COMPUTATIONAL METHOD FOR DETERMINING TEMPERATURE DEPENDENCIES OF LINEAR EXPANSION COEFFICIENT OF CARBON ALLOYS

In modeling of shrinkage processes during solidification and  cooling billets on the continuous casting machine there is a need to  determine values of coefficient of linear expansion, depending on  temperature and carbon content. Experimental data to coefficients of  line ar expansion given in reference literature are in most cases limited to a low-temperature interval, the upper limit of which does not  exceed 1200  °C. The values of this coefficient are unknown for high  temperatures. Their calculation definition is carried out recently with  the use of empirical dependences for calculation of change of phases’  specific  volumes  at  temperature  changes.  However,  dependencies  given in the literature are often contradictory. In this regard there was  a need to develop a unified method for determining values of linear  expansion coeffi  cient depending on temperature and carbon content.  In derivation of formulas for calculation of linear shrinkage coefficient, the pre viously obtained expressions for calculation of specific  volumes of Fe – C alloys were taken as a base. Since the change in  specific volume with the temperature significantly affects carbon content, calculation of linear shrinkage coefficient is performed separately  for three intervals of carbon concentrations: 0  –  0.10  %, 0.10  –  0.16  %  and 0.16  –  0.50  %, differing from each other in various phase transformations during solidification and cooling of alloys. An example of  calculated determination of linear shrinkage coefficient is given for  the midpoints of specified intervals. Comparison of the obtained calculation results with known literature and reference data was made.  Adequa cy of the proposed technique was established and possibility of  its use for the research problems solving is shown.

linear shrinkage,  linear expansion coefficient,  specific volume,   Fe – C phase diagram

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