25 KB615 KB23 KB200020242010Jenko, MonikaKosec, GorazdSmolej, AntonVodopivec, FrancVojvodič-Tuma, Jelenaletnik:44številka:6str. 349-355ISSN:1580-2949COBISSID:841898URN:URN:NBN:SI:doc-H0QPIKMNenInštitut za kovinske materiale in tehnologijeMateriali in tehnologijebainitmartenzitmikrolegirano jeklotemperatura cepilnega prelomatrdotazarezna žilavostEffect of 3 s reheating on Charpy notch toughness and hardness of martensite and lower bainite| Vpliv 3 s pogrevanja na Charpyjevo zarezno žilavost in trdoto martenzita in spodnjega bainita|The 0.1C 0.032Nb fine grained steel was heat treated to fine and coarse grained lower bainite and martensite. Half of specimens was reheated for 3 s at 750 °C with current conduction. Charpy notch tests were performed in temperatr!ure range from -200 °C to 60 °C, room temperature hardness determined and microstructure and fracture surface examined with SEM. Notch toughness and transition temperature are similar for lower bainite and delivered steel and much lower for martensite. After reheating, noth toughness was decreased for about ten times for lower bainite and the cleavage temperature increased for about 80 °C. Both changes were much lower for martensite and for as delivered steel. The effect of reheating on hardness was different for different microstructure and much smaller as for notch toughnessV drobnozrnatem jeklu z 0.1 C in 0.32 Nb je bila s toplotno obdelavo ustvarjena mikrostruktura iz martenzita in spodnjega bainita. Polovica preizkušancev je bila nato znova segreta 3 s pri 750 °C z električnim tokom. Charpy preizkusi so bili izvršeni v razponu temperature od -200 °C do +60 °C, trdota izmerjena pri sobni temperaturi, mikrostruktura in prelomne površine pa pregledane v SEM. Zarezna žilavost in prehodna temperatura sta podobni za dobavljeno jeklo in spodnji bajnit in nižji za martenzit. Po ponovnem segretju je bila zarezna žilavost zmanjšana za okoli 10 krat, temperatura cepilnega preloma pa povečana za okoli 80 °C za spodnji bainit. Obe spremembi sta bili mnogo manjši pri martemnzitu. Vpliv ponovnega segravanja je bil manjši pri trdoti in različen pri različni mikrostrukturiTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije