevant parameters shall be listed (see clause 4 and Annex F).
6.5 Joint
6.5.1 Joint design
A sketch of the joint design showing position of weld(s), details and tolerances may be made.
6.5.2 Preparation of components
Selected method of surface preparation, as necessary (e. g. sawing, turning).
6.5.3 Fixtures
– The methods to be used;
– details of fixtures and backstops.
6.6 Optional devices
E.g. flash forming, supports when welding thin-walled tubes.
7 Welding procedure approval
7.1 Principles
The following procedure is designed to meet high duty applications.
Welding procedure specifications for friction welding shall be approved prior to production whenever required. The
methods of approval are:
– approval by welding procedure test according to 7.2;
– approval based on previous experience according to 7.4.
This standard does not invalidate previous welding procedure approvals made to specifications providing the intent
of the technical requirements is satisfied and the previous procedure approvals are relevant to the application and
production work on which they are to be employed. Consideration of previous procedure approvals to former
national standards or specifications should be, at the time of enquiry or contract stage, agreed between the
contracting parties.
7.2 Welding procedure tests
7.2.1 Application
When procedure tests are required, tests shall be carried out in accordance with the provisions in this section
unless more severe tests are required by the design specification or by other standards when these shall apply.
7.2.2 Preliminary welding procedure specification (pWPS)
The preliminary welding procedure specification shall be prepared in accordance with clause 6 of the standard.
7.2.3 Number of test weldments
Unless more severe tests are required by the design specification or by other standards the minimum test require-
ments are as follows:
– a minimum of two weldments shall be produced for WPS qualification;
– a minimum of two weldments shall be evaluated.
12 © ISO 2000 – All rights reserved

If one of the test specimens has failed a defined acceptance criteria, then the welding conditions shall be redeter-
mined in order to satisfy the accepted criteria and further two tests specimens shall be evaluated.
7.2.4 Specification for test specimens
7.2.4.1 Solid sections - Specimens from bar to bar weldments for bend test
The weld shall be dressed flush, unless otherwise agreed by the test specification, having a surface finish that does
not affect the result. When components of differing sections are welded together, the larger section shall be
reduced to equal that of the smaller after welding.
Specimens shall be tested whole where possible or prepared as shown in figure 7.
Dimensions in millimetres
Guide values:
Thickness: nominal 10 mm
Width: 25 mm
�
Length: depending on the component
1 is the position of weld interface
2 is the test specimen for bending
Figure 7 - Preparation of specimens for bend testing joints between solid components
If it is necessary to subdivide the test specimens into small specimens, the width of the subdivided specimens shall
be not less than 25 mm. Where a specimen will result in testing less than one-third of the total area, further 10 mm
wide slices shall be cut and tested.
In the preparation of specimens, methods of cutting which significantly effect the metallurgical structure of the
specimen shall not be used.
Where bar sections are welded to plate or other components of insufficient thickness to allow a bend test specimen
to be prepared, an alternative test procedure shall be agreed between the contracting parties.
7.2.4.2 Hollow sections
7.2.4.2.1 Specimens from tube to tube weldments for bend test
The weld shall be dressed flush on the inside and outside surfaces of the specimen, unless otherwise agreed by the
test specification, having a surface finish that does not affect the test result.
Four specimens shall be taken at equal intervals round the weldment (see figure 8). In the preparation of
specimens, methods of cutting which significantly effect the metallurgical structure of the specimen shall not be
used. Each specimen shall consist of a parallel sided strip cut so that the weld is approximately central.
The minimum width of each specimen shall be as follows:
– for tubes of outside diameter less than 50 mm:
t + D/10
– for tubes of outside diameter equal to or greater than 50 mm:
t + D/20
where: t is the wall thickness in mm;
D is the outside diameter of the prepared tube in mm.
Dimensions in millimetres
1 is the position of weld
Figure 8 - Specimens for bend testing joints between hollow components and solid or plate components
7.2.4.2.2 Specimens from tube to bar weldments and tube to plate weldments for bend test
The weld shall be dressed flush on the inside and outside surfaces of the specimen having a surface finish that
does not affect the test result.
Four test segments shall be cut as shown in figure 8. The cut shall just penetrate beyond the weld and the heat
effected zone.
14 © ISO 2000 – All rights reserved

