scholarly journals Metastable Eutectoid Transformation in Spheroidal Graphite Cast Iron: Modeling and Validation

Metals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 550 ◽  
Author(s):  
Fernando D. Carazo ◽  
Laura N. García ◽  
Diego J. Celentano
Keyword(s):  
Initial Conditions ◽  
Spheroidal Graphite ◽  
Eutectoid Transformation ◽  
Cast Irons ◽  
Spheroidal Graphite Cast Iron ◽  
Graphite Cast Iron ◽  
Proposed Model ◽  
Three Phase ◽  
Microstructural Model ◽  
Graphite Growth

This paper presents a new microstructural model of the metastable eutectoid transformation in spheroidal graphite cast irons. The model takes into account the nucleation and growth of pearlite nodules. The nucleation is assumed to be continuous and dependent on the metastable undercooling associated with the upper limit of the three-phase field, while the growth rate is considered to be ruled by the silicon partitioning between ferrite and cementite at the pearlite/austenite front. The initial conditions for the metastable transformation are obtained from a microstructural simulation of solidification, graphite growth, and stable eutectoid transformation. These microstructural models are coupled with the thermal balance solved at a macroscopic level via the finite element method. The experimental validation of the metastable eutectoid model achieved by comparison with measured values of ferrite, graphite, and pearlite fractions at the end of the cooling process demonstrates the sound predictive capabilities of the proposed model.

Semisolid Forging of Cast Iron Using Rapid Resistance Heating

2007 ◽  
Vol 561-565 ◽  
pp. 925-928 ◽  
Author(s):  
Seijiro Maki ◽  
Kazuhito Suzuki ◽  
Kenichiro Mori
Keyword(s):  
Cast Iron ◽  
Control Function ◽  
Electric Energy ◽  
Spheroidal Graphite ◽  
Pig Iron ◽  
Resistance Heating ◽  
Cast Irons ◽  
Ac Power ◽  
Spheroidal Graphite Cast Iron ◽  
Graphite Cast Iron

Feasibility of semisolid forging of cast iron using rapid resistance heating was experimentally investigated. Gray pig iron FC250 and spheroidal graphite cast iron FCD600, whose carbon equivalents are both 4.3% in mass, were used for the experiments. Since these cast irons have a narrow semisolid temperature range, an AC power supply with an input electric energy control function was used. In this study, the resistance heating characteristics of the cast irons were firstly examined, and then their semisolid forging experiments were conducted. In the forging experiments, the conditions of the forgings such as microstructures and hardness properties were examined, and the feasibility of the semisolid forging of cast iron using resistance heating was discussed. As a result, it was found that the method presented here is highly feasible.

Influence of Cooling Rate and Alloying Elements on Kinetics of Eutectoid Transformation in Spheroidal Graphite Cast Iron

2010 ◽  
Vol 457 ◽  
pp. 163-168 ◽  
Author(s):  
Primož Mrvar ◽  
Mitja Petrič ◽  
Jožef Medved
Keyword(s):  
Cast Iron ◽  
Cooling Rate ◽  
Alloying Elements ◽  
Spheroidal Graphite ◽  
Eutectoid Transformation ◽  
Spheroidal Graphite Cast Iron ◽  
Graphite Cast Iron ◽  
Short Time ◽  
Kinetics Of

Paper deals with influence of cooling rate and alloying elements on kinetics of eutectoid transformation in spheroidal graphite cast iron (SGI). Transformation of austenite can proceed into ferrite and graphite (FeFeG) and/or in pearlite (Fe  FeFe3C). Examination of eutectoid transformation was made by evaluating the “in-situ” dilatation curves together with metallographic examinations, DTA, and dilatation analyses in solid state. ThermoCalc software was applied for thermodynamic calculations of phase equilibria. Based on numerous quantitative relations, such as relation between fractions of ferrite and pearlite in the as-cast SGI that was determined by analysis of dilatometric curves and taking into account also composition of melt, ferrite/pearlite ratio in the microstructure could be determined in a very short time. Thus the melt composition could be corrected by adding Cu and/or Mn or Si, respectively, using the "in situ" dilatation analyses. Characteristic temperatures of eutectoid transformation have been established from the kinetics of austenite transformation and from temperature dependence of ferrite and/or pearlite growth. Kinetics curves that enable to determine fractions of single microstructure constituents in the microstructure as function of transformation time, mainly used for ferrite and pearlite SGI, can be well determined with physical sigmoidal Boltzmann model.

Study of the Eutectoid Transformation in the As-Cast Spheroidal Graphite Cast Iron with 'in Situ' Dilatation Analysis – Method for Quality Control

2006 ◽  
Vol 508 ◽  
pp. 287-294 ◽  
Author(s):  
Primož Mrvar ◽  
Milan Tribžan ◽  
Jožef Medved ◽  
Alojz Križman
Keyword(s):  
Cast Iron ◽  
Spheroidal Graphite ◽  
Eutectoid Transformation ◽  
Spheroidal Graphite Cast Iron ◽  
Graphite Cast Iron ◽  
Transformation Time ◽  
Short Time ◽  
Boltzmann Model ◽  
Ferrite Nucleation

The eutectoid transformation of the spheroidal graphite cast iron (S.G.I.) has been investigated with “in situ” dilatometer, which was made for the investigation of the cast iron alloys. The investigation of the eutectoid transformation has been taking place by evaluation of the “insitu” dilatation curves in connection with metallographic examinations, chemical analyses and thermodynamic calculations of the phase equilibriums. By dilatometric curves it is possible to follow the exact eutectoid transformation of austenite. On a basis of numerous quantitative relations, as the relation between the ferrite and pearlite fractions in the as-cast SGI, which was determined by the analysis of the dilatometric curves and the composition, the ratio between ferrite and pearlite in the microstructure could be determined in a very short time. From the kinetics of austenite transformation and temperature dependence of the ferrite or pearlite growth the following characteristic temperatures of the eutectoid transformation have been established: the ferrite nucleation o Tα , the beginning of the ferrite growth Tα , and pearlite growth Tp , respectively. Kinetic curves, which show the fraction of the single microstructure constituents in the microstructure in dependence of the transformation time for mainly ferrite SGI, are good represented by the physical sigmoidal Boltzmann model.

Experimental Investigation of Twist Fatigue Characteristics on Piston Rings

2020 ◽  
Vol 12 (2) ◽  
Author(s):  
E. Pavithra ◽  
Mahesh Dhakal ◽  
Prithvi Hada ◽  
N. Yuvaraj ◽  
K. Sridhar
Keyword(s):  
Cast Iron ◽  
Internal Combustion Engines ◽  
Piston Ring ◽  
Spheroidal Graphite ◽  
Piston Rings ◽  
Cast Irons ◽  
Spheroidal Graphite Cast Iron ◽  
Graphite Cast Iron ◽  
Grey Cast ◽  
Fatigue Characteristics

Piston ring is one of the most important parts of the internal combustion engines. This paper investigates the mechanical and twist fatigue characteristics on different piston ring materials. The piston ring materials were chosen in this study such as grey cast irons (3740 and 6140), malleable cast iron (3929), spheroidal graphite cast iron (6139) and martensitic carbidic grey cast iron (6454). Twist fatigue test was conducted on different materials of piston rings in order to identify the suitable piston ring for the effective operation. Geometrical features and the mechanical properties were also assessed in different materials for the effectiveness of piston rings.

Suppression of Elevated Temperature Brittleness in Spheroidal Graphite Cast Iron by Increasing Phosphorus Content

2010 ◽  
Vol 457 ◽  
pp. 428-432
Author(s):  
Yoshitaka Iwabuchi ◽  
Isao Kobayashi
Keyword(s):  
Cast Iron ◽  
Elevated Temperature ◽  
Phosphorus Content ◽  
Marked Decrease ◽  
Spheroidal Graphite ◽  
Cast Irons ◽  
Spheroidal Graphite Cast Iron ◽  
Graphite Cast Iron ◽  
Low Phosphorus ◽  
Fracture Appearance

Elevated temperature brittleness (ETB) of spheroidal graphite (s-g) cast iron has been referred to as reduced ductility within an elevated temperature range and has been related to grain boundary brittleness. The phenomenon of ETB has not been yet clearly understood. In this study, the factor affecting on ETB was studied in terms of strain rate and chemical composition. A study was carried out on the influence of phosphorus on ETB by using laboratory-made heats containing different phosphorus contents. ETB indicated the marked decrease in ductility at around 673K. S-g cast iron containing low phosphorus content manifested ETB at temperatures between 650K and 700K. There was a consistent correlation between the fractional increases in intergranular fracture appearance and the decrease in elongation. The increase of phosphorus suppressed ETB and s-g cast irons containing phosphorus exceeding 0.030 % were found to be immune to ETB. It was found that ETB could be suppressed by reducing the ratio of magnesium and phosphorus to less than 1.5.

The role of manganese and copper in the eutectoid transformation of spheroidal graphite cast iron

1997 ◽  
Vol 28 (10) ◽  
pp. 2015-2025 ◽  
Author(s):  
Aline Boudot ◽  
Valérie Gerval ◽  
Djar Oquab ◽  
Jacques Lacaze ◽  
Henrique Santos
Keyword(s):  
Cast Iron ◽  
Spheroidal Graphite ◽  
Eutectoid Transformation ◽  
Spheroidal Graphite Cast Iron ◽  
Graphite Cast Iron
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