PATON B.E. Modern trends toward increase in strength
and life of welded structures
The set of topical problems
associated with fabrication of high-efficiency welded structures, increase
in their strength and reliability and extension of their life is
presented. The importance of improvement of scientific approaches to
design of welded joints is shown. Consideration is given to issues related
to evaluation of performance of main and process pipelines and effect of
plastic deformation on fracture toughness of pipe steels. Results of
investigations aimed at development of methods for improvement of fatigue
resistance of welded joints and fatigue crack arresting are presented. The
demand for a wider application of high-strength steels is noted.
Capabilities of the acoustic emission and optical holography methods in
terms of using them for diagnostics of welded structures are considered. |  2 |
ALYOSHIN N.P. and GORNAYA S.P. New approach to the
technology of ultrasonic testing of coarse-grained materials
The paper describes the solution of the problem of construction of an acousto-solidification model of
coarse-grained materials, allowing for the features of structure
formation, geometrical and energy factors of ultrasonic waves attenuation.
Analytical dependencies were derived, a program was prepared and some
results of calculation of the passage and scattering of all types of US
waves are given. A conclusion is made on the need to take into account the
actual geometry and energy of the US beam for a correct interpretation of
the results of UT of the objects from materials of the above type | 8 |
GARF E.F. and NETREBSKY M.A. Assessment of the
strength and residual life of pipelines with erosion-corrosion damage
The urgency of the considered
problem for nuclear and thermal power generation industry, is noted. It is
shown that the codes now in force permit the pipeline wall thinning by 15
% of the design thickness, which, in a number of cases leads to a
significant lowering of the structure reliability and can cause fracture.
Introduction of a restriction not only on the wall thinning values, but
also on the main dimensions of the thinning zone, is substantiated.
| 13 |
HEROLD H. and WOYWODE N. Elimination of cracks in
steel structures using design-technological measures
Numerous open and closed cracks were
detected in thick-walled welded elements of span structures of a
metallurgical workshop made from increased-strength steel plates 11-45 mm
thick. Cracks were registered also in welds between shafts and drum bases
of a belt conveyer. Explanations of formation of this type of defects are
given. Design-technological measures are suggested for elimination of such
cracks.
| 19 |
GORYNIN I.V., ILJIN A.V., LEONOV V.P. and MALYSHEVSKY
V.A. Design-technological strength of welded joints of off-shore
structures
Problems of assurance of reliability
of off-shore engineering structures, which cover a wide range of spheres,
are considered. Optimum results are obtained at a constant allowance for a
real technology during the process of the structure fabrication.
Approaches are described for the selection of materials, a system of
safety factors, design of connections and recommendations for additional
technological procedures, justification of requirements to the quality of
welded joints, improvement of methods of assessment of a brittle strength
and a cyclic life.
| 26 |
DVORETSKY V.I. Evaluation of residual life of
load-carrying welded structures and extension of their service life
It is shown that service life of
welded structures can be extended using safety factors allowed for in
design of these structures and based on differences in their actual
operating time and assigned life time. The method is suggested to reveal
the above safety factors in order to estimate residual life of the
structures on the basis of main design parameters affecting it.
| 34 |
ZUBCHENKO A.S., VASILCHENKO G.S. and DRAGUNOV
Yu.G. Application of leak-before-break concept for provision of the
safety of WWER-1000 type reactors
A program of R&D on
substantiation of applicability of leak-before-break concept to nuclear
reactor piping has been outlined and fulfilled. J-R curves measured on
full-scale samples cut out of a welded pipe with the working cross-section
of 70 by 250 mm with through-thickness and semi-elliptical cracks in the
circumferential weld metal were compared with similar curves derived on
ST-1T compact samples. It is found that the parameters of plastic fracture
toughness measured on ST-1T samples are characterised by a higher level of
reliability compared to those of full-scale samples.
| 39 |
ZUBCHENKO A.S., KHARINA I.L., RUNOV A.E. and MAKHANEV
V.O. Corrosion-mechanical strength of welded piping of austenitic
steels of RBMK reactors
Corrosion-mechanical strength of
welded piping of nuclear reactors equipment of 08Kh18N10T austenitic steel
is considered. Numerous circular and axial crack-like defects were
detected, which initiate and propagate by the mechanism of
intercrystalline stress corrosion cracking. It is found that the main
factors which determine the incubation period and intensity of welded
joint damage are the level and nature of distribution of residual welding
and service stresses, presence of the zones of plastically deformed metal
and composition of the medium which is in contact with the inner surface
of the piping.
| 45 |
KRASOVSKY A.Ya. and ORYNYAK I.V. Assessment of
residual life of welds in pipings of the first loop of nuclear power
stations damaged by intercrystalline corrosion
Considered are the methodological
principles of comprehensive estimation of strength and residual life of
spatial piping systems containing cracks. The method suggested consists of
such components as global stressed-strained state of a piping allowing for
all affecting force factors, allowance for residual welding stresses,
calculation of stress intensity factors, prediction of stable forms of
development of fatigue cracks and intercrystalline corrosion, estimation
of actual residual life of a piping containing defects and prediction of
conditions causing leak to fracture. | 54 |
KRIVOSHEEV P.I. Problems regarding welded structures
of the "shelter" object at the chornobyl nuclear power station
Problems with structures in the
"Shelter" object at the Chornobyl Nuclear Power Station (ChNPS) are
outlined. The most important measures intended for implementation of the
strategy of stabilization of the "Shelter" object are indicated. They are
based on building of the new and reinforcement of existing metal
structures by making an extensive use of welding. The experience gained
will be applied for further work aimed at long-term stabilization of the
"Shelter" object.
| 62 |
KNYSH V.V. Determination of cyclic life of structure
elements in arresting fatigue cracks
Method of calculated determination
of a cyclic life of structure elements with propagating fatigue cracks at
their arresting by an artificially-induced field of residual compressive
stresses ahead of tips of these cracks has been developed on the basis of
approaches of fracture mechanics.
| 69 |
LOBANOV L.M., PIVTORAK V.A. and KUVSHINSKY
N.G. Diagnostics of structures of metallic and composite materials
using holography, electron speckle-interferometry and shearography
Results of application of methods of
holographic interferometry, electron speckle-interferometry and
shearography for nondestructive quality control and determination of
residual stresses in elements and members of the welded and
adhesion-bonded structures made of metallic and nonmetallic materials are
presented. To make diagnostics of structures, the compact holographic
schemes and devices have been designed and manufactured with the help of
which the local fields of displacements and deformations in the zones of
defects and relaxation of residual stresses are recorded. Examples of
diagnostics of aircraft and machine-building structures using the
holographic interferometry, electron speckle-interferometry and
shearography are given.
| 72 |
MAKHNENKO V.I. and MAKHNENKO O.V. Development of
calculation procedures for assessment of allowable defects in welded
joints of critical structures
Algorithms of assessment of
allowable defects in welded joints of the critical structures are
considered on the basis of a well-known concept "fitness-for-purpose",
developed by the International Institute of Welding and advanced
approaches of fracture mechanics of bodies with cracks. A significant role
of residual welding stresses, geometric peculiarities of welded joints,
mechanical heterogeneity, caused by the effect of a welding thermal cycle
and appropriate impurities in weld metal, is outlined.
| 79 |
PANASYUK V.V. and ANDREYKIV O.Ye. New approaches to
assessing the welded joints life
The calculation model for solving
the problems of welded joint life has been formulated. In the proposed
model a welded joint is considered as a heterogeneous (by the physical and
mechanical properties) deformed solid with a defect like faulty
fusion-crack that propagates under cyclic loading of a body. The equations
for estimating the fatigue crack growth rate were obtained on the basis of
the balance of heterogeneous joint material fatigue fracture energy and
reversive elastoplastic deformation of the process zone in the vicinity of
the defect tip. The fatigue crack propagation direction with respect to
initial defect plane was established from the condition that this
direction provides the maximum crack rate. The proposed model was applied
for assessing residual life of the butt and T-joints and a good
correlation between the calculational and experimental data was found.
| 87 |
PATON B.E. and NEDOSEKA A.Ya. New approach to
evaluation of the condition of welded structures
New approaches to evaluation of the
condition of welded structures in service are considered. Shown is the
need to apply the technology of structure diagnostic based on 100 %
control of materials and structures which makes it necessary to implement
a package of measures including use of special diagnostic systems and
equipment, procedures of their application and standards which regulate
this work.
| 92 |
PATON B.E. and TROITSKY V.A. Development of
non-destructive testing of critical metal structures
The paper presents some recent
developments in the field of non-destructive testing, promising directions
of NDT as a basis for technical diagnostics of metal structures which have
been in service for a long time, new technological capabilities in
computerisation of the NDT process. The role of Ukrainian Society of NDT
and Technical Diagnostics is shown.
| 95 |
PERELMUTER A.V. Wear and reliability of steel
structures
General principles of wear of steel
structures are considered. Possible decisions which may be made after
assessment of technical state of structures are indicated. Data on the
accident rate of basic load-carrying structures are given. It is noted
that in the majority of cases the accident rate is not related to the
safety factor. In-service monitoring of the technical state of an object
is considered to be very important. The necessity of developing regulatory
and methodological documents for specification, assessment and maintenance
of a certain level of safety of load-carrying structures is substantiated.
| 102 |
RAGUNOVICH S.P., TSYGANOV V.A. and SHELEG
V.K. Electric-arc welding under forced conditions
Described is the approach to
investigation of relationship between volt-ampere dynamic characteristics
of a heat source and peculiarities of formation of the weld pool which
determine the quality of welding. The concept of computer diagnostics and
monitoring of the arc welding process, based on the finite number of
statistical moments of the arc power, is presented. The quantitative
indication of the welded joint quality is suggested.
