Temperature Field and Solidification Structure of a Ductile-Cast-Iron Roller

2013 ◽  
Vol 592-593 ◽  
pp. 197-200
Author(s):  
František Kavička ◽  
Jana Dobrovská ◽  
Karel Stránský ◽  
Bohumil Sekanina ◽  
Josef Stetina
Keyword(s):  
Temperature Field ◽  
Cast Iron ◽  
Structural Heterogeneity ◽  
Ductile Cast Iron ◽  
Solidification Structure ◽  
Heat Flows ◽  
Working Rollers ◽  
Original Application ◽  
Kinetics Of

The quality of the working rollers from ductile-cast-iron used for rolling rails is determined by the chemical and structural composition of the material of the rollers and the production technology. The requirements of the quality cannot be ensured without perfect knowledge of the course of solidification, cooling and heat treatment of the cast rollers as well as the kinetics of the temperature field of the casting and mould. An original application of ANSYS simulated the forming of the temperature field of the entire system comprising the casting, the mold and ambient. In the experimental investigation of temperature field, an original methodology for the measurement of the distribution of temperatures and heat flows in the roller-mould system had been developed and verified in the operation. 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 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.

The Model of Temperature Field and Chemical Heterogeneity of Solidifying Ductile-Cast-Iron Roller

2011 ◽  
Author(s):  
Jana Dobrovska ◽  
Frantisek Kavicka ◽  
Karel Stransky ◽  
Bohumil Sekanina
Keyword(s):  
Temperature Field ◽  
Cast Iron ◽  
Structural Heterogeneity ◽  
Ductile Cast Iron ◽  
Chemical Heterogeneity ◽  
The Matrix ◽  
Working Rollers ◽  
Length Of Life ◽  
Kinetics Of

The quality of the working rollers used for rolling rails of different profiles is determined by the chemical and structural composition of the material of the rollers and the production technology. 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 perfect knowledge of the course of solidification, cooling and heat treatment of the cast rollers as well as the kinetics of the temperature field of the casting and mould. The kinetics of the solidification has a measurable and non-negligible influence on the chemical and structural heterogeneity of the investigated type of 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.

Cooling of a Massive Casting of Ductile Cast-Iron and Its Numerical Optimization

2009 ◽  
Author(s):  
Frantisek Kavicka ◽  
Karel Stransky ◽  
Bohumil Sekanina ◽  
Jana Dobrovska ◽  
Josef Stetina
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Temperature Field ◽  
Cast Iron ◽  
Numerical Optimization ◽  
Numerical Models ◽  
Ductile Cast Iron ◽  
Chemical Heterogeneity ◽  
Numerical Finite Element ◽  
Original Application

The numerical models of the temperature field of solidifying castings often observe two main goals: directed solidification and optimization of the technology. These goals can be achieved only if the deciding factors which either characterize the process or accompany it are analysed and their influence controlled. An original application of ANSYS, based on the numerical finite-element method, is applied. The numerical model simulated the forming of the temperature field of a two-ton 500×500×1000 mm casting from ductile cast-iron during the application of various methods of its cooling using steel chills. This model managed to optimize more than one method of cooling but, in addition to that, provided results for the successive model of structural and chemical heterogeneity, and so it also contributes to influencing the pouring structure. The file containing the acquired results from both models, as well as from their organic unification, brings new and, simultaneously, remarkable findings of causal relationships between the structural and chemical heterogeneity and the local solidification time in any point of the casting. This has established a tool for the optimization of the structure with an even distribution of the spheroids of graphite in such a way so as to minimize the occurrence of degenerated shapes of graphite, which is one of the conditions for achieving good mechanical properties of castings of ductile cast-iron.

scholarly journals The Influence of Different Assist Gases on Ductile Cast Iron Cutting by CO2 Laser

2017 ◽  
Vol 17 (4) ◽  
pp. 109-114 ◽  
Author(s):  
J. Meško ◽  
R. Nigrovič ◽  
A. Zrak
Keyword(s):  
Cast Iron ◽  
Laser Cutting ◽  
Roughness Parameter ◽  
Cutting Speed ◽  
Nodular Cast Iron ◽  
Ductile Cast Iron ◽  
Engineering Practice ◽  
Technological Parameters ◽  
The Stability

Abstract This article deals with the technology and principles of the laser cutting of ductile cast iron. The properties of the CO2 laser beam, input parameters of the laser cutting, assist gases, the interaction of cut material and the stability of cutting process are described. The commonly used material (nodular cast iron - share of about 25% of all castings on the market) and the method of the laser cutting of that material, including the technological parameters that influence the cutting edge, are characterized. Next, the application and use of this method in mechanical engineering practice is described, focusing on fixing and renovation of mechanical components such as removing the inflow gate from castings with the desired quality of the cut, without the further using of the chip machining technology. Experimental samples from the nodular cast iron were created by using different technological parameters of laser cutting. The heat affected zone (HAZ), its width, microstructure and roughness parameter Pt was monitored on the experimental samples (of thickness t = 13 mm). The technological parameters that were varied during the experiments included the type of assist gases (N2 and O2), to be more specific the ratio of gases, and the cutting speed, which ranged from 1.6 m/min to 0.32 m/min. Both parameters were changed until the desired properties were achieved.

