PROCESSES OF ARC WELDING. METALLURGY. MARKETS

196 Pages·2013·4.14 MB·English

E.O. Paton Electric Welding Institute of the National Academy of Sciences of Ukraine
International Scientific-Technical and Production Journal
June–July / 2014
Nos. 6–7
Published since 2000
English translation of the monthly «Avtomaticheskaya Svarka» (Automatic Welding) journal published in Russian since 1948
Editor-in-Chief B.E.Paton
EDITORIAL BOARD
Yu.S. Borisov,
B.V. Khitrovskaya (exec. secretary),
V.F. Khorunov, V.V. Knysh, I.V. Krivtsun,
S.I. Kuchuk-Yatsenko (vice-chief editor),
Yu.N. Lankin, V.N. Lipodaev (vice-chief editor),
L.M. Lobanov, A.A. Mazur,
O.K. Nazarenko, I.K. Pokhodnya,
V.D. Poznyakov, I.A. Ryabtsev,
K.A. Yushchenko,
A.T. Zelnichenko (exec. director)
(Editorial Board Includes PWI Scientists)
INTERNATIONAL EDITORIAL
COUNCIL
N.P. Alyoshin
N.E. Bauman MSTU, Moscow, Russia
V.G. Fartushny
Welding Society of Ukraine, Kiev, Ukraine
Guan Qiao
Beijing Aeronautical Institute, China
V.I. Lysak
Volgograd State Technical University, Russia
B.E. Paton
PWI, Kiev, Ukraine
Ya. Pilarczyk
Weiding Institute, Gliwice, Poland
U. Reisgen
Welding and Joining Institute, Aachen, Germany
O.I. Steklov
Welding Society, Moscow, Russia
G.A. Turichin
St.-Petersburg State Polytechn. Univ., Russia
M. Zinigrad
College of Judea & Samaria, Ariel, Israel
A.S. Zubchenko
OKB «Gidropress», Podolsk, Russia
Founders
E.O. Paton Electric Welding Institute
of the NAS of Ukraine,
International Association «Welding»
Publisher
International Association «Welding»
Translators
A.A. Fomin, O.S. Kurochko,
I.N. Kutianova
Editor
N.A. Dmitrieva
Electron galley
D.I. Sereda, T.Yu. Snegiryova
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© PWI, International Association «Welding», 2014
CONTENTS
PROCESSES OF ARC WELDING. METALLURGY. MARKETS
Steklov O.I., Antonov A.A. and Sevostianov S.P. Ensuring integrity of welded structures and constructions
at their long-term service with application of renovation technologies ..................................................... 4
Yushchenko K.A., Savchenko V.S., Chervyakov N.O., Zvyagintseva A.V., Monko G.G. and Pestov V.A.
Investigation of cracking susceptibility of austenitic material using PVR-test procedure ........................... 10
Paton B.E., Rimsky S.T. and Galinich V.I. Application of shielding gases in welding production
(Review) ............................................................................................................................................... 14
Markashova L.I., Poznyakov V.D., Berdnikova E.N., Gajvoronsky A.A. and Alekseenko T.A. Effect of
structural factors on mechanical properties and crack resistance of welded joints of metals, alloys and
composite materials .............................................................................................................................. 22
Dmitrik V.V. and Bartash S.N. Peculiarities of degradation of metal of welded joints of steam pipelines of
heat power plants ................................................................................................................................. 29
Paltsevich A.P., Sinyuk V.S. and Ignatenko A.V. Interaction of hydrogen with deformed metal .................. 31
Markashova L.I., Kushnaryova O.S. and Alekseenko I.I. Effect of scandium-containing wire on structure
and properties of joints of aluminum-lithium alloys produced by argon-arc welding ................................. 35
Kononenko V.Ya. Underwater welding and cutting in CIS countries ......................................................... 40
Mazur A.A., Pustovojt S.V., Petruk V.S. and Brovchenko N.S. Market of welding consumables
in Ukraine ............................................................................................................................................. 46
