Metalurgické aspekty výroby vysocelegovaných duplexních a superduplexních ocelí

Abstract

The presented work begins with a description of the history of the development and production of the duplex steels. It is followed by a division of the duplex steels in the terms of a structure and chemical composition of the duplex, super duplex and hyper-duplex steels. The main content of the work is duplex steel which has its ideal phase content about 70 % of austenitic phase and 30 % of ferritic phase. There is also described the main effect of the alloying elements, namely chromium, nickel, molybdenum and nitrogen. The method of a steel resistance is also demonstrated to mention the relationship with PRE. The duplex steels belong to a group of stainless steels that exceed in a high resistance to corrosion. Its usage occurs in a strong oxidizing environment but it especially applies in the corrosive chloride environments. Consequently the work is focused on the important part like is the methods of the production of the duplex steels which are for the different metallurgical units mentioned in the conclusion of the work. Accordingly, the practical method of the processing steel of the melt duplex stainless steel, decarburization and application high nitrogen for individual units of AOD, VOD, EOP are theoretically described and the literature sources which supported the author's arguments are mentioned at the end of the work. The author tried to express the view that focused on the topic: If the selected major Czech steel companies are able to produce these steel and considered what chance they have to enforce them in the common crowded market.