| 2003 №02 (03) | 2003 №02 (05) |
The Paton Welding Journal, 2003, #2, 17-21 pages
Structural transformations and weldability of hardening high-strength steel 20KhN4FA
V.Yu. Skulsky, A.K. Tsaryuk, V.G. Vasiliev, G.N. Strizhius
E.O. Paton Electric Welding Institute of the NASU 11 Kazymyr Malevych Str., 03150, Kyiv, Ukraine.Abstract
Transformation of austenite in steel 20KhN4FA (GOST 4543-71) under continuous cooling conditions has been studied. Hardening of steel to form fully martensitic structure takes place at cooling rates of more than 20 °C/s, while partially bainitic decomposition occurs at lower cooling rates. Preheating to a temperature of 250-300 °C leads to a dramatic increase in cold crack resistance, which seems to be associated with sufficient conditions ensured for the -bainite transformation to take place. The latter is accompanied by partial self-tempering and increase in ductility of the HAZ metal of a welded joint. Issues related to selection of the preheating temperature are also considered.
Keywords: arc welding, hardening steels, structural transformations, cold cracks, implant method, preheating
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