Numerická a experimentální analyza chemické heterogenity tuhnoucího těžkého válce z tvárné litiny

Numerical and experimental analysis of chemical heterogeneity of solidifying heavy ductile cast iron roller

článek v časopise - ostatní, Jost

en

The quality of the working rollers used for rolling rails is determined by the chemical and structural composition of the material of the rollers and the production technology. It is necessary to cast rollers with significantly improved utility properties, mainly high wear-resistance and optimal mechanical and structural properties. It is therefore necessary to find and ensure optimal relationships between the matrix structure and the resultant values of the mechanical properties of the rollers in order to maximize the length of life. The requirements introduced here cannot be ensured without knowledge of the kinetics of the solidification. Therefore numerical and experimental investigation of temperature field of the solidifying roller was conducted. The kinetics of the solidification has a measurable and non negligible influence on the chemical and structural heterogeneity of the investigated type of ductile cast iron. Tying on to the results of the model of the temperature field of the cast rollers, an original methodology was developed for the measurement of chemical microheterogeneity. The structure of this cast-iron is created by a great amount of the transition form of graphite and small amount of globular graphite and also lamellar graphite and cementite, whereas the structure of the metal matrix is perlitic. The volume amounts of the structural components were determined using the quantitative metallographic analysis, according to which the places for the analysis of the element composition using X ray energy dispersive spectral microanalysis were selected. The chemical and structural heterogeneity of the cast roller is therefore a significant function of the method of melting, modification and inoculation and the successive procedures of risering, casting and crystallization after cooling.

Kvalita pracovních válců pro válcovácí tratě různých profilů je určena chemickým a strukturálním složením materiálu válců a výrobní technologií. Je nutné nalézt optimální závislost mezi strukturou materiálu a výslednými mechanickými vlastnostmi válců s ohledem na maximalizaci životnosti, což vyžaduje znalost kinetiky tuhnutí. Byl proto proveden numerický a experimentální výzkum teplotního pole tuhnoucího válce. V návaznosti na výsledky modelu teplotního pole byl sestaven a aplikován model měření chemické heterogenity. Vybrané vzorky válce byly podrobeny kvantitativní metalografické analýze pro stanovení objemového složení strukturálních komponentů.

The quality of the working rollers used for rolling rails is determined by the chemical and structural composition of the material of the rollers and the production technology. It is necessary to cast rollers with significantly improved utility properties, mainly high wear-resistance and optimal mechanical and structural properties. It is therefore necessary to find and ensure optimal relationships between the matrix structure and the resultant values of the mechanical properties of the rollers in order to maximize the length of life. The requirements introduced here cannot be ensured without knowledge of the kinetics of the solidification. Therefore numerical and experimental investigation of temperature field of the solidifying roller was conducted. The kinetics of the solidification has a measurable and non negligible influence on the chemical and structural heterogeneity of the investigated type of ductile cast iron. Tying on to the results of the model of the temperature field of the cast rollers, an original methodology was developed for the measurement of chemical microheterogeneity. The structure of this cast-iron is created by a great amount of the transition form of graphite and small amount of globular graphite and also lamellar graphite and cementite, whereas the structure of the metal matrix is perlitic. The volume amounts of the structural components were determined using the quantitative metallographic analysis, according to which the places for the analysis of the element composition using X ray energy dispersive spectral microanalysis were selected. The chemical and structural heterogeneity of the cast roller is therefore a significant function of the method of melting, modification and inoculation and the successive procedures of risering, casting and crystallization after cooling.

Tvárná litina, válec, tuhnutí, chemická a strukturální heterogenita, metoda měření

Ductile cast iron, roller, solidification, chemical and structural heterogeneity, methodology for measurement

2012

18.06.2012

Ljubljana. Slovenia

1580-2949

46 (1912)

4

389–392

4