On the basis of the data obtained, the following conclusions may be drawn. As the result of the Combined action of the thermal hold at the nitriding temperature and of impregnation of the metal with high-purity hydrogen, the crack propagation rate increases. These factors may also be the reason for the reduction in fatigue resistance in bending of the teeth of nitrided gears of high-purity metal. After the vacuum-arc remelting of 36Kh2N2MFA steel the fatigue resistance in bending of teeth heat-treated to KP 95-105 is 37% higher than in teeth of KP 65-70 electric-arc-melted steel, which is used at present for large gears. LITERATURE CITED I. 2. 3.

L . P . Gulyaev, Clean Steel [in Russian], Metallurgiya, Moscow (1975). A . N . Morozov, Hydrogen and Nitrogen in Steel [in Russian], Metallurgiya, Moscow (1968). M . O . Levitskii, Information Letter No. 37 of the Physicomechanical Institute of the Academy of Sciences of the Ukrainian S S R [ i n Russian], Naukova Dumka, Kiev (1974).

DESIGN AND TECHNOLOGICAL METHODS OF INCREASING THE LOW-CYCLE FATIGUE LIFE OF WELDED STRUCTURES V. I. Kovalenko, V. P. Rudenko, K. B. Katsov, O. G. Sokolov, and L. V. Grishchenko

UDC 621.791:620.178.3

In recent years in machine building there has been a tendency toward increasing the capacity Of units, mechanisms, and machines. In some cases the dimensions of individual design elements reach tens of meters and their weight tens and hundred of tons, which makes one-piece construction of them practically impossible. Therefore, for designers and engineers there arise complex problems of the creation of large parts and structures by the joining of rolled, forged, and cast elements by welding which would provide equal strength of the joint and the base material under static, impact, and especially cyclic loads. The majority of welded structures, in particular such equipment as floating drilling units, operate as a rule in contact with aggressive working media, primarily corrosive. As the result of the electrochemical nonuniformity of the weld joints, the influence of the corrosive medium on the life of the weld joints is especially significant [i, 2]. Electrochemical inhomogeneity together with physical and mechanical appearance are integral characteristics of the properties of weld joints. In turn, they are determined by [i]: i. Structural and Chemical Macro- and Microinhomogeneity of the Metal. The macroinhomogeneity is related to the presence of t h e c a s t metal of the joint, the heat-affected zone with a series of transition structures, and the base metal not subjected to the action of welding while the microinhomogeneity is caused by the presence of grains, grain boundaries, phases, inclusions, etc. within the limits of each zone of the weld joint. 2. Inhomogeneity in the elastoplastic stressed condition caused by nonuniform distribution of the residual deformations in the weld joint and also by stress and deformation concentration from the external load as the result of geometric nonuniformity of the weld joint. 3. Geometric nonuniformity related to the presence of: a) external factors of the joint form (poor penetration, undercuts, reinforcements, cold laps, cracks, etc.); b) internal defects (cracks, voids, etc.); c) design stress raisers, which are dependent upon the configuration and type of the weld joint (butt, T-joint, lap, etc.). In fundamental works devoted to the fatigue of weld joints, consideration is given primarily to questions of normal, multicycle fatigue [3-6], while many structures operate under conditions of significant low-frequency loads, that is, under low-cycle loading.

" G ] V. Karpenko Physicomechanical Institute, Academy of Sciences of the Ukrainian SSR, Lvov. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 18, No. i, pp. 92-100, January-February, 1982. Original article submitted October 8, 1980.

0038-5565/82/1801- 0083507.50

9 1982 Plenum Publishing Corporation

83

TABLE 1

Kcf [41

Type of weld joint

[41

[

1161

I

1,1--1,8

1,32 1,40 1,55

Butt

Butt joining of shapes Joining of stiffening ribs Lap with a shoulde?on the contour Lap with longitudinal fillet welds

1,7--2,6

1,69 2,33

2,0--2,2

1,4--2A '2,2--2,4 2,2--3,0 3.0--3.6 3,2--5,0

750 ~-.--o., ~- 700 ~ ~ "

650. L

I 25

Fig. i. Relationship of the strength of Yu3 steel in static tension of t = 20-mmthick samples to the depth of facing.