| 102 |
CERJAK H. and LETOFSKY E. Structure and properties of
E911 steel welded joints
Weldability and creep rupture
strength of a new low-carbon chromium steel of the ferritic class at
elevated temperatures were investigated. Compared to the known P91 steel,
the new steel is further alloyed with tungsten. Investigations
demonstrated that E911 steel is not inferior to P91 steel in weldability,
while the creep rupture values of E911 steel welded joint are higher than
those of P91 welded joint.
| 112 |
SMIRNOV V.V. and TSUKUROV O.A. Problems of
certification of welding fabrication in machine-building branches of
RUSSIA
The state-of-the-art in
certification of welding fabrication in the machine-building industry
branches of Russia is analyzed and evaluated. The ways of an integrated
solution of problems existing in the field of certification are suggested.
| 117 |
STEKLOV O.I. Mechanical-corrosion strength of welded
structures
State-of-the-art of the metal stock
of welded structures under the conditions of their corrosion and ageing is
considered. Specifics of a mechanical-corrosion strength of welded joints
and approaches to the calculation of strength at stress corrosion are
shown.
| 125 |
FROLOV K.V. and MAKHUTOV N.A. Strength and life of
welded joints in nuclear power reactor structures
Features of design, technological
solutions, welding defects and their influence on generation of the
stressed-strained states in load-carrying structures of water-water power
reactors are considered. Given are the results of experimental and design
analysis of the fields of stresses which induce various limit states
during the regular and emergency operation of NPP. Interaction of the
academic, research, design, technological organisations and branch
research institutes in solving the problems of strength and life of welded
joints, is shown.
| 132 |
FUJITA Yu. and YURIOKA N. Recent developments of steel
and welding materials capable of improving structural integrity
A number of problems associated with
the creation of high-reliability engineering structures is considered.
They include the peculiarities of application of structural materials of
the new generation which is characterized by a high strength, corrosion
resistance, high-temperature and heat resistance. The ways of development
of materials for their welding are defined. It is shown that a
simultaneous development of steels and welding consumables is a very
important link in the process of improvement of reliability of welded
joints from the point of view of resistance to tough and brittle fracture,
fatigue, corrosion and/or creep.
| 139 |
FUJITA Yu., MANABE Yu., ZENITANI S. and URAKAWA
S. Development of two wires tig welding with electromagnetically
controlled molten pool process
In horizontal position, welding bead
has an inclination to become hanging bead by gravity, and this problem
makes horizontal welding difficult for high-deposition rate welding. To
solve this problem, authors proposed a new concept of welding process,
so-called electromagnetically controlled molten pool (ECMP) welding
process. In this process the molten metal flow and bead shape are
controlled by using upward electromagnetic force.
| 145 |
VON HOFE D. and MIDDELDORF K. Innovations in joining
technology - processes and products for the future
Promising areas of development of
different materials (steels, light metals and alloys, metal foams,
composites, polymers) are considered. It is noted that in the future
welding and related technologies will be the preferred methods, because of
their high productivity, high degree of automation and simulation.
| 149 |
CZWORNOG B. Effect of shielding gas composition on
characteristics of high-efficiency consumable-electrode shielded-gas
welding (mag)
The results of investigation of
high-efficiency processes of welding in Ar-He-CO2 and
Ar-CO2 mixtures at 450 A currents are given. The sizes of a
cross-section of deposited beads, including the depth of penetration are
evaluated. The chemical composition was determined, metallographic
examinations, and also the tensile tests, impact bend and fracture
toughness tests of metal deposited in shielding gas mixtures at 300, 350
and 400 A currents were performed. There were no significant differences
in properties of the metal deposited in various mixtures. Good
characteristics of properties of the deposited metal and welded joints
obtained at currents up to 430 A using all compositions of shielding gas
mixtures were confirmed.
| 157 |
CHERNYAEV K.V. and VASIN E.S. Ensuring of safe
operation and extension of service life of main pipelines
The Joint-Stock Company Transneft
developed and put into operation the system for ensuring safe operation
and extension of service life of main pipelines. The system is based on
integrated four-level diagnostic monitoring using in-pipe high-resolution
diagnostic gears, allowing all types of defects which are the main causes
of accidents to be revealed. Repair of pipelines is planned on the basis
of estimation of an extent of danger of defects revealed. The
composite-coupling technology is employed for selective repair of
pipelines without any interruption of pumping. The system makes it
possible to fundamentally decrease the rate of accidents at main oil
pipelines and provides substantial cost effectiveness.
| 161 |
SHAN JIGUO, WU AIPING, ZHANG DI and REN JIALIE Heat
treatment and cladding using a light beam heating
The problems of heat treatment and
cladding using a method of a light beam heating to improve the
serviceability of components under the complex conditions of loading are
considered. It was established that the use of a light beam source is an
alternative to a laser source. It is shown that the light beam cladding of
a composite powder of Ni-Cr-B-Si-WC system on steel 45 contributes to the
increase in microhardness of coating almost by 2 times.
| 164 |
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| 167 |
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