Podmínky rozpouštění modifikátoru na bázi hořčíku při modifikaci metodou FLOTRET

Abstract

Global casting production in 2008 dipped below 2007's production, dropping 1,5% to 93,5 million metric tons from 94,9 million metric tons. Portion of the castings made from cast iron with spheroidal graphite was 22,87 % (23,8 mil. tons). In 2008, two hundred foundry plants in Czech Republic produced 536,8 thousand tons of castings and portion of castings from cast iron with spheroidal graphite from this amount was 9,7 % (52,15 thousand tons).

This doctoral thesis is focused on continual production’s methods of cast iron with spheroidal graphite and first of all it is focused on method FLOTRET. Increasing requirements on material properties useful for castings led to the implementing of cast iron with graphite in modified forms into the production, whereas required properties are obtained by changing of graphite’s shape, size and layout, and changing of metal basic structure.

Basic principles of the secondary treatment of cast irons, especially technology and physico-chemical principals of modifications and inoculations are summarized in the theoretical part of the thesis.

Practical part of the thesis is divided into laboratory and operation trials. Laboratory experiments were realized with using of laboratory modifier chambers FLOTRET type, which was designed and hydraulically optimized within the frame of thesis solution. Experiments were focused on effects of gravity head and modifier amount on value of residual magnesium as a condition of successful modification. In conditions of operation, the method was tested in five foundry plants and modification process was observed for a long time in one of them.

The doctoral thesis summarize gained results. On their basics it is possible to determine optimal parameters of modification process by FLOTRET method.