.L RSO

~.~,~

I--

j .

9

"

"

.

.

,,

.

,

__~

b

|. V////////~

}'////////A ~ i tf

Fig. 2. Sample for investigating the influence of facing geometry on the low-cycle fatigue of plate steel.

Fig. 3. Location of the fracture in low-cycle fatigue of Yu3 steel in a corrosive medium in relation to the length of facing, a) ~f/l < I; b) Zfll > i. Laboratory tests of small weld samples are insufficient for judging the low-cycle fatigue resistance of iarge full-scale weld joints since simulation of the latter presents known difficulties in metallurgical, technological, design, structural, and other respects. As a result for reliable evaluation of the supporting capacity of weld joints, experimental investigations must be made under conditions and on samples as close as possible to actual. To evaluate the life of heavy plate welded structures, the weight of the metal fused by welding in the production of which is counted in tens of tons, it is most suitable, as follows from the above, to make low-cycle fatigue tests by bending O f the elements of full-scale structures in the working media. At the same time, it is:necessary to take into consideration certain differences in the influence of the test conditions in an area of the sea, in

84

~,

~

"---,~_ .,3 .I..~~

0

/~

5O

Zf/Z

%

Fig. 4. Relationship of the life of Yu3 steel in a corrosive medium (R = --i, 2e a = 0.45%) to the length of facing: i) B/t = 5, h/t = 0.25; 2) B/t = 5, h/t = 0.50; 3) B/t = 5, h/t = 0.75; 4) B/t = 20, h/t = 0.50; 5) B/t = 20, h/t = 0.75.

3O

/

0

I

I

I

25

50

75

100

h/e,7. F i g . 5. I n f l u e n c e of the d e p t h o f f a c i n g and s h o t p e e n i n g on t h e l o w - c y c l e f a t i g u e o f Yu3 s t e e l i n a c o r r o s i v e medium (R = - - 1 , 2E a = o.45z): 1) S / t = 5, ~ f / ~ = 0 . 6 , p e e n i n g from b o t h s i d e s ; 2) the same but with peening from the side opposite the facing; 3) the same but without peening; 4) B/t = 20, ?~f/l = 0.56, without peening. /

~0 o

~'z0 0~ ~0 ~0

i 200

i

30o

I,,,

~in.A

Fig. 6. Relationship of the type of facing material and the facing parameters to the life of butt weld joints of type 1 8 K h N ~ steel in a corrosive medium (R = 0, E a = 0.45%): i) 07Kh3MD finishing; 2) finishing without facing; 3) EP-704 finishing.

85

~0

60

30

a

b

Fig. 7. Samples for investigating the influence of electrlc-arc finishing of weld joints on low-cycle fatigue (length of the working portion 300 mm).

80

2 ,/ 3.0 _ / ;

2.0 " 200

'

o

~ I

2.50

I

300 If m , A

I

3#0

Fig. 8. Influence of the finishing parameters a n d material on the low-cycle fatigue of T-shaped weld joints of type 18KhNMA steel in a corrosive medium (R = 0, ea = 0.45%): I) welding with EP-704 wire, finishing with EP647; 2) welding with EP704, finishing with ~I-981; 3) welding wlth ~P-704 without finishing; 4) welding with austenitic electrodes, finishing with ~P647; 5) welding with ~P-647 in carbon dioxide, finishing with 2P-647. seawater supplied to a laboratory, and in a medium simulating it on the llfe of the elements of floating drilling equipment. In short-term corrosion tests the water in the open sea is much more corrosive than its model and yields to it under laboratory conditions. With an increase in test time the difference in steel corrosion intensity in the different media decreases. The specific conditions of marine corrosion causing more nonuniform and deeper damage of the steel surface than in exposure in seawater in the laboratory cause lower low-cycle fatigue life of samples held in the sea than of those exposed in the laboratory. In the case of short low-cycle fatigue tests, the life of steel in seawater and in media ~mltating it is practically the same. In long experiments resulting from the low loading frequency, there is a tendency toward a reduction in the life of the steel in the more corrosive medium (3.5% NaCI solution) in comparison with the life in laboratory seawater. In this investigation the life of weld joints was evaluated on elements of full-size structures in air and in a synthetic model of seawater (3.5% NaCI solution).

86

The experiments were made on 20-mm-thick types 18KhNMA and Yu3 steels. The low-cycle fatigue tests were made on IP-20 [7] and IP-100 [8, 9] machines specially built for these purposes by bending using a rigid loading method with a frequency of 0.17 Hz. In the operation of welded structures, an asymmetric cycle is most characteristic while in a symmetric loading cycle the structure is under the most unfavorable conditions and the action of the factors having a negative influence on the fatigue strength is a maximum. As a result the tests were made using both symmetric (R = --i) and starting-from-zero (R = 0) cycles. The cycle amplitude was specified by the value of the relative deformation of the sample surface measured with the use of resistance strain gauges and the method described earlier [i0]o For all of the samples of this investigation, the range of the total relative deformation As was 0.45%. During the tests the moment of origin of a visible macrocrack and the total life until failure were recorded. The test samples were cut from full-size plates and prepared for welding or facing. The working surface of the plates was "black," that is, it was not given any finishing operation after rolling. Design and technological methods were used to increase the fatigue resistance of the welded structures. It is known [4, 6, 10-12] that the main reason for a sharp reduction in the fatigue strength of weld joints is external stress concentration. In many cases this is still true even in the presence of quite substantial internal defects in the metal of the weld. In analyzing fatigue failures of weld joints in connection with stress concentration the theoretical stress concentration factor ~ determined in the elastic area by theoretical calculations, on transparent models, by strain measurement, etc. is used [4]. In loading in the elastoplastic area the value of the stress concentration factor Ko decreases as the result of significant local plastic deformations. In investigating the low-cycle fatigue of weld joints, the stress concentration factor Ks, which is normally established by strain measurement, is used. In the elastic area ~ = K o = Ks, and in the elastoplastic K o < ~o < K s. Therefore, strength calculations of weld joints using ~ m a y lead to a reduction in effective deformations. Determination of K o in weld joints [IX] in the elastoplastic area by strain measurement is possible in the presence of load curves of the tested material with a similar plan of stressed condition but this is difficult to accomplish as a result of the difference in the properties of the weld joint zones. In the majority of cases in low-cycle fatigue calculations, the Stowell K s = (~o~-l)/(K~--l) and Neuber Ko.Ks/~ ~ = 1 equations are used [13, 14] to find K O and K s from known values of ~o" For multicycle fatigue of weld joints there is also the understanding of the effective stress intensity factor [4] Kef(a ) = O-lbase met./O-lweld.. In the case of low-cycle loading it is proposed to use the following conditional equation [15]: Kef(s) = Nbase met./Nweld.. In connection with the determining significance for the fatigue strength of weld joints of the geometric stress concentration, design methods of reducing it include rational design of welded structures [3, 4, 6, ii] and investigation of forms creating the minimum stress concentrationo Machining of joints with a milling cutter, a cutting tool, or an abrasive wheel, which provides a smooth junction between the joint and the base metal~ promotes a decrease in stress concentration in the joints and thereby an increase in their fatigue resistance. Especially effective is machining of butt joints, the fatigue limit of which after machining of the joint increases by 40-60% and in some cases reaches the level of the fatigue limit of the base metal [6]. With careful butt welding and grinding of the joint surface flush with the surface of the joined parts, the specifications of the American Welding Society for the design of bridges permit acceptance of the strength of such a joint as equal to 100% of the strength of the parts joined [5]. In welded structures it is necessary to avoid elements causing significant stress concentration and unfavorable residual stress distribution. Weld joints must not be located in areas of the structure with increased stress concentration. Wider use is recommended of butt weld joints, which are characterized by minimum stress concentration and have the highest fatigue strength (Table i~. The use of artificial stress concentration relievers in the form of chamfers and holes in the zones of weld joints with an increased stress concentration (near the start and finish

