Parametry ovlivňující mikročistotu oceli v průběhu odplynění na vakuovací stanici RH

Abstract

This thesis is focused on parameters of degassing on the RH vacuum station and their influence on steel microcleanliness. The first part contains theoretical information on steel cleanliness and vacuum refining process as one of the most significant ways of secondary metallurgy to improve quality of steel. The aim of the next part is to analyze commonly used operating and dimension parameters of the RH vacuum station based on researches presented in foreign literature. In the RH vacuum process, melt circulation is regarded as the influential factor of the steel refining, and so it depends on both kinds of parameters. This is the reason why it is quite difficult to define the operating conditions for optimum melt circulation, therefore two variations of taking samples were made at the RH station no. 1 in TŽ, a.s. as the research part of the thesis. The obtained results were evaluated by ONH836 Oxygen Elemental Analyzer and by versatile tungsten thermionic emission SEM system. The measured data and generated charts were subsequently compared with theoretical knowledge, and the main finding reveals that a fundamental role regarding the final number of inclusions is played by the initial number of inclusions before RH treatment itself.