Time Evolution of Solidification Structure in Ductile Cast Iron with Hypereutectic Compositions

2020 ◽  
Vol 14 (3) ◽  
pp. 794-801
Author(s):  
Kiattisaksri Chatcharit ◽  
Akira Sugiyama ◽  
Kohei Morishita ◽  
Taka Narumi ◽  
Kentaro Kajiwara ◽  
...  
Keyword(s):  
Cast Iron ◽  
Time Evolution ◽  
Ductile Cast Iron ◽  
Solidification Structure

scholarly journals Prospects for using boron in metallurgy. Report 1

2021 ◽  
Vol 64 (7) ◽  
pp. 471-476
Author(s):  
V. I. Zhuchkov ◽  
O. V. Zayakin ◽  
A. A. Akberdin
Keyword(s):  
Cast Iron ◽  
Boron Oxide ◽  
Sulfur Removal ◽  
Steel Production ◽  
Liquid Phase Sintering ◽  
Blast Furnace Smelting ◽  
Technical And Economic Indicators ◽  
Kinetics Of ◽  
Metallurgical Processes

On the basis of literature and our own data, the effect of boron on characteristics of all stages of metallurgical processes (from sintering, smelting of cast iron and ferroalloys, to steel production) and on the properties of the resulting slag and metal was studied. To intensify the pellets hardening at the stage of liquid-phase sintering and to improve their metallurgical properties, it is sufficient to have 0.20 – 0.35 % of boron oxide in them. According to the laboratory studies, the presence of boron oxide in pellets increases their compressive strength by 1.5 – 1.7 times and hot strength by 3 – 4 times. While studying the mechanism and kinetics of sulfur removal, it was shown that the presence of boric anhydride significantly intensifies processes of pellets desulfurization. Their intensive progress goes to the zones of lower temperatures of 1050 – 1100 °С. To increase the sinter strength characteristics, it is possible to add B2O3 to the charge. The introduction of 0.44 % of B2O3 does not affect the sinter abrasion. The content of fines (0 – 5 mm) in comparison with the base sample is reduced by 1.5 times. The use of boron pellets in blast-furnace smelting makes it possible to increase the basicity of the final slag from 1.10 to 1.16. In this regard, the sulfur distribution coefficient increases from 48 to 74. The sulfur content in cast iron decreases by 0.005 %. The possibility of using boron and its compounds to improve the technical and economic indicators of production and the quality of pellets, sinter and cast iron is shown on the base of the presented theoretical, laboratory-experimental and industrial data.

The Character of the Solidification Structure of Massive Ductile Cast-Iron Castings and its Prediction

2007 ◽  
Vol 567-568 ◽  
pp. 109-112
Author(s):  
Karel Stránský ◽  
Jana Dobrovská ◽  
František Kavička ◽  
Josef Stetina ◽  
Bohumil Sekanina ◽  
...  
Keyword(s):  
Cast Iron ◽  
Three Dimensional ◽  
Calculated Data ◽  
Ductile Cast Iron ◽  
Solidification Time ◽  
Solidification Structure ◽  
Local Solidification Time ◽  
Iron Castings ◽  
Basic Characteristics ◽  
Average Size

An original three-dimensional (3D) model of solidification is used to describe the process of solidification and cooling of massive 500x1000x500 mm cast-iron castings in sand moulds. The calculated model of the kinetics of the temperature field of the casting is verified during casting with temperature measurements in selected points. The following dependences are later determined according to the experimental and calculated data: the average size of the graphite spheroids rg, graphite cells Rb and the average distances among the particles of graphite Lg – always as a function of the local solidification time θ [xi, yi, zi]. Furthermore, it has been found that the given basic characteristics of the structure of the cast-iron (rg, Rb and Lg) are a linear function of the logarithm of the local solidification time θ. The original spatial model of solidification can therefore be used in its first approximation for the assessment of the pouring structure of massive cast-iron castings.

Kinetics of Coarsening and Solid Sphericity during Reheating of Ductile Iron and Al Alloys

2006 ◽  
Vol 116-117 ◽  
pp. 205-208 ◽  
Author(s):  
P. Babaghorbani ◽  
S. Salarfar ◽  
Mahmoud Nili-Ahmadabadi
Keyword(s):  
Cast Iron ◽  
Solid State ◽  
Ostwald Ripening ◽  
Ductile Cast Iron ◽  
Al Alloys ◽  
Solid Particles ◽  
Coarsening Kinetics ◽  
Semi Solid ◽  
Reheating Process ◽  
Kinetics Of

Reheating process in the semi-solid state is a very important step in the thixoforming process. In this research semi-solid ductile cast iron and Al alloys (Al-2.5Si, Al356) prepared by inclined plate method, were reheated to examine the effect of reheating conditions on the microstructure and coarsening kinetics of the alloys. For ductile cast iron, solid fraction at different reheating temperatures and holding times was obtained and based on these results the optimum reheating temperature range was determined. In the case of Al alloys increase of holding time in the semi-solid state, leads to increase of liquid fraction, solid grain size and improvement of sphericity of solid particles. In addition, the results show that coarsening kinetics of microstructures of both alloys during reheating was diffusion controlled and can be mostly treated by Ostwald ripening theory.

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