87

of the jolnt) makes it possible in some cases to increase their fatigue strength. The creation of compressive stresses in the zone of the joint by prestressing and other design measures [6] provides a positive effect [3]. Recently, the method of restoration of the operating life of parts and elements of structures by facing on worn or corrosion damaged areas of the metal by welding [17, 18] in place of the traditional replacement of parts or cutting out the damaged areas and welding on new plates has found use. For butt welded plates according to the results of low-cycle fatigue test results in a corrosive medium Kef(~ ) is 2.6-3.9 depending upon the type of electrode used in the welding (austenitic or low alloy, respectively). The coefficient Kef(e ) for plates with "stack" type facing with the same electrodes with production reinforcement of 2-3 mm is 1.4-1.8. Finishing of the facing flush with the base metal with removal of undercuts in the zone of fusion reduces Kef(t ) to 1.38. In facing heavy-plate structures the last passes must be made parallel to the direction of action of the maximum tensile stresses since if the passes are made transverse to it failure occurs in the facing, life is reduced by 30-50%, and the effect from its use instead of butt welding on of new elements is lost as the result of increased stress concentration. This new design method of increasing the low-cycle fatigue life is recommended as a repair method for structures damaged by pitting corrosion. However, for rational use of this effective method in practice thorough investigations for the purpose of creating the optimum technology for both the facing itself and for finishing of the faced areas are necessary. Investigations were made of the influence of facing geometry ~n the low-cycle fatigue of heavy-plate Yu3 steel. The facing was done with 3-mm-dlameter EA-IF2 electrodes under medium conditions. The presence of an area of facing on 20-mm-thlck flat tensile samples finished with an abrasive wheel flush w l t h t h e base metal caused practically no reduction in tensile strength (Fig. 11 all the way to a depth of taking the sample h/t equal to 50% of the sample thickness. With a further increase in the depth of taking the sample, the tensile strength drops, but the maximum change in it does not exceed 10%. Low-cycle fatigue tests of heavy-plate samples (Fig. 2) by bending are more sensitive to the presence of facing. It has been established that the facing geometry has a significant influence on the life of heavy-plate samples. Samples with a facing with a shorter working portion fall along the line of fusion (Fig. 3a). With an increase in the depth of taking the sample, the llfe drops (Fig. 4). Samples with a facing of the greater length of the working portion fail in the facing (Fig. 3b) and the number of cycles until failure is at the level of llfe of the base metal at any depth of taking the sample (Fig. 5). Consequently, in repairing structures facing must be done so that the line of fusion is at a distance from constructional stress raisers. In this case the llfe of the faced portions will be not less than the llfe of the base metal. The influence of facing geometry is qualitatively similar in tests both of samples of medium dimensions and of large ones. Failure of large samples with a small number of cycles may be explained by the action of the scale factor. Earlier it was established [15] that in low-cycle fatigue tests by bending of plate samples with a "black" surface of the same thickness t with different widths of the working portion b an increase in b/t above 3-5 leads to a reduction in life in air and in a corrosive medium. In our case with the same thickness (20 mm) and ratio of b/t = 5 for medium-size samples and b/t = 20 for large ones, the life of the latter was 40-50% less. On the other hand, the life of a weld joint drops with an increase both in thickness and in the width of a butt welded plate [19]. One of the deciding factors causing a substantial reduction in the fatigue strength of butt welded joints with an increase in their cross section is, in the opinion of the author of [19], the increase in residual welding stresses in the zone of the joint. For example, the transverse residual tensile stresses in welded 70 • 15 mm welded plates of MI6S steel were only 25 MPa but in 300 • 26 mm samples they were close to the yield strength of the base metal. Therefore, in weld samples the scale effect in fatigue tests is revealed to a greater degree than in solid samples. This is confirmed by the results of our low-cycle fatigue experiments. In large solid samples of Yu3 steel the life in the corrosive medium is 1.6 times less and in large samples with facing with a depth of 50 and 75% of the sample thickness 1.75 and 2.0 times less than in medium size samples.

