HOW ULTRAFINE PARTICLES OF TUNGSTEN MONOCARBIDE AFFECT THE WELDED-METAL STRUCTURE

M. A. Sheksheyev, S. V. Mikhaylitsyn, A. B. Sychkov, A. N. Emelyushin, E. N. Shiryayeva

Abstract


Statement of problem (relevance): the paper describes the problem of structure formation in welding low-carbon low-alloy steels. The weld metal structure forms in a complex thermal environment that predetermines the operating performance of the metal. Emergence of large columnar crystals in welds poses a potential hazard, as such structures may under certain conditions concentrate the tension and trigger destruction. The paper dwells upon the possibility of controlling the primary structure of welded metal by injecting nano- and ultrafine particles of a refractory material into the weld pool. The objective is to study how nano- and ultrafine particles of tungsten monocarbide WC) affect the structure of welded metal. Methods used: the researchers have carried out a laboratory experiment consisting in making electrodes with a coating containing a varying amount of ultrafine WC powder, then making welded-metal samples and studying the samples by optical microscopy (a Micromed-Met microscope) as well as measuring the Vickers hardness (a HV-1000 device). The novelty of this research consists in gathering new data on how the concentration of ultrafine WC powder in the electrode coating affects the structure of welded metal. The results: the structure of metal welded by electrodes with a coating containing 0, 0.02, or 0.2 % of WC powder (% of drymix weight) features columnar crystals surrounded by a grid of peripheral ferrite formed along the primary-grain boundaries. Needle-like inclusions of Widmanstätten ferrite sprouting from the crystal edges to the crystal center are observed along with bainitic structures. Electrodes with a coating containing 0.4% of WC powder produce welded metal of a finer cellular structure in the form of equiaxed crystals. The hardness of the welded-metal samples is within 184 to 189 HV. Practical significance: the research has produced data necessary for creating new coated electrodes for welding and surfacing low-carbon low-alloy steels.

Keywords


coated electrode; welding; surfacing; tungsten carbide; nanopowder; refractory compounds; modified; microstructure; mechanical properties

References


Kuznecov M.A., Zernin E.A. [Nanotechnologies and Nanomaterials in the Welding Industry]. Svarochnoe proizvodstvo, 2010, no. 12, pp. 23–26. (in Russ.)

Gorynin I.V. [Research and Development of FSUE Central Research Institute KM “Prometheus” in the Field of Structural Nanomaterials]. Rossijskie nanotehnologii, 200, no. 3–4, pp. 36–57. (in Russ.)

Poleckov P.P., Hakimullin K. et al. [Purpose and Scope of Ultra-Cold-Resistant Nanostructured Sheet Metal]. Vestnik Magnitogorskogo gosudarstvennogo tehnicheskogo universiteta, 2017, vol. 15, no. 2, pp. 85–88. (in Russ.) DOI: 10.18503/1995-2732-2017-15-2-85-88

Gol'dshtejn Ja.E., Mizin V.G. Inokulirovanie zhelezo-uglerodistyh splavov [Inoculation of Iron-Carbon Alloys]. Moscow, Metallurgija Publ., 1993. 416 p.

Volchenko V.N., Jampol'skij V.M., Vinokurov V.A. et al., Frolov V.V. (Ed.). Teorija svarochnyh processov [Theory of Welding Processes]. Moscow, Vysshaja shkola Publ., 1988. 559 p.

Sokolov G.N., Lysak V.I. et al. [Phenomenological Model of the Formation of Crystallization Centers in a Metal Melt during Welding under the Influence of Ultrafine Refractory Components], Voprosy materialovedenija, 2015, no. 4, pp. 159–168. (in Russ.)

Sokolov G.N., Lysak V.I. et al. [Modification of the Structure of the Weld Metal with Nanodispersed Tungsten Carbides]. Fizika i himija obrabotki materialov, 2009, no. 6, pp. 41–47. (in Russ.)

Samsonov G.V., Vinickij I.M. Tugoplavkie soedinenija [Refractory Compounds]. Moscow, Metallurgija Publ., 1976. 560 p.

Storms Je. Tugoplavkie karbidy [Refractory Carbides]. Moscow, Atomizdat Publ., 1970. 304 p.

Sokolov G.N., Lysak V.I. et al. [Effect of Nanodispersed Carbides WC and Nickel on the Structure and Properties of the Weld Metal]. Svarka i diagnostika, 2011, no. 3, pp. 36–38. (in Russ.)

Samsonov G.V., Upadhaya G.Sh., Neshpor V.S. Fizicheskoe materialovedenie karbidov [Physical Materials Carbides]. Kiyev, Naukova dumka Publ., 1974. 454 p.

Makarenko V.D., Murav'ev K.A. [Features Manual Arc Welding of Root Welds Butt Position of Pipelines Operating in Western Siberia]. Svarochnoye proizvodstvo, 2005, no. 12, pp. 38–41. (in Russ.)

Zvereva I.N., Kartunov A.D., Platov S.I., Mikhaylitsyn S.V., Sheksheev M.A. Electrodes for Manual Arc Welding in Oil and Gas Complex. Bulletin of the South Ural State University. Ser. Metallurgy, 2015, vol. 15, no. 1, pp. 92–95. (in Russ.)

Mikhaylitsyn S.V., Sheksheev M.A. et al. The Research on Surface Properties of Welding Slags and Electrode Coatings. Journal of Chemical Technology and Metallurgy, 2017, vol. 52, no. 4, pp. 724–730.

Mikhailitsyn S.V., Sheksheev M.A., Platov S.I., Emelyushin A.N., Naumov S.V. [Investigation of Viscosity of Liquid Welding Slags and Melts of Electrode Coatings]. Izvestiya Visshikh Uchebnykh Zavedenii. Chernaya Metallurgiya, 2018, vol. 61, no. 4, pp. 280–287. (in Russ.) DOI: 10.17073/0368-0797-2018-4-280-287




DOI: http://dx.doi.org/10.14529/met180414

Refbacks

  • There are currently no refbacks.


Bookmark and Share