Naslov
Transformation of austenite during isothermal annealing at 600-900°C for heat resistant stainless steel

Autori
Kosec, Ladislav ; Šavli, Štefan ; Kožuh, Stjepan ; Holjevac Grgurić, Tamara ; Nagode, Aleš ; Kosec, Gorazd ; Gojić, Mirko

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
POLYCHAR 20 : World Forum Advanced Materials : book of abstracts / Rogošić, Marko ; Macan, Jelena - Zagreb : Fakultet kemijskog inženjerstva i tehnologije Sveučilišta u Zagrebu, 2012, 268-268

ISBN
978-953-6470-57-0

Skup
POLYCHAR 20 : World Forum on Advanced Materials

Mjesto i datum
Dubrovnik, Hrvatska, 26.03.2012. - 30.03.2012

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
heat resistant stainless steel ; isothermal annealing ; microstructure ; microhardness ; fractography.

Sažetak
In this work the results of the transformation kinetics of austenite heat resistant stainless steel with 2.27 wt.% silicon were presented. This work concerns the microstructural and fractography analysis during isothermal heat treatment of the steel using optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). Firstly the steel was solution annealed at 1100 °C for 15 minutes to obtain a homogeneous starting conditions. After that, test samples were isothermal annealed in the temperature range from 600 to 900 °C at different annealing times (from 1 to 956 hours). Microhardness of samples was performed by Vickers method (HV0.3). Results of microstructural and fractography analysis as well as the hardness before and after isothermal heat treatment are shown. Thermodynamic calculation of equilibrium phases using ThermoCalc computer program was performed. It was found that the microstructure of steel after isothermal annealing was consisted of austenite and sigma phase. This phase was observed both at grain boundaries and within the austenite grains. In this case the formation of sigma phase is directly from austenite. Initial precipitation of the sigma phase took place along austenite grain boundaries. Morphology of sigma phase is spherical-oval like. With longer times the sigma phase continued to grow in size to agglomerate and coalesce in the form large angular particles, sometimes clustered at grain boundaries. At temperature of 600 °C the hardness becomes increasing after annealing of 48 hours, while in the temperature range 700-900 °C the hardness increases with annealing times higher from 8 hours.

Izvorni jezik
Engleski

Znanstvena područja
Kemijsko inženjerstvo, Metalurgija

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