88

Technological methods of increasing the fatigue life of welded structures have been directed toward reducing the effective stress concentration and a change in the field of residual stresses [3, 4, 6, ii, 20-22]. Before considering the influence of production methods on the fatigue strength of weld joints, it is appropriate to remember [ii] that welding conditions are characterized by a combination of factors determining the conditions of occurrence of the welding process. The factors (parameters of the process) are divided into basic (strength of the current, its type and polarity, electrode diameter, arc voltage, welding speed) and secondary (gap depth of the electrode, composition and structure of the flux, type of electrode coating or protective gas, initial temperature of the base metal, position of the electrode and the part in space). It is obvious that the action of the welding factors cannot be considered independently of the object of application and therefore together with the welding parameters themselves it is necessary also to take into consideration the chemical composition and dimensions of the part to be welded, the form of preparation of the edges for welding, the chemical composition of the welding materials, flux, and coating, etc. In addition, it is necessary to take into consideration secondary processes occurring during welding, particularly deformations and stresses. Electric-arc finishing of weld joints, includin~ the application of additional fillet beads [3, 4, 6, Ii], creates in low-carbon and low-alloy steels the same effect as mechanical cleaning of joints. By a rational choice of the composition of the welding and finishing materials and the finishing methods, it is also possible to improve the shape of the joint and to increase the fatigue life of the weld joint. For example, in [ii] the possibility was shown of increasing the fatigue strength of weld joints by facing in the zones with significant stress concentration of a metal with a low modulus of elasticity (for austenitic steel E = 167 GPa). Facing in a zone of stress concentration with austenitic metal (Ebase met./Efac. = 200/167 = 1.20~ with alternating sign bending increases the fatigue limit of samples by 1.24 times, that is, proportionally to the ratio of the moduli of elasticity, and at the same time the zone of failure is displaced from the design stress raiser in the direction of the base metal. The finishing method has a substantial influence on the life (Fig. 6) of welded samples (Fig. 7a) of type 18KhNMA steel butt welded with subsequent finishing using various methods without facing. The optimum is a finishing current of 200-350 A. The material for finishing the joint also has a significant influence on the life of weld ssmples in low-cycle loading in a corrosive medium. In this case the optimum method of finishing may increase the low-cycle life by 1.5-1.8 times. The ted both the weld residual ial, the joint.

influence of finishing weld joints with a filler wire on low-cycle fatigue is relato a decrease in the geometric concentration of stresses as a result of smoothing joint--base metal transition and to redistribution of deformations and a decrease in weld stresses as the result of differences in the properties of the finishing materbase metal, and the metal of the joint and also local heating of the zone near the

Finishing of the joint was highly effective for T-shaped (Fig. 7b) weld joints of type 18KhNMA steel (Fig. 8). The effectiveness of working depends upon the welding and finishing materials. The maximum effect was found on samples welded with EP-704 wire under a layer of 48-OF-6M flux and finished with EP-647 wire. Welding with EP-647 in carbon dioxide and subsequent working with EP-647 wire provides good results. It is interesting to note that in finishing T-shaped weld joints with EP-647 wire, the finishing conditions have a significant influence on the life of the joint regardless of the type of base welding material. An increase in finishing current in the investigated range leads to a 1.5 times increase in life. In finishing with EI-981 wire the finishing current in this range does not play any role. Therefore, correctly chosen finishing conditions and material make it possible to substantially increase the low-cycle fatigue life of heavy plate-weld joints. Of the other welding factors to obtain smooth butt weld joints and increase their life, preparation of the edges if its area exceeds 40-50% of the area of facing and the use of coarse-grained flux are in practice applicable. The form of preparation of the edges (Xshaped, V-shaped, etc.) for welding of a butt joint [5] is not reflected on the fatigue limit of the joint. Therefore, the allowable stresses may be considered the same with any form of