7.2.5 Test procedures
7.2.5.1 Bend test
Where the dimensions and materials of the test piece are such that a viable bend test cannot be achieved, an
alternative procedure has to be stipulated. Otherwise the requirements given below shall apply.
Specimens prepared shall be bent round a former of diameter suggested in table 2. The plane of the weld shall be
positioned at the apex of the bend. Where specimens have been prepared as in figure 7, the longer face shall be
placed against the former. When bend testing tubular weldments, the number of the test specimens and their
relationship to the wall thickness is given in table 3.
Table 2 - Suggested bend diameters for selected materials
Material
Diameter of former
– carbon steel (0,25 % C max.) 3 t to 4 t
– commercially pure aluminium
– copper
– titanium
– austenitic stainless steel
– carbon steel (over 0,25 % C) 4 t to 5 t
– low alloy steel
– brasses and bronzes
– Al Mn 1
– all other combinations (similar or dissimilar) By agreement between the contracting parties.
NOTE: t is the specimen thickness or wall thickness
Specimens prepared in accordance with figure 8 shall be tested by bending two specimens inwards and two
outwards. The first inwardly bent specimen shall be shortened if necessary to give clearance to itself and the
second inward bend. No former shall be used in this test. Bending shall be by light hammer blows at right-angles to
the specimen, in a test rig designed for the purpose.
Table 3 - Location of specimens for bend testing of tubular weldments
Thickness Tension surface
– up to and including 10 mm – 2 inwards and 2 outwards
– above 10 mm to 20 mm – 2 inwards and 2 outwards or all 4 side face
– above 20 mm – all 4 side face
NOTE: When making a bend test on a specimen from items from hardenable material a "knee joint effect"
will be obtained on both sides of the HAZ with extreme and unpredictable forces in the boundary area. The
specimen does not adapt to the diameter of the former. Therefore, post weld heat treatment to reduce HAZ-
hardness can be undertaken prior to performe the bend test. Although evaluation procedure may be
considered. Also consideration has to be given to surface hardened materials where the hardened area may
affect mechanical test results.
7.2.5.2 Alternative tests
Alternative tests may be used in certain instances.
Further examinations and tests see Annex E.
7.2.6 Acceptance criteria
Each bend test specimen shall be capable of being bent to the angle agreed on by the test specification, without
fracture, although slight tearing shall not be considered a cause for rejection.
NOTE: Details of weld imperfections are given in Annex G.
7.3 Welding procedure approval record (WPAR)
All relevant data from the welding of a component needed for approval of a welding procedure specification as well
as all results from the testing of the test weld shall be recorded in a welding procedure approval record (WPAR).
An example of a recommended WPAR format is shown in Annex H.
7.4 Previous experience
Approval by previous experience is given when it can be shown by authenticated data that the manufacturer's
established production welding procedures have been capable of consistently producing welds of acceptable quality
over a period of time.
7.5 Circumstances mandating requalification
A WPS shall remain qualified unless the following occurs:
– Modifications or repairs are made to the machine which affect its welding performance.
– Materials or material conditions, or both, change from those specified in the WPS.
– Preparation of faying surfaces changes from that specified on the WPS.
– Unexplained nonconformity with WPS-mandated quality assurance requirements occurs.
7.6 Machine-specific nature of a WPS
A WPS is developed for a specific welding machine, it shall not be used on another machine without requalification,
except otherwise agreed.
7.7 Requalification procedure requirements
Requalification procedure requirements are identical to the qualification procedure requirements.
8 Welding personnel
8.1 Friction welding machine operator
Friction welding machine operators shall receive appropriate practical training including safe operating practices.
8.2 Friction welding machine setter
The friction welding machine setter is the person who is competent to set up friction welding equipment according to
specified welding procedures.
He has the required knowledge and skill for carrying out the work for quality assurance in the field of friction
welding.
The required competence may be proved by sufficient experience, in-house training, or could be by record or
certificate of successful participation in a course for friction welders.
8.3 Welding coordination personnel (supervisor)
The manufacturer shall have available suitable welding coordination personnel in order to give the welding
personnel the necessary instructions and to perform and supervise the work carefully. The welding coordinator
personnel shall have knowledge and experience in the field of friction welding, behaviour of materials and quality
assurance. The persons responsible for quality work shall be sufficiently authorised to take all the necessary steps.
The duties, interrelations and limits of the spheres of responsibility of those persons should be well defined.
16 © ISO 2000 – All rights reserved

Annex A
(informative)
Relationship of welding parameters
A.1 Welding parameters for direct drive rotational friction welding
A.1.1 General
The friction welding cycle can be conveniently divided into three main phases (friction phase, stopping phase and
forge phase). Each should be operated in such a manner as to ensure that the desired joint properties are
achieved. Figure 2 illustrates rotational speed, force and axial shortening with time for friction welding.
A.1.2 Friction phase
The rotational speed(s) and friction force(s) should be applied so that upsetting, once established, occurs
continuously throughout the friction phase.
Friction force(s) and rotational speed(s) should be appropriate
...