International Scientific-Technical and Production Journal October 2010 # 10 English translation of the monthly «Avtomaticheskaya Svarka» (Automatic Welding) journal published in Russian since 1948 Founders: E.O. Paton Electric Welding Institute of the NAS of Ukraine Publisher: International Association «Welding» International Association «Welding» Editor-in-Chief B.E.Paton CONTENTS Editorial board: Yu.S.Borisov V.F.Khorunov A.Ya.Ishchenko I.V.Krivtsun SCIENTIFIC AND TECHNICAL B.V.Khitrovskaya L.M.Lobanov V.I.Kirian A.A.Mazur Kovalenko D.V., Pavlyak D.A., Sudnik V.A. and Kovalenko I.V. S.I.Kuchuk-Yatsenko Yu.N.Lankin I.K.Pokhodnya Adequacy of thermohydrodynamic model of through V.N.Lipodaev V.D.Poznyakov penetration in TIG and A-TIG welding of Nimonic-75 nickel V.I.Makhnenko K.A.Yushchenko O.K.Nazarenko A.T.Zelnichenko alloy .................................................................................................... 2 I.A.Ryabtsev Makhnenko V.I., But V.S., Kozlitina S.S., Dzyubak L.I. and Olejnik O.I. Optimal reduction of working pressure in pipelines for welding repair of thinning regions ................................................... 6 International editorial council: Radkevich I.A., Shvab S.L., Prilutsky V.P. and Akhonin S.V. N.P.Alyoshin (Russia) U.Diltey (Germany) Peculiarities of arc control by external magnetic field (Review) ............. 10 Guan Qiao (China) D. von Hofe (Germany) Poklyatsky A.G., Chajka A.A., Klochkov I.N. and Yavorskaya V.I.Lysak (Russia) M.R. Friction stir welding of aluminum alloys of different N.I.Nikiforov (Russia) B.E.Paton (Ukraine) alloying systems ................................................................................. 13 Ya.Pilarczyk (Poland) P.Seyffarth (Germany) Maksymova S.V., Khorunov V.F. and Shonin V.A. Mechanical G.A.Turichin (Russia) properties of brazed joints on dispersion-strengthened copper Zhang Yanmin (China) A.S.Zubchenko (Russia) alloy ................................................................................................... 17 Borisova A.L., Tunik A.Yu., Adeeva L.I., Grishchenko A.V., Promotion group: V.N.Lipodaev, V.I.Lokteva Tsymbalistaya T.V. and Kolomytsev M.V. Thermal-barrier A.T.Zelnichenko (exec. director) multilayer plasma coatings ZrO —NiCrAlY ............................................. 22 Translators: 2 A.A.Fomin, O.S.Kurochko, I.N.Kutianova, T.K.Vasilenko PE «Melnik A.M.» INDUSTRIAL Editor N.A.Dmitrieva Shelyagin V.D., Khaskin V.Yu., Bernatsky A.V. and Siora A.V. Electron galley: D.I.Sereda, T.Yu.Snegiryova Prospects of application of laser and hybrid technologies of welding steels to increase service life of pipelines ............................... 29 Address: Knysh V.V., Solovej S.A. and Kuzmenko A.Z. Improvement of E.O. Paton Electric Welding Institute, International Association «Welding», cyclic fatigue life of welded joints with accumulated fatigue 11, Bozhenko str., 03680, Kyiv, Ukraine damage by high-frequency peening .................................................... 33 Tel.: (38044) 287 67 57 Fax: (38044) 528 04 86 Lebedev V.A. Tendencies in development of mechanized E-mail: [email protected] welding with controlled transfer of electrode metal (Review) ................ 37 http://www.nas.gov.ua/pwj State Registration Certificate KV 4790 of 09.01.2001 BRIEF INFORMATION Bondarev A.A., Tyurin Yu.N., Duda I.M. and Pogrebnyak A.D. Subscriptions: $324, 12 issues per year, Properties of Al2O3 + Cr + TiN coatings after electron beam postage and packaging included. treatment ........................................................................................... 45 Back issues available. All rights reserved. News .................................................................................................. 47 This publication and each of the articles contained herein are protected by copyright. Permission to reproduce material contained in this journal must be obtained in writing from NEWS the Publisher. Copies of individual articles may be obtained Ukrainian-German Workshop «Plasma and ELectron Beam from the Publisher. Technologies for Protective Coatings» ................................................. 