89

preparation of the edges, nevertheless remembering that the least distortions of the structure occur in X-shaped preparation. In welding in the downhand position it is easier to provide ~ smooth Joint contour and better penetration and to avoid undercuts. Therefore, Joints made in the downhand position have a higher fatigue resistance as a rule. For example, the fatigue strength of butt Joints (with reinforcement of the joint) of low-carbon steels with transverse Joints made by manual arc welding in various spatial positions was 50-64% of the strength of a joint made in the downhand position [6]. With an increase in the gap [23] in a butt joint with asymmetric X-shaped preparation of the edges from 0 to 18 mm, a marked reduction in the cyclic strength is not found although with a gap or more that 9 mm cracks originated not only in the transition zone from the base metal to the joint but also in the center of the joint. A favorable change in the fields of residual welding stresses in the zones of weld joints may be provided by different technological methods [3, 4, 6, 20-22, 24-27]. They may be condltlonally divided into two groups, methods of general working of a structure or its elements and methods of local working of the zone of the weld joint. The first group includes stress relieving and overloading of structures by static, fatigue, and vibration loading and the second the creation in the weld joint of residual compressive stresses by strengthening work hardening, local heating, point or linear compression, microexplosion, laser treatment, etc. One of the highly effective and popular methods of strengthening working of weld joints of hull structures is shot peening. To study its influence on the low-cycle fatigue of weld joints, samples from full-size plates of Yu3 steel original plates and those with facings of different dimensions were peened with 1.5,mm-diameter type DSL shot using an AD-I machine. For designers and engineers the main problem in the design and production of welded structures is raising the strength of weld joints (static, dynamic, corrosion-fatigue) to the strength level of the base metal but further improvement in the properties of the weld joint is not always desirable since regardless of this failure will occur in the less strong base metal. In connection with this, the possibility of increasing the low-cycle fatigue resistance by shot peening was studied only on samples with facings with a short length of working portion, the llfe of which was much lower than that of the base metal (Fig. 4). During facing tions, unfavorable fuslon but also to fore, shot peening the facing, and B,

metal on prepared plates as the result of the different temperature condiresidual welding stresses occur not only in the base metal at the line of a significant degree in the side of the plate opposite the facing. ThereOf faced plates is done using two methods, A, from the side opposite to from both sides.

It is known [28] that shot peening of ground solid samples reduces to almost half their low cycle life, the reason for which is a marked increase in microunevenness. In low-cycle fatigue tests of "black" samples in a corrosive medium not a single crack appears on the working portion but a network of cracks formed from traces of rolling existing on the surface of the plate, a multitude of stress raisers. In cyclic loading the corrosive medium promotes the development of microcracks to macroscopic dimensions and the products of corrosion and the medium itself leads to their cleavage [29]. The increase in life in a corrosive medium of samples shot-peened from the side opposite the facing may be explained by the following. First, plates with a "black" surface were peened. In this case shot peening increases the low-cycle life, removing and strengthening the deep depressions, scale, tears, and other macro- and microdefects occurring during formation of the ingot and which under cyclic loads become, as a rule, sources of the origin of fatigue cracks [30]. Second, there is a decrease in residual welding stresses. Weld joints are distinguished by significant nonuniformity in the properties of individual zones and by significant residual welding stresses. For example, for the investigated Yu3 steel the residual tensile stresses close to facing reach 450 MPa [31]. The growth rate of fatigue cracks depends strongly upon the level of residual stresses [32]. For weld joints the location of defects and cracks relative to the weld joint is also important. It must be taken into consideration that the averagefatlgue crack growth rate and, consequently, the life depend not only upon the amounts of the residual stresses but also upon their distribution. A broad zone of tensile stresses significantly reduces the life of a weld joint [33].

90

In cyclic deformation nonuniformity of the physicomechanical properties of a weld joint causes redistribution of the deformations and stresses in the zone of a weld joint. At the same time, the individual zones of the weld Joint may differ in the average fatigue crack growth rate [34] and in total life [35] by an order of magnitude. Additional shot peening from the side of the facing markedly increases the life of faced samples of Yu3 steel (Fig. 5, curve I). Such an increase has been recorded for all samples regardless of the depth of facing. As a result of shot peening from the side of the facing in addition to surface strengthening of the facing and a reduction in residual stresses, there is [28] some equalization of the electrochemical properties of the facing and the base metal and welding of surface microcracks. Therefore, it may be concluded that shot peening is a reliable production method of increasing the low-cycle life of elements of heavy-plate structures repaired by facing. Among the special production methods of increasing the life of welded structures in corrosive media, we must mention the application of polymer and metallic coatings [4, 6, 36]. LITERATURE CITED 1. 2.

