Poliakova N. Influence of fase and structure composition on exploitation properties of high-chromium iron

Thesis is devoted to increasing of durability of white high-chromium cast irons for rolling mill rolls, working in shock-and-abrasive and corrosion-aggressive deterioration conditions. High-chromium cast iron is used for rolling mill rolls production. In hot rolling processes tool’s failure can be result from the combination of thermo-mechanical and chemical damage. A better knowledge of the oxidation, thermal fatigue, wear and corrosion destruction mechanisms in this material could be useful for a better appreciation of its service behaviour and lifetime. The high-temperature oxidation of white high-chromium cast iron in different structures states in temperature range 150 - 680 °C was studied. The growth of oxide films on surface of experimental specimens and their composition was investigated. The influence of heating and cooling conditions on structure and properties high chromium cast iron was investigated. The tendency of white cast iron to thermal fatigue damage was shown. Peculiarities of thermal cracks nucleation and growth were studied. Experimental results confirmed that previous high temperature influence promotes and accelerates abrasive wear of high chromium cast iron. The corrosion resistance of white cast iron in electric-conductive mediums was investigated. The effects of structural condition and surface roughness of white high chromium iron on the peculiarities corrosion degradation resistance were investigated.