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We have studied the effect of electroslag remelting on the content and composition of non-metallic inclusions. It was found that a decrease in the non-metallic inclusion content occurred during the electroslag remelting. A change in the chemical composition of the non-metallic inclusions was observed, while the aluminum and calcium contents were increased. The complexity of the inclusions also increased, as there were fewer single-phase inclusions after the electroslag remelting process. Based on the results and a thermodynamic assessment of the formation of the non-metallic inclusions, a mechanism for inclusion behavior during electroslag remelting has been proposed.

This research provides an overview of the structural changes that occur during the hot rolling of the nickel superalloy Inconel 625. It is well known that microstructure control is of paramount importance concerning the mechanical properties of a material. The microstructure also plays an important role in processing materials at elevated temperature. In this work the hot-rolling behaviour of the Inconel 625 superalloy has been investigated. The specimens were hot rolled at a temperature of 1200°C using different numbers of passes. During the hot rolling the loads were measured and recorded. A light microscope and an electron microscope, employing the electron-backscatter-diffraction (EBSD) technique, were employed to investigate the microstructure evolution, revealing a necklace dynamic-recrystallization mechanism. Keywords: nickel superalloy, hot rolling, dynamic recrystallization, necklace mechanism Raziskava obsega pregled strukturnih sprememb, ki se pojavijo med vro~im valjanjem nikljeve superzlitine Inconel 625. Znano je, da je kontrola mikrostrukture odlo~ilnega pomena za mehanske lastnosti materiala. Mikrostruktura ima pomemben vpliv na predelavo materiala pri povi{anih temperaturah. Preu~evali smo superzlitino Inconel 625 med vro~im valjanjem. Vzorci so bili vro~e valjani pri temperaturi 1200°C z razli~nimi {tevili prevlekov, med poizkusi smo merili tudi sile valjanja. Vzorce smo preiskali s svetlobnim in elektronskim mikroskopom s tehniko difrakcije povratno sipanih elektronov (EBSD). Raziskali smo razvoj mikrostrukture in potrdili dinami~no rekristalizacijo preko "mehanizma ogrlice".

The changes to the microstructure of the duplex stainless steel SAF 2205 during hot tensile tests were investigated. The dominant restoration mechanisms for ferrite and austenite were dynamic recovery (DRV) and dynamic recrystallization (DRX), respectively. Also, the effect of temperature on the deleterious phase precipitation was investigated. The specimens were tested with hot tensile deformation tests in the temperature range from 800°C to 1100°C. The tensile strength of the investigated steel decreased rapidly in the temperature range from 800°C to 950°C and slowly at the testing temperatures from 1000°C to 1100°C. It was found that SAF 2205 has excellent hot-working properties at temperatures between 950°C and 1100°C. The differences in the mechanical properties of austenite and ferrite along with the precipitation of the s-phase represent the most important restrictions during hot working. Optical microscopy was used for the microstructure-evolution analysis in the duplex stainless steel during the hot tensile tests. Keywords: duplex stainless steel, hot tensile test, microstructural evolution, intermetallic phases, s-phase Preiskovali smo spremembe mikrostrukture dupleks nerjavnega jekla SAF 2205 med vro~imi nateznimi preskusi. Prevladujo~a mehanizma meh~anja v feritu in avstenitu sta bila dinami~na poprava in/ali dinami~na rekristalizacija. V dupleks nerjavnem jeklu je bil raziskan vpliv temperature na izlo~anje {kodljivih faz. Vzorce smo vro~e natezno presku{ali v temperaturnem obmo~ju med 800°C in 1100°C. Natezna trdnost preiskanega jekla se je hitro zni`ala v temperaturnem obmo~ju med 800°C in 950°C ter po~asneje pri temperaturah preskusov med 1000°C in 1100°C. Ugotovili smo, da ima SAF 2205 odli~ne vro~e preoblikovalne lastnosti v temperaturnem obmo~ju med 950°C in 1100°C. Najve~je omejitve pri preoblikovanju predstavljajo razlike v mehanskih lastnostih med avstenitom in feritom ter izlo~anje s-faze. V raziskavi je bila uporabljena opti~na mikroskopija za analizo razvoja mikrostrukture v dupleks nerjavnem jeklu med vro~imi nateznimi preskusi. Klju~ne besede: dupleks nerjavno jeklo, vro~i natezni preskusi, razvoj mikrostrukture, intermetalne faze, s-faza

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