CONSUMABLES FOR MECHANIZED METHODS OF WELDING
Shlepakov V.N. Physical-metallurgical and welding-technological properties of gas-shielded flux-cored
wires for welding of structural steels ...................................................................................................... 53
Rosert R. Application of flux-cored wires for welding in industry ............................................................. 57
Golovko V.V., Stepanyuk S.N. and Ermolenko D.Yu. Role of welding flux in formation of weld metal
during arc welding of high-strength low-alloy steels ............................................................................... 62
Zhudra A.P. Tungsten carbide based cladding materials ......................................................................... 66
Voronchuk A.P. Flux-cored strips for wear-resistant surfacing ................................................................ 72
Maksimov S.Yu., Machulyak V.V., Sheremeta A.V. and Goncharenko E.I. Investigation of influence of
microalloying with titanium and boron of weld metal on its mechanical properties in underwater
welding ................................................................................................................................................. 76
Ilyushenko V.M., Anoshin V.A., Majdanchuk T.B. and Lukianchenko E.P. Effectiveness of application of
new consumables in welding and surfacing of copper and its alloys (Review) .......................................... 80
Livshits I.M. Evaluation of suitability of welding wire of Sv-10GN1MA type produced by ESAB for
manufacturing NPP equipment .............................................................................................................. 84
Strelenko N.M., Zhdanov L.A. and Goncharov I.A. Flux for electric arc surfacing providing
high-temperature removal of slag coating .............................................................................................. 87
Zalevsky A.V., Galinich V.I., Goncharov I.A., Osipov N.Ya., Netyaga V.I. and Kirichenko O.P. New
capabilities of the oldest enterprise on production of welding fluxes ....................................................... 92
Kondratiev I.A. and Ryabtsev I.A. Flux-cored wires for surfacing of steel hot mill rolls .............................. 95
Kuskov Yu.M. Discrete filler materials for surfacing in current-conducting mould .................................... 97
Turyk E.V. Manufacturing defects in welding consumables influencing the quality of welded joints .......... 103
Solomka E.A., Lobanov A.I., Orlov L.N., Golyakevich A.A. and Khilko A.V. Restoration and strengthening
surfacing of parts of die equipment ...................................................................................................... 107
Elagin V.P. Selection of shielding gas for mechanized arc welding of dissimilar steels ............................ 110
Yushchenko K.A. and Yarovitsyn A.V. Influence of active gas content and disperse filler continuity on the
process of bead formation in microplasma powder surfacing of nickel superalloys ................................. 115
Royanov V.A. and Bobikov V.I. Application of pulse atomizing jet in electric arc metallizing ..................... 124
Pereplyotchikov E.F. Development of high-vanadium alloy for plasma-powder surfacing of knives for
cutting of non-metallic materials ........................................................................................................... 128
Kostin A.M., Butenko A.Yu. and Kvasnitsky V.V. Materials for strengthening of gas turbine blades .......... 132
CONSUMABLES FOR MANUAL ARC WELDING
Yushchenko K.A., Bulat A.V., Kakhovsky N.Yu., Samojlenko V.I., Maksimov S.Yu. and Grigorenko S.G.