48 © PWI, International Association «Welding», 2010 ADEQUACY OF THERMOHYDRODYNAMIC MODEL OF THROUGH PENETRATION IN TIG AND A-TIG WELDING OF NIMONIC-75 NICKEL ALLOY* D.V. KOVALENKO1, D.A. PAVLYAK2, V.A. SUDNIK2 and I.V. KOVALENKO1 1E.O. Paton Electric Welding Institute, NASU, Kiev, Ukraine 2Tula State University, Tula, Russian Federation Results of experiments on weld formation in TIG and A-TIG welding of Nimonic-75 alloy, and results of computer simulation of the effect of convection on «sand glass» shape of weld are presented. The experiments were carried out with and without activating flux PATIG Nim-75-A on 3.15 mm thick plates. Adequacy of the model was evaluated by comparing the sizes of the real and simulated weld sections. The causes of recirculation flows were analyzed. Correlation of the experimental and computation data was revealed. Keywords: TIG and A-TIG welding, nickel alloy, penetra- termined. It is established that arc contraction does tion, mathematical model, adequacy of mathematical model not affect austenitic steel penetration, but it should Positive results connected with an abrupt increase of be taken into account as an auxiliary factor [10, 11]. penetration depth at activating flux deposition on the It was proved here that electromagnetic convection surface of metal to be welded in TIG welding (A-TIG promotes deep penetration [12] and the centrifugal process ) of titanium obtained at the E.O. Paton Elec- component of the electromagnetic force is the domi- tric Welding Institute [1, 2] stimulated investigations nating factor of penetration [13]. Published results on arc column contraction in TIG welding of steels are given only for the simplest axisymmetrical case of and other materials [3—5]. a stationary heat source of incomplete penetration on Study [6] marked the beginning of investigations a stationary item from austenitic steel. of convection in welding. This work is devoted to the Technology of A-TIG welding of Nimonic-75 nickel influence of surfactants on penetration depth. Work alloy was tried out for the first time at PWI [14]. It [7] provides experimental proof of the postulates of is based on application of a short (1.5 mm) arc and [6] on the key factor in penetration depth, namely, activating salt-oxide flux PATIG Nim-75-A, contain- change of the sigh of temperature coefficient of surface ing metal fluorides and oxides. Fluorides promote arc tension dσ/dT from negative to positive sign. Addi- contraction [5] and influence development of physical tion of surfactants lowers surface tension at melting processes in it [15, 16]. Fluoride fluxes allow welding temperature, and values of dσ/dT coefficient become titanium sheets of up to 8 mm thickness [17, 18]. A positive. However, at temperature increase up to team of scientists led by B.E. Paton [19] developed 1900 °C, surface tension reaches values characteristic a theoretical model of arc contraction by fluoride for pure metal with a maximum at critical tempera- fluxes. For sodium fluoride NaF at welding current ture, and values of dσ/dT coefficient again become Iw = 100 A value of anode spot radius ra ≈ 1.5 mm negative, as for pure metal. was obtained. World’s first two-dimensional model of weld pool Another nickel alloy Nimonic-263 was welded over convection [8], created in 1983, provided theoretical a layer of isolated titanium oxides and their mixtures, confirmation of the postulates of [6] and showed that and the welding process was simulated using Marangoni surface tension forces are predominating, PHOENICS program [20]. Calculation results dif- and together with the Lorentz electromagnetic forces fered from experimental data. they are responsible for appearance of double eddy Computer simulation has recently become the main regions. Later it was established [9] that the sign of method of scientific investigations. Program code de- thermal concentration dependence of surface tension velopers and experimenters using such programs, face and its values determine the direction of convective the following question: how the error of simulation heat transfer under the arc and number of vortices. results should be assessed? Computer simulation ends Simulation of the role of electromagnetic forces in by prediction of the result of welding, and the most A-TIG welding is carried on, and the nature of the important characteristic of the prediction is the con- mechanism of this phenomenon still has not been de- fidence level. According to [2] prediction error is a * Published by the materials of a paper presented at the V International Conference on Mathematical Simulation and Information Technologies in Welding and Related Technologies (May 25—28, 2010, Katsively vil., Crimea, Ukraine). © D.V. KOVALENKO, D.A. PAVLYAK, V.A. SUDNIK and I.V. KOVALENKO, 2010 2 10/2010 vector sum of errors of simulation and experiment, allowing for the normal random distribution of data. The significance of the discrepancy between the results of simulation (prediction) and experimental data is determined by statistical criteria, for instance in com- Figure 1. Transverse macrosections of through-penetration welds parison of dispersions by Fisher criterion [21], or at made on Nimonic-75 alloy by A-TIG welding at Iw = 100 A (a) and unknown dispersion (often the case in practice) by TIG welding at Iw = 180 A (b) at the same (200 mm/min) welding Student criterion