20.500.12556/RUL-135213 Grain size evolution and mechanical properties of Nb, V-Nb, and Ti-Nb boron type S1100QL steels Titanium additions are often used for boron factor and primary austenite grain size control in boron high- and ultra-high-strength alloys. Due to the risk of formation of coarse TiN during solidification the addition of titanium is limited in respect to nitrogen. The risk of coarse nitrides working as non-metallic inclusions formed in the last solidification front can degrade fatigue properties and weldability of the final product. In the presented study three microalloying systems with minor additions were tested, two without any titanium addition, to evaluate grain size evolution and mechanical properties with pre-defined as-cast, hot forging, hot rolling, and off-line heat-treatment strategy to meet demands for S1100QL steel. Microstructure evolution from hot-forged to final martensitic microstructure was observed, continuous cooling transformation diagrams of non-deformed austenite were constructed for off-line heat treatment, and the mechanical properties of Nb and V–Nb were compared to Ti–Nb microalloying system with a limited titanium addition. Using the parameters in the laboratory environment all three micro-alloying systems can provide needed mechanical properties, especially the Ti–Nb system can be successfully replaced with V–Nb having the highest response in tensile properties and still obtaining satisfying toughness of 27 J at −40 °C using Charpy V-notch samples. S1100QL grain size microalloying vanadium niobium titanium boron mechanical properties microstructure non-metallic inclusion true false true Angleški jezik Ni določen Članek v reviji 2022-03-01 09:56:18 2022-03-01 09:56:19 2022-09-14 04:12:12 0000-00-00 00:00:00 2021 0 0 16 str. iss. 3, art. 492 Vol. 11 2021 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 620.1/.2 2075-4701 10.3390/met11030492 55642883 RAZ_Foder_Jan_2021.pdf RAZ_Foder_Jan_2021.pdf 1 EF8DF252665AC3A9554545716D88AFE5 16ff2b26af043086bdb4511eb6c6572b39e7a43508a5e050ce3b08fbebe1a165 85dfc2d6-993f-11ec-abdb-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=154134 https://www.mdpi.com/2075-4701/11/3/492 1 3281a473-993d-11ec-abdb-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=154133 Naravoslovnotehniška fakulteta 0 0 0