Izvestia Vysshikh Uchebnykh Zawedeniy. Yadernaya Energetika

The peer-reviewed scientific and technology journal. ISSN: 0204-3327

Technology of thermal welding with ultrasonic weld joint treatment as applied to NPP formworks

6/21/2017 2017 - #02 Physics in nuclear power engineering

Minin S.I.

DOI: https://doi.org/10.26583/npe.2017.2.12

UDC: 534-16

Increasing the strength, reliability and durability of welded structures is an important problem in welding engineering. A significant influence is exerted by residual stresses. Uneven heating of the product during welding causes its uneven temperature deformation. The product material solidity prevents the free temperature deformation of its individual parts, resulting in the formation of stresses and plastic deformation of some parts of the joint metal during welding, and after cooling, welding stresses and deformations remain in the product.

Residual stresses are caused by different linear or volumetric deformations of the adjacent metal masses; these deformations are formed in structures (products) without external forces. The differences of residual stresses which arise during various technological processes are manifested in the character of their distribution in macro-and micro-volumes of the product as well as in the specific factors leading to heterogeneous deformations.

The paper describes an innovative technology of thermal welding with ultrasonic weld joint treatment as applied to aluminum sliding formworks used in NPP construction. Ultrasonic treatment in the process of welding greatly increases the strength of formwork weld joints by reducing their residual stresses, grain size and degassing. The structure and properties of aluminum welds become identical to the base metal. Thermal welding with ultrasonic weld joint treatment will improve the reliability of welded joints and increase their time in service. The results of theoretical and experimental studies are presented relating to the ultrasonic effects on the weld joints and heat-affected zone. The influence of ultrasound during the welding process improves the strength characteristics of alloy AD31 weld joints, prevents the formation of stress concentrators and significantly reduces the likelihood of discontinuities in weld joints.

References

  1. Statnikov E.S., Muktupavels V.O. The technology of ultrasonic impact treatment as a means of increased reliability and durability of welded metal structures. Welding production. 2003, no. 4, pp. 25-29 (in Russian).
  2. Marushchak P.O., Salo U.V., Bishchak R.T., Poberezhnyi L.Ya. Study of Main Gas Pipeline Steel Strain Hardening After Prolonged Operation. Chemical and Petroleum Engineering. May 2014, v. 50, iss. 1-2, pp. 58-61.
  3. Pleshanov V.S, Kibitkin V.V, Panin V.E. Mesomechanics and Fatigue Fracture for polycrystals with macroconcentratrs. Theoretical and Applied Fracture Mechanics. 1998, v. 30, no. 1, pp. 13-18.
  4. Blaha F., Langenecker В. Naturwis. 1955, v. 20, no. 9, p. 556.
  5. Prokopenko G.I., Lyatun T.A. Study of Surface Hardening Conditions by Means of Ultrasound. Physics and Chemistry of Material Processing. 1977, no. 3, p. 91.
  6. Kudryavtsev Y., Kleiman J., Prokopenko G., Mikheev P. and Knysh V. Optimum Application of Ultrasonic Peening. SEM Annual Conference and Exposition: Experimental Mechanics in Emerging Technologies. Portland. Oregon. USA, June 4-6, 2001, pp. 179-182.
  7. Trofimov A.I., Trofimov M.A., Minin S.I. The pattern of change in the magnitude of residual stresses in metals and alloys when exposed to ultrasound. Scientific discovery. Diploma №375, 2009 (in Russian).
  8. Trofimov A.I. Physical principles of ultrasonic methods for relieving residual stresses in welded joints of metals and alloys. Moscow. Energoatomizdat Publ., 2009, 239 p. (in Russian).
  9. Trofimov A.I., Trofimov M.A., Minin S.I., Kirillov Yu.A. Innovative ultrasonic technology to increase the service life of NPP equipment in its manufacture. Izvestiya vuzov. Yadernaya energetika. 2012, no. 2, pp. 48-54 (in Russian).
  10. Larionov V.P., Kuz’min V.R., Sleptsov O.I. Cold resistance of materials and elements of structures. Results and prospects. Novosibirsk. Nauka Publ., 2005, 290 p. (in Russian).
  11. Trofimov A.I., Minin S.I., Trofimov M.A., Vasilkovsky D.V., Kosyrev K.A. Automated ultrasonic system of removing residual stresses in welded connections of circulating pipelines of nuclear power plant. Vestnik Rossijskoj akademii estestvennykh nauk. 2015, no. 1, pp. 3-5 (in Russian).
  12. Trofimov A.I., Minin S.I., Trofimov M.A. Automated ultrasonic system of removing residual stresses in welded connections of circulating pipelines of nuclear power plants. Izvestiya vuzov. Yadernaya energetika. 2016, no. 3, pp. 13-19 (in Russian).
  13. Abramov O.V., Gorbenko I.G., Svehla S.A. Ultrasonic treatment of materials. Moscow. Mashinostroenie Publ., 1984. 280 p. (in Russian).
  14. Abramov O.V. Crystallization of the metals in ultrasonic field. Moscow. Metallurgiya Publ., 1972. 256 p. (in Russian).
  15. Kulemin A.V. Ultrasound and Diffusion in Metals. Moscow. Mashinostroenie Publ., 1978. 200 p. (in Russian).
  16. Kudryavtsev P.I. Residual welding stresses and strength of connections. Moscow. Mashinostroenie Publ., 1964. 96 p. (in Russian).
  17. Trofimov A.I., Minin S.I., Trofimov M.A. Automated ultrasonic system of removing residual stresses in welded connections of circulating pipelines of nuclear power plants. Izvestiya vuzov. Yadernaya energetika. 2016, no. 3, pp. 13-19 (in Russian).

aluminum alloy welding residual stress influence of ultrasound heat-affected zone