Investigation of composition and structure of weld metal of Kh20N9G2B type made in wet underwater
welding ................................................................................................................................................ 135
Zakharov L.S., Gavrik A.R. and Lipodaev V.N. Electrodes for welding of dissimilar chromium martensitic
and chromium-nickel austenitic steels ................................................................................................... 139
Yushchenko K.A., Kakhovsky Yu.N., Bulat A.V., Morozova R.I., Zvyagintseva A.V., Samojlenko V.I. and
Olejnik Yu.V. Investigation of transition zone of low-carbon steel joint with high-alloyed Cr—Ni deposited
metal ................................................................................................................................................... 143
Vlasov A.F., Makarenko N.A. and Kushchy A.M. Heating and melting of electrodes with exothermic
mixture in coating ................................................................................................................................. 147
Levchenko O.G., Malakhov A.T. and Arlamov A.Yu. Ultraviolet radiation in manual arc welding using
covered electrodes .............................................................................................................................. 151
Gubenya I.P., Yavdoshchin I.R., Stepanyuk S.N. and Demetskaya A.V. Towards the problem of dispersity
and morphology of particles in welding aerosols ................................................................................... 155
Protsenko N.A. Status of normative base, certification and attestation of welding consumables
in Ukraine ............................................................................................................................................ 159
TECHNOLOGIES, EQUIPMENT AND CONTROL IN CONSUMABLES PRODUCTION
Marchenko A.E. Effect of charge grain composition on rheological characteristics on rheological
characteristics of compounds for low-hydrogen electrodes ................................................................... 163
Majdanchuk T.B. and Skorina N.V. Improvement of adaptability to fabrication and welding properties of
electrodes for tin bronze welding and surfacing .................................................................................... 172
Marchenko A.E. Thickness difference of electrode coatings caused by elastic turbulence of electrode
compounds under condition of nonisothermal pressure flow .................................................................. 177
Palievskaya E.A. and Sidlin Z.A. State of raw material base of electrode production ............................... 190
Gnatenko M.F., Voroshilo V.S. and Suchok A.D. Directions of improvement of equipment and
technology for electrode manufacture ................................................................................................... 194
ENSURING INTEGRITY OF WELDED STRUCTURES
AND CONSTRUCTIONS AT THEIR LONG-TERM SERVICE
WITH APPLICATION OF RENOVATION TECHNOLOGIES
O.I. STEKLOV1, A.A. ANTONOV1 and S.P. SEVOSTIANOV2
1I.M. Gubkin Russian State University of Oil and Gas
65 Leninsky Ave., 119991, Moscow, RF. E-mail: [email protected]
2Company «Gazprom VNIIGAZ»
PO 130, 115583, Moscow, RF. E-mail: [email protected]
Main pipelines in the Russian Federation have been in operation for a long time. Rate of failures in them
because of initiation of various corrosion and stress-corrosion defects has increased. Application of welding
repair technologies allows considerably lowering the risk of pipeline integrity violation. However, appli-
cation of welding technologies in repair of pipelines in long-term service requires allowing for additional
factors, which are not encountered in work performance on new pipelines. This and additional weldability
studies, as well as certain requirements to welding consumables and allowing for stressed state resulting
from application of renovation welding technologies, are described in this paper. 9 Ref., 8 Figures.
Keywords: main pipeline, repair technologies, wel- welding fabrication, alongside implementation of
dability, corrosion, stress corrosion cracking, require-
new projects, is maintaining the integrity of
ments to welding consumables, residual stresses, ultra-
welded structures after long-term service using
sonic impact treatment
renovation welding and related technologies in
Most of welded structures and constructions, order to prevent technogeneous and ecological
making up half of the country’s metal reserves catastrophies. Solution of this problem is consid-
and built in the pre-restructuring period, are at
ered in the case of main oil-and-gas pipelines.
the stage of ageing and failure rate increase be-
A characteristic regularity of failure rate in
cause of damage accumulation, which is due to
the case of analysis of technical condition of the
degradation processes in metals, fatigue, creep
entire system of main oil pipelines, conducted in
and corrosion.
1990s [1], is shown in Figure 1. Specific failure
Average age of oil-and-gas pipelines is more
rate index λ (1/1000 km⋅year), depending on
than 30 years and more than 70 % of tank fleet
operation life τ of the main pipelines, is charac-
have exhausted their specified service life.
terized by three periods:
Bridges, overpasses and other facilities are in a
I – debugging, period of early failures at
complicated state. A considerable part of housing
decreasing rate, when defficiencies of design,
and communal facilities require renovation.
construction and welding-assembly operations
Therefore, one of the important problems of
are revealed;
II – normal operation with failures, predomi-
nantly of random nature;
III – increase of failure rate, in connection
with degradation processes in the metal, protec-
tive coatings and corrosion.
Such a situation is characteristic also for main
gas pipelines, as well as other facilities of oil-
and-gas complex [2]. In connection with the
above-mentioned problems, an extremely urgent
issue now is that of monitoring and assessment
of the predicted life of constructions to determine
the admissible terms of service, repair and reno-
Figure 1. Dependence of specific failure rate index on service vation, prediction and assessment of technogene-
life of main oil pipelines (for I—III see the text) ous and economic risk. The basis of monitoring
is technical diagnostics «by the state».
© O.I. STEKLOV, A.A. ANTONOV and S.P. SEVOSTIANOV, 2014
4 6-7/2014
Specialized monitoring systems are developed first preliminary (express), and then also final
for various objects, allowing for the structure report on pipe defectiveness state.
features and service conditions. Second problem in development of the above
For gas-and-oil pipeline systems a complex situation in the object in service consists in that
three-level monitoring system is promising [3], when obtaining information about the defects
which includes: preventing normal (without pressure lowering)
• geotechnical diagnostics based on aerospace pipeline operation, repair operations on defective
monitoring data; section replacement cannot be performed because
• in-pipe diagnostics; of impossibility of bringing heavy construction
• ground-based instrumental diagnostics, pri- machinery to the site. In terms of location this
marily, of potentially hazardous pipeline sec- is mainly true for pipelines in marsh, flood-plain
tions, detected by the data of in-pipe and geotech- and water barrier crossing areas. Timewise, it
nical diagnostics. coincides with spring—summer period and
Such a comprehensive approach to evaluation autumn, up to marsh freezing and establishing
of gas pipeline technical state allowed improving of winter passageways along the route. Thus,
the effectiveness of planning diagnostic and re- starting from seasonal thawing of marshes
pair operations, as well as reliability of the entire through the entire summer period of operation
gas transportation system and somewhat lower- up to autumn—winter freezing of marshes and
ing accident rate [4]. creating ice crossings the operators are limited
Owing to improvement of methods of pipeline as to promptness of removing defects, preventing
condition diagnostics and evaluation using in- pipeline normal service.
pipe flaw detection, a large number of defects of The first problem can be partially solved by
corrosion and corrosion-mechanical origin are de- eliminating defects before pipeline taking out of
tected on pipeline outer surface. service for overhauling, through involving serv-
The most critical kind of defects are stress ice resources and performance of emergency-re-
corrosion cracks, i.e. stress corrosion cracking conditioning repair. Now the second problem is
(SCC) defects or their clusters (in the form of associated with an unsurmountable obstacle –
«crack field»), which have a predominantly lon- conditions, under which such inadmissible de-
gitudinal orientation and are located both in base fects as SC cracks cannot be eliminated by widely
metal and in the zone of shop longitudinal welds. accepted technologies. The more so, since in the
This kind of defects are responsible for up to majority of normative documents such defects
70 % of emergency failures of main gas pipelines. are unrepairable, and are eliminated by the only
Currently available normative documents method of cutting-out the defective section and
specify the dimensions of admissible defects, de- mounting, welding-in of a new pipe.
termining their rejection level. SC cracks, the Special repair technologies play a particular
depth of which goes beyond negative tolerance role under these conditions for the operators.
for pipe wall thickness, were qualified as inad- These technologies, without cutting-out the de-
missible defects, which must be removed (cut- fective section and, hence, without involving a
ting-out pipe defective section). Calculation of large complex of heavy construction machinery,
safe pressure can be an alternative, at which the allow performance of repair, restoring pipeline
defective pipeline can fulfill its function without operability. Figure 2 gives the classification of
failure, but with productivity loss during product these technologies. Such technologies include ap-
pumping. It should be noted that in such a situ- plication of reinforcing elements (sleeves) (Fi-
ation the operators face several problems. gure 3) and repair welding (building-up) of all
The first is to establish the actual technical kinds of defects, including such hazardous defects
state before assigning the overhauling status to as SCC [5].
the object, with complete or partial replacement Application of technology of defect repair by
of defective elements, sections, pipes, etc. At this welding (building-up) after obtaining informa-
stage either the project or most of the kinds of tion about inadmissible hazardous defect, pre-
resources for repair operations performance are venting normal operation, will allow operators
still absent. This stage is characterized by that ensuring its elimination by repair operations, also
the object still cannot be taken out of service for in difficult-of-access marshy areas. Another ad-
overhauling, but operative data about its tech- vantage provided by such technologies is the abil-
nical state have already been obtained. This pe- ity to restore the pipe without its replacement.