3. 4. 5. 6. 7.

8.

9.

i0.

ii. 12.

13.

14. 15. 16.

O. I. Steklov, The Strength of Welded Structures in Corrosive Media [in Russian], Mashinostroenie, Moscow (1976). V. S. Lifshits, E. E. Efendiev, V. P. Koval', and V. N. Kozyrev, "The influence of nonuniformity of the weld joints of pipe on their tendency toward sulfide cracking," Fiz.Khim. Mekh. Mater., No. 5, i02-104 (1979). I. V. Kudryavtsev and N. E. Naumchenkov, The Failure of Welded Structures from Fatigue [in Russian], Mashinostroenie, Moscow (1976). V. I. Trufyakov, The Fatigue of Weld Joints [in Russian], Naukova Dumka, Kiev (1973). V. H. Munze, The Fatigue Strength of Welded Steel Structures [Russian translation], S. V. Serensen and V. I. Trufyakov (eds.), Mashinostroenie, Moscow (1968). I . V . Kudryavtsev and N. E. Naumchenkov, The Fatigue of Welded Structures [in Russian], Mashinostroenie, Moscow (1976). V. P. Rudenko~ K. B. Katsov, V. G. Makarenko, and V. I. Kovalenko, A Machine for LowCycle Fatigue Testing of Heavy Plate Materials by Bending in Operating Media. Information Letter [in Russian], Atlas, Lvov (1977). G. V. Karpenko. A. B. Kuslitskii, K. B. Katsov, V. P. Rudenko, and I. V. Kokotailo, "A machine for low-cycle fatigue testing of materials," Tekhnol. Sudostr., No. 10, 15-16 (1974). G. V. Karpenko, K. B. Katsov, V. P. Rudenko, I. V. Kokotailo, G. I. Zarutskii, and V. G. Makarenko, "A machine for studying the influence of media on the low-cycle fatigue life of heavy plate samples," Fiz.-Khim. Mekh. Mater., No. 4, i13-i15 (1975). V. P. Rudenko, K. B. Katsov, V. I. Kovalenko, L. V. Grishchenko, A. I. Kornblyum, and V. S. Pavlov, "The stress distribution in elastoplastic deformation," Fiz.-Khim. Mekh. Mater., No. 6, 1!3-114 (1979). G . A . Bel'chuk, Weld Joints in Hull Structures [in Russian], Sudostroenie, Leningrad (19691. A. K. Vasil'ev, A. B. Zlochevskii, N. G. Tsyurikh, G. K. Sharshukov, and S. F. Yur'ev, "The influence of stress concentration on the low-cycle fatigue resistance of weld ....... joints," in: Questions of Shipbuilding. "Welding" Series [in Russian], No. 20 (1975), pp. 22-29. S . V . Serensen, R. M. Shneiderovich, A. P. Gusenkov, N. A. Makhutov, A. N. Romanov, A. N. Filatov, O. A. Levin, O, A. Bandin, and G~ K. Sharshukov, Strength in Low-Cycle Loading. Fundamentals of Methods of Calculation and Testing [in Russian], Nauka, Moscow (1975). R. B. Weibull, Design Taking Fatigue into Consideration [Russian translation], I. F. Obraztsov, Mashinostroenie, Moscow (1969). G. V. Karpenko. K. B. Katsov, I. V. Kokotailo, and V. P. Rudenko, The Low-Cycle Fatigue of Steel in Working Media [in Russian], Naukova Dumka, Kiev (1977). V. V. Larionov and P. T. Bogdyl', "An investigation of the deformed state of weld joints by the photoelastic coating method in relation to strength with a small number of load cycles," in: The Low-Cycle Fatigue of Welded Structures [in Russian], Izd. Leningrad~ Doma Nauch. Tekh. Prop., Leningrad (1973), pp. 63-67.

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17.

V. P. Rudenko, "The life of plate materials after elimination of corrosion defects by facing," Fiz.-Khim. Mekh. Mater., No. 6, 77-80 (1975). 18. Ted. B. Jefferson, "Weld deposit adds life to mill rolls," Weld. Des. Fabr., 52, 76-78 (1979). 19. V. I. Trufyakov, "The role of residual stresses in reducing the fatigue life of weld joints," Avtomat. Svarka, No. 5, 90-103 (1956). 20. J. W. Knight, "Improving the fatigue strength of fillet welded joints by grinding and peening," Weld. Res. Int., 8, No. 6, 519-540 (1978). 21. P. Candeland, "In situ heat treatment," FWP J., 18, No. 12, 7-17 (1978). 22. Tadahiro Umemoto and Shinji Tanaka, "Residual stress improvement by means of induction heating," IHI Eng. Rev., ii, No. 4, 11-20 (1978). 23. H. Paetzold, "EinfluB des Stegabstands auf die Schweigfestiqkeit von StumpfnNhten an Schillbaustahl des G~tegrades A," Schiff Hafen, 31, No. 2, 157-159 (1979). 24, B.V. Savchenkov, "Increasing the stability of the properties of faced metal after thermomeehanical treatment," Avtomat. Svarka, No. i0, 67-68 (1977). 25. Yu. A. Novikov and V. S. Zoteev, "The influence of preliminary plastic deformation on fatigue crack development in the zone near the joint of a butt weld joint," Svarochn. Proizvod., No. ii, 26-28 (1976). 26. G. V. Plyatsko, M. I. Moisa, and L. P. Karasev, "The use of a laser to remove residual welding stresses," Fiz.-Khim. Mekh. Mater., No. 6, 87-89 (1971). 27. E. Mryka, "Elimination of residual stresses with the use of loading and vibration," in: Modern Problems of Welding and Special Electrometallurgy [in Russian], Naukova Dumka, Kiev (1980). 28. I. P. Pistun, "The influence of machining and strengthening treatment on the low cycle fatigue llfe of constructional steels in active liquid media," Author's Abstract of Candidate's Thesis, Technical Sciences, Lvov (1977). 29. G. V. Karpenko, The Strength of Steel in a Corrosive Medium [in Russian], Mashgiz, Moscow-Kiev (1963). 30. V. F. Luk'yanov, Yu. G. Lyudmirskii, N. G. Tsyurikh, andS. F. Yur'ev, "The failure of sheet constructional steel in cyclic loading of it in a corrosive medium," Probl. Prochn., No. 3, 83-86 (1974). 31. O. G, Sokolov, K. B. Katsov, and G. V. Karpenko, Superplasticity and the Corrosion-Mechanical Strength of Two-Phase Iron-Manganese Alloys [in Russian], Naukova Dumka, Kiev

(1977), 32.

33. 34. 35.

36.

92

V. I. Trufyakov, P. P. Mikheev, and A. Z. Kuz'menko, "The influence of residual welding stresses on fatigue crack development in constructional steel," Avtomat. Svarka, No. I0, 6-7 (1977). G. Glinka, "The influence of the form of distribution of residual stresses on fatigue crack growth," Probl. Prochn., No. 5, 51-54 (1978). Yu. A. Novikov, V. S. Zoteev, and A. A. Gudkov, "Fatigue crack propagation in a weld joint," Probl. Prochn., No. 8, 54-75 (1976). K. K. Makhunov, V. V. Larionov, and Kh. M. Khanunov, "The low-cycle strength of weld joints of low'carbon and low-alloy steels in relation to the strength of the different zones," in: Questions of the Strength of Large Machine Parts [in Russian], Mashinostroenie, Moscow (1976), pp. 130-139. V. Gil'de, "Increasing the fatigue life of the weld joints of structures with the use of plastic coatings," Avtomat. Svarka, No. i, 23-27 (1965).