24 KB1259 KB20 KB200020242013Adámek, JanJenko, DarjaJurči, PeterPrikner, OtakarSalabová, PetraSobotová, JanaŠuštaršič, Borivojštevilka:1letnik:47str. 93-98ISSN:1580-2949COBISSID:954538URN:URN:NBN:SI:doc-IJYMRQUTenInštitut za kovinske materiale in tehnologijeMateriali in tehnologijeizločkijeklokriogena obdelavatoplotna obdelavaDiagnostics of the microstructural changes in sub-zero-processed Vanadis 6 P/M ledeburitic tool steel| Diagnostika sprememb mikrostrukture pri kriogeni obdelavi P/M ledeburitnega orodnega jekla Vanadis 6|Specimens made from P/M Vanadis 6 cold-work steel were austenitized, quenched and tempered for various combinations of the parameters. The selected sets of samples, also in the sub-zero range, were treated at a temperature of -196 °C after quenching. The microstructure was investigated as a function of the austenitizing temperature and the parameters of the sub-zero processing using transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction. It was found that the as-quenched microstructure is composed of martensite, retained austenite and carbides. The sub-zero processing reduced the amount of retained austenite and led to an increase in the tetragonality of the martensitic lattice. As a result, the hardness of the material was higher by 2 HRc before the tempering of the samples after the sub-zero processing, but the hardness of the sub-zero-processed material after tempering is about 2.5 HRc lower than that of the non-sub-zero-processed steel. Based on the facts that the sub-zero-processed steel contained less retained austenite and an unknown amount of the expected nano-precipitates, we expected it to have a lower capability to manifest the secondary-hardening effectVzorci, izdelani iz jekla za delo v hladnem P/M Vanadis 6, so bili avstenitizirani, kaljeni in popuščani pri različnih kombinacijah parametrov. Izbrana skupina vzorcev je bila obdelana v kriogenem področju pri temperaturi -196 °C po kaljenju. Preiskana je bila mikrostruktura v odvisnosti od temperature avstenitizacije in parametrov kriogene obdelave, s presevno elektronsko mikroskopijo (TEM), visoko ločljivo presevno elektronsko mikroskopijo (HRTEM) in z rentgensko difrakcijo. Ugotovljeno je, da kaljeno mikrostrukturo sestavljajo martenzit, zaostali avstenit in karbidi. Kriogena obdelava zmanjša delež zaostalega avstenita in povzroči povečano tetragonalnost martenzitne rešetke. Posledica je povečanje trdote za 2 HRc pred popuščanjem kriogeno obdelanega materiala, po popuščanju tega materiala pa je bila trdota za okrog 2,5 HRc nižja v primerjavi z jeklom brez kriogene obdelave. Na osnovi dejstva, da kriogeno obdelano jeklo vsebuje manj zaostalega avstenita in nepoznano količino nanoizločkov, pričakujemo njegovo manjšo zmožnost za pojav sekundarnega utrjevanjaTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije