Metalografické parametry oceli pro extrémní podmínky

Abstract

Thesis deals with evaluation of microstructural parameters of 34CrMo4 and 46Mn5 steels. The first part is orientated to problems of defects and microstructure of the 34CrMo4 steel. As this material is applied for pressure bottle production part of thesis describes two the most used production modes. Experimental part is focused on determination of non-metallic inclusions, banding, mean austenite grain size, segregations and shrinkages in rolling directions. Totally, specimens from ten different heats were analysed. For evaluation a comparative etalons and a computer technology were used. Results demonstrated that in diameter square billets from the 34CrMo4 steel are susceptible to banding and liquation. In steel 46Mn5 none microstructural banding was detected. In case of all studied specimens, inclusions of the D type represented the highest portion of impurities. In central areas of billets the highest level of non-metallic inclusion occurrence was found.