riod, as a rule, is associated with completion of Application of repair welding (building-up)
in-pipe examination of the pipeline and obtaining technologies for structures after long-term serv-
6-7/2014 5
Figure 2. Welding technologies for gas pipeline in-service repair
Figure 3. Schematics of repair by welded sleeves of defects in pipes and welds of sections of main gas pipeline linear
part: a, b – unsealed reinforcing sleeves; c—g – sealed reinforcing sleeves and sleeve assemblies; 1 – sealant; 2 –
composite; 3 – temporary sleeve
6 6-7/2014
ice raises a number of key issues: evaluation of fied strength characteristics of the deposited met-
material weldability after long-term service; sub- al and its «cathodicity» relative to base metal.
stantiated selection of welding (filler) consu- Proceeding from design strength of the object
mables; optimization of technological process and allowing for good weldability, it is rational
of welding (building-up); substantiation of ap- to ensure strength characteristics from the con-
plication of additional postweld related tech- dition of σw, σw ≤ σm, σm (where «w» and «m»
t y t y
nologies.
indices are the welded joint and base metal, re-
Summing up, the following can be noted.
spectively).
In long-term service of equipment, an essential
To ensure resistance to electrochemical corro-
lowering of weldability of metal being repaired
sion, the following condition should be fulfilled:
is possible, in connection with degradation proc-
ϕw ≥ ϕm (where ϕw, ϕm are the electrode poten-
esses in the metal as a result of strain ageing,
tials of welded (built-up) and base metal, respec-
saturation with active reagents from natural and
technogeneous media, that requires analysis al- tively).
lowing for the conditions and term of service. Technology of repair-reconditioning operations
Particularly important is evaluation of material is determined, allowing for the above principles,
weldability under service conditions at the im- in particular without hydrocarbons bleeding [6].
pact of hydrogen-evolving and hydrogen-produc- We will single out only the first group –
ing media and for structures operating at elevated welding (building-up) of outer part-through de-
temperatures under creep conditions. Unfortu- fects of pipes, including product-induced SCC
nately, no systemic studies on this problem have defects, from the general classification of welding
been performed so far. technologies in gas pipeline repair (see Figure 2).
Selection of filler materials, allowing for the Criteria for application of this kind of repair are
impact of active media, should ensure the speci- as follows:
Figure 4. Sequence of technological operations of repair by welding (building-up) of part-thickness outer defects in pipe
metal: a – appearance of pipe with defective section; b – transverse section of pipe along A—A line with defective area,
respectively; c – transverse section of pipe along A—A line after mechanical cutting-out of defective layer; d – transverse
section of pipe along B—B line after mechanical cutting-out of defective layer; e – pipe appearance after repair; f –
transverse section of pipe along A—A line after repair; g – transverse section of pipe along B—B line after mechanical
scraping of facing layer
6-7/2014 7
Figure 7. Characteristic diagram of residual stress distribu-
tion in the circumferential direction after repair by build-
ing-up: solid curves – longitudinal stresses; hatched –
Figure 5. Dividing extended repair section into separate circumferential
zones 1—4, and sequence of filling them with deposited metal
σ ≤ σ — σ .
using welding technologies res th work
Allowing for safety factor σ ≈ 0.5σ , and
• ensuring temperature-plastic stability of work y
σ value is equal to approximately 0.76σ based
molten and heated metal in the zone of heat th y
on generalization of failure rate statistics [7].
source impact (arc, plasma), proceeding from the
Admissible value of σ ≤ (0.2—0.3)σ .
conditions of «not burning through» and preser- res y
An important condition of this technology is
vation of strength in the localized heat zone;
welding with a controllable thermal cycle, with
• admissible deformability of pipe body in
heat input and current, minimum admissible in
welding (building-up) zone under the impact of
terms of process stability:
inherent stress-strain state in thermodeforma-
tional welding cycle, proceeding from the con- q/V → min, I → min.
w
dition of strength of a pipeline with geometry
For example, in practice for manual arc weld-
defects;
ing with 2.6—3.2 mm consumable electrodes it
• admissible level of inherent residual welding
corresponds to I = 90—120 A. Schematics of
stresses in building-up zone. w
repair technologies are given in Figure 4.
For gas pipeline admissible value of residual
In welding-up of extended defects, in order
welding stresses in building-up zone is deter-
to reduce pipe body deformation, caused by ther-
mined from the condition of prevention of SCC,
modeformational cycle of welding, building-up
arising at total working σ and residual σ
work res
zone should be divided into smaller sections with
stresses exceeding threshold (critical) σ σ +
th work
reverse-successive direction of welding (build-
+ σ ≤ σ . Hence,
res th
ing-up) (Figure 5).
A procedure and portable equipment have
been developed in order to determine the level
and distribution of σ in building-up zone. The
res
procedure is based on application of nondestruc-
tive methods of express-diagnostics of stress-
strain state (for instance, equipment based on
Barkhausen noise method) at the first stage, al-
lowing detection of the areas of examined section
with maximum values of residual stresses. More
Figure 6. Characteristic diagram of residual stress distribu-
tion in the axial direction after repair building-up: 1 – Figure 8. Characteristic field of residual stresses after pipe
longitudinal; 2 – circumferential stress deposition
8 6-7/2014
precise determination of residual stress value in 3. When selecting welding consumables, at-
the detected areas is performed using the method tention should be given to ensuring the specified
of drilling a blind hole with recording of dis- strength characteristics and cathodicity relative
placement by speckle-interferometer, in keeping to base metal.
with GOST R 52891—2007. Integrated applica- 4. Admissible residual stresses after perform-
tion of several methods, fundamentally different ance of repair building-up should not exceed 20—
by their operating principles, allows increasing 30 % of yield point.
final result validity. Investigations revealed that 5. Residual stress fields, developing after re-
residual stress fields after repair building-up have pair building-up performance, have a common
a characteristic pattern of distribution in the ax- characteristic shape, irrespective of deposition se-
ial and circumferential directions, independent quence or direction of beads. The highest value
on building-up technology [8] (Figures 6 and 7). of tensile stresses develops in the base metal near
Thus, after any repair building-up, a field of building-up zone along pipe axis.
residual stresses, shown in Figure 8, develops in 6. Application of local methods of postweld
the main pipe. impact on residual stress fields allows lowering
In order to fulfill the specified conditions, stress-strain state level in the impact zone, in the
recommendations on the technology of postweld built-up section and in base metal regions adja-
treatment of building-up zone have been devel- cent to building-up zone.
oped. A fundamental point is localized lowering
of residual welding stresses in the zone of their
1. Chernyaev, V.D., Chernyaev, K.V., Berezin, V.L. et
maximum values. Classical thermal methods of
al. (1997) System reliability of main transport of hy-
lowering the level of residual stresses are not drocarbons. Ed. by V.D. Chernyaev. Moscow: Nedra.
2. Varlamov, V.L., Kanajkin, V.A., Matvienko, A.F. et
always applicable, that is related both to com-
al. (2012) Monitoring of defects and prediction of
plexity of organizing heating only in the local state of Russian main gas pipelines. Ekaterinburg:
deposit area, and to ineffectiveness of such a UNPTs.
3. Steklov, O.I. (2006) Complex technical diagnostics
method in terms of cost.
of main gas-and-oil pipelines. Territoriya Neft i Gaz,
In recommendations on postweld treatment, 4, 20—23; 5, 12—17; 6, 48—55.
a considerable place is taken up by technologies 4. Varlamov, D.P., Dedeshko, V.N., Kanajkin, V.A. et
al. (2012) Improvement of reliability of main gas
of local impact on individual zones in the deposit
pipelines by using repeated in-pipe flaw detection.
area, having peak values of tensile residual The Paton Welding J., 3, 20—25.
5. Vyshemirsky, E.M., Shipilov, A.V., Bespalov, B.I. et
stresses. Lowering of such peak values involves
al. (2006) New welding and repair technologies in
general redistribution of residual stress field, be- construction and repair of gas pipelines. Nauka i
cause of their mutual balance. A promising ap- Tekhnika v Gaz. Promyshlennosti, 2, 27—34.
6. Steklov, O.I., Shafikov, R.R., Sevostianov, S.P.
proach is lowering peak values, ensuring total
(2009) Theoretical-experimental substantiation of
favourable redistribution of residual stresses, by possibility of main pipeline repair using welding tech-
the method of ultrasonic peening treatment [9]. nologies without interrupting of gas pumping. Sva-
rochn. Proizvodstvo, 7, 12—17.
7. Steklov, O.I., Varlamov, V.P. (2012) Assessment of
Conclusions
threshold stress level of corrosion cracking in system
of main pipelines. Truboprovod. Transport (Teoriya i
1. Application of special welding technologies
Praktika), 3, 4—9.
allows extension of active service life of main 8. Antonov, A.A., Steklov, O.I., Antonov, A.A. (Jr) et
pipelines. al. (2010) Investigation of technological residual
stresses in welded joints of main pipelines. Zagot.
2. When preparing for application of welding Proizvodstvo v Mashinostroenii, 3, 13—19.
technologies in main pipelines after long-term 9. Antonov, A.A., Letunovsky, A.P. (2012) Reduction
of residual welded stresses by ultrasonic peening
service, it is necessary to perform additional
method. Truboprovod. Transport (Teoriya i Prak-
weldability studies. tika), 2, 21—26.
6-7/2014 9
INVESTIGATION OF СRACKING SUSCEPTIBILITY
OF AUSTENITIC MATERIAL
USING PVR-TEST PROCEDURE
K.A. YUSHCHENKO, V.S. SAVCHENKO, N.O. CHERVYAKOV,
A.V. ZVYAGINTSEVA, G.G. MONKO and V.A. PESTOV
E.O. Paton Electric Welding Institute, NASU
11 Bozhenko Str., 03680, Kiev, Ukraine. E-mail: [email protected]
Comparative investigation of hot cracking sensitivity of commercial welding wires has been performed. It
is shown that an all-purpose method of weldability evaluation can be the machine method with controllable
forced deformation during TIG welding (PVR-test method), which allows separating the conditions of
initiation of solidification cracks and ductility dip cracks in the weld and HAZ metal, and provides
comprehensive information about quantitative characteristics of cracking sensitivity. 6 Ref., 9 Figures.
Keywords: weldability, hot cracks, crack resistance According to international standard ISO
evaluation, high-alloyed steels, nickel alloys
17641-1:2004 hot cracks are violations of material
integrity, formed at high temperature along grain
Austenitic high-alloyed steels and their welded
boundaries (dendrite boundaries), when defor-
joints are rather sensitive to hot cracking. Their
mation or strain rate exceed a certain level. In
sensitivity is abruptly increased in fusion welding
their turn, cracks are subdivided into solidifica-
of stably austenitic steels and nickel alloys,
tion, liquation and ductility dip cracks [1].
which preserve face-centered cubic lattice in the
Causes for cracking are numerous, but usually
entire temperature range. Considering the com-
they initiate, when local ductility is insufficient
plexity of thermodeformational processes, taking
to counteract the developing welding deforma-
place in fusion welding of the above materials
tions. Exact mechanism of hot crack initiation
and diversity of the kinds of initiating cracks,
has not yet been clarified.
evaluation of material sensitivity to cracking and
Temperature interval of solidification crack
their classification are an urgent problem. Valu-
initiation (BTR) depends on the range of the
able information about hot cracking sensitivity
metal solid-liquid state at weld solidification.
can only be obtained in the case, when practically
Lower boundary of this range is determined by
all the crack types are studied in one sample
the value of solidus temperature T when solidi-
during one experiment. S
fication is over. Temperature range of ductility
In this case external influence during sample
dip (DTR) is determined by approximate ratio
realization is the same for all the zones of the
of (0.6—0.8)T (Figure 1). In this temperature
studied sample, however, having different for- S
mation mechanisms, different kinds of cracks de-
velop non-simultaneously, thus determining the
priorities at evaluation of crack resistance of the
joint as a whole.
Figure 1. Hot cracking in welded joints of high-alloyed Figure 2. Testing schematic at application of PVR-test
steels and alloys: R – recrystallization [2] method [6]
© K.A. YUSHCHENKO, V.S. SAVCHENKO, N.O. CHERVYAKOV, A.V. ZVYAGINTSEVA, G.G. MONKO and V.A. PESTOV, 2014
10 6-7/2014