15 KB533 KB14 KB200020242012Dobrovská, JanaGontarev, VasilijKavička, FrantišekSekanina, BuhumilStransky, Karelštevilka:4letnik:46str. 389-392ISSN:1580-2949COBISSID:937642URN:URN:NBN:SI:doc-XQU6KY9ZenInštitut za kovinske materiale in tehnologijeMateriali in tehnologijechemical and structural heterogeneitykemijska in strukturna heterogenostmethodology for measurementmetodologija meritevrollersiva litina s kroglastim grafitomsolidificationspheroidal graphite cast ironstrjevanjevaljNumerical and experimental analyses of the chemical heterogeneity of a solidifying heavy ductile-cast-iron roller| Numerična in eksperimentalna analiza kemijske heterogenosti strjevanja litega težko gnetljivega železnega valja|The quality of the working rollers used for rolling rails is determined by the chemical and structural compositions of the material of the rollers and the production technology. It is necessary to cast rollers with significantly improved utility properties, i.e., mainly a high wear resistance and optimal mechanical and structural properties. It is, therefore, necessary to find and ensure the optimal relationships between the matrix structure and the resulting values of the mechanical properties of the rollers in order to maximize their life time. The requirements introduced here cannot be ensured without a knowledge of the kinetics of the solidification. Therefore, numerical and experimental investigations of the temperature field of the solidifying roller were conducted. The kinetics of the solidification has a measurable and non-negligible influence on the chemical and structural heterogeneity of the investigated type of ductile cast-iron. Linking to the results of the model of the temperature field of the cast rollers, an original methodology was developed for the measurement of chemical micro-heterogeneity. The structure of this cast-iron is created by a large amount of the transition form of graphite and a small amount of globular graphite, and also the lamellar graphite and cementite, whereas the structure of the metal matrix is perlitic. The volume amounts of the structural components were determined using a quantitative metallographic analysis, according to which the places for the analysis of the element composition using X-ray energy-dispersive spectral micro-analysis were selected. The chemical and structural heterogeneity of the cast roller is, therefore, a significant function of the method of melting, modification and inoculation and the successive procedures of risering, casting and crystallization after coolingKakovost delovnih valjev za valjanje tirnic je določena s kemijsko in strukturno sestavo materiala za valje in s tehnologijo proizvodnje. Potrebno je ulivati valje z znatno povečanimi koristnimi lastnostmi, kot so obrabna odpornost in optimalne mehanske in strukturne lastnosti. Tako je treba ugotoviti in zagotoviti optimalne odnose med strukturo matrice in rezultirajočimi vrednostmi mehanskih lastnosti valjev za maksimiranje trajnostne dobe. Zahteve, ki so tu predstavljene, ne morejo biti zagotovljene brez znanja kinetike strjevanja. Zato je bila vpeljana numerična in eksperimentalna raziskava temperaturnega polja valja pri strjevanju. Kinetika strjevanja ima merljiv in ne brezpomemben vpliv na kemijsko in strukturno heterogenost raziskovanega gnetljivega litega železa. Glede na rezultate modela temperaturnega polja ulitih valjev je bila razvita originalna metodologija za merjenje kemijske mikroheterogenosti. Struktura tega ulitega železa je bila ustvarjena z veliko količino prehodnih oblik grafita in manjših količin kroglastega grafita in cementita, medtem ko je struktura kovinske osnove perlitna. Volumenska količina strukturnih komponent je bila določena s kvantitativno metalografsko analizo, po kateri so bila izbrana mesta za rentgensko analizo sestave ter spektrografsko mikroanalizo. Kemijska in strukturna heterogenost ulitih valjev je pomembna funkcija pri taljenju in modificiranju ter za uspešno ulivanje in kristalizacijo po ohlajevanjuTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije