Hot compression of RAV 4980 steel

Jeklo RAV 4980 v svetu poznano pod imenom A-286. To je je železo-nikelj-kromova zlitina z dodatki molibdena in titana. Spada med avstenitna nerjavna jekla. Zlitino odlikujejo visoke vrednosti za trdnost ter odpornost proti koroziji in oksidaciji do zelo visokih temperatur. Zaradi svojih dobrih mehanskih lastnostih se uporablja predvsem v letalski, avtomobilski in naftni industriji. Namen diplomske naloge je bil raziskati, kako vhodni parametri preoblikovanja vplivajo na mikrostrukturo in trdoto jekla. Najprej smo izvedli tlačne preizkuse v vročem, pri čemer smo variirali hitrost in temperaturo deformacije. Velikost deformacije tlačnih vzorcev je bila konstantna. Deformirane tlačne vzorce smo prerezali v aksialni smeri, izdelali obruse in s pomočjo svetlobnega mikroskopa študirali mikrostrukturo. Prav tako smo izbrani vzorec pregledali še z vrstičnim elektronskim mikroskopom. Preiskovano jeklo pod temperaturo 1000 °C izkazuje nizko stopnjo dinamične rekristalizacije, kar vpliva tako na preoblikovalnost kot tudi na utrjevanje materiala.RAV 4980 steel, known as A-286 in the world, is an iron-nickel-chromium alloy with the addition of molybdenum and titanium and belongs to austenitic stainless steels. This steel is characterized by excellent strength and resistance to corrosion and oxidation up to very high temperatures. Due to its good mechanical properties, it is mainly used in aviation, automobile, and oil industry. The purpose of the thesis was to investigate the effects of the input deformation parameters on workability and recrystallization. These hot compression tests we carried whereas strain rate and temperature varied. Value of strain was constant for all of the compressed samples. The deformed samples were cut in the axial direction and the observed surface area was prepared for light microscopy. The sample was observed also using scanning electron microscope. The low level of dynamic recrystallization in the compressed samples below 1000 °C was detected