Using of phase transformations in the eutectic carbides for increase in plasticity by steels and cast

T. M. Myronova

Abstract


Raising of problem. Studying of phase transformations is into the carbides of rapid tool steel and white cast-iron for structure changes in their eutectic constituent namely in disturbing of monolithic structure of ledeburite colonies cementite structure and eutectic net continuity. Also the mentioned heat treatment modes are targeted to the eutectic net shift for the most suitable position from the point of plastic deforming. Materials and methodology of researches. The hypoeutectic rapid tool steels and white cast irons with 2,92…3,35 % carbon content and additionally alloyed by chrome, molybdenum, tungsten vanadium have been used as the research materials. The mentioned alloys have been pre-heat treated at a temperature 1 000…1 220 ˚С and hot twist tested. Information about structural and phase changes was got the methods of optical and electronic microscopy, by "Axiomat" and "JSM−35". Micro x-ray photography spectral a x-ray structural analysis was conducted by means of analyzer "САМЕBАCS" and «ДРОН−3,0 УМ». Research Results. The research results showed that the under the alloying of iron-carbon alloys by carbide forming elements the eutectics form in their structure. The mentioned eutectics are based on complex composition metastable carbides. The phase transformations which are targeted to the shifting to stable state take place in complex composition metastable carbides under the heat impact. Such shifts could be relative divided into two types. The first one is metastable carbides transformation into stable ones. The second type is the breakdown of carbide based supersaturated solid solutions. The carbide class alloys plasticity in most cases depends from eutectic constituent behavior during deformation process and mainly from structure and phase transformations in brittle carbides. Practical significance The use the effect of дактилирования in the economy alloyed white cast-iron did possible treatment pressure pilot-scale, for example malleable or rolling. Conclusions. The formation of sub-grain and inter-phase borders simplifies brittle carbides breakdown under deformation. However the phase transformations stage of completion and nature of formed phase’s borders significantly influence the carbide behavior during deformation. The article is represented that the excessive vanadium carbides precipitation from supersaturated iron carbide in white cast irons intensifies directly under hot deforming which is resulted in cementite plastic flow and cast iron plasticity increasing.


Keywords


metastable carbides; phase transformations; hot deforming; steels of carbide class; white cast irons; plasticity increasing

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