Examination of Austenite Solidification and Spheroidal Graphite Growth in Ni-Fe-C Alloys

2015 ◽  
pp. 277-285 ◽  
Author(s):  
J. Qing ◽  
V. L. Richards ◽  
D. C. Van Aken
Keyword(s):  
Spheroidal Graphite ◽  
Graphite Growth

scholarly journals Revisiting Models for Spheroidal Graphite Growth

2018 ◽  
Vol 925 ◽  
pp. 118-124 ◽  
Author(s):  
Mathias Karsten Bjerre ◽  
Mohammed Azeem ◽  
Peter D. Lee ◽  
Jesper Henri Hattel ◽  
Niels Skat Tiedje
Keyword(s):  
Growth Rate ◽  
Cast Iron ◽  
Numerical Model ◽  
Final Stage ◽  
Nucleation And Growth ◽  
Ductile Cast Iron ◽  
Spheroidal Graphite ◽  
Microstructure Formation ◽  
X Ray ◽  
Graphite Growth

Recent experiments resolved nucleation and growth of graphite during solidification of ductile cast iron in 4D using synchrotron X-ray tomography. A numerical model for microstructure formation during solidification is compared with the experiments. Despite very good overall agreement between observations of spheroidal graphite growth and model results, significant deviations exist towards the end of solidification. We use the experimental observations to analyse the relation between graphite growth rate and the state of the particle neighbourhood to pinpoint possible links between growth rate of individual graphite spheres and the overall solidification state. With this insight we revisit existing models for growth of spheroidal graphite and discuss possible modifications in order to correctly describe the critical final stage of solidification.

scholarly journals Redistribution and Effect of Various Elements on the Morphology of Primary Graphite in Cast Iron

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
J. Lacaze ◽  
N. Valle ◽  
K. Theuwissen ◽  
J. Sertucha ◽  
B. El Adib ◽  
...  
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Spheroidal Graphite ◽  
Metallic Elements ◽  
Controlled Cooling ◽  
Cast Irons ◽  
Bulk Graphite ◽  
Distribution Of Elements ◽  
Graphite Growth ◽  
Secondary Ion

It has been shown repeatedly that many elements present as traces or at low level can affect graphite shape in cast irons. As part of a long term project aimed at clarifying the growth and the alteration of spheroidal graphite, a study on the effect of a few elements (Cu, Sn, Sb, and Ti) on primary graphite growth was undertaken and analysed with reference to an alloy without any such additions. This work was performed by remelting alloys in graphite crucibles thus saturating the melt in carbon and enabling primary graphite to grow by controlled cooling of the melt above the eutectic temperature. Primary graphite growth in the reference alloy was observed to be lamellar, while the added elements were found to affect bulk graphite and to modify its outer shape, with Sb leading eventually to rounded agglomerates together with wavy lamellae. Secondary ion mass spectrometry was used to analyze the distribution of elements, and no build-up of trace elements at the graphite surface could be observed. Instead, it is established that the perturbation of bulk graphite is associated with inhomogeneous distribution of metallic elements inside graphite precipitates.

scholarly journals Crystallography of Growth Blocks in Spheroidal Graphite

2018 ◽  
Vol 925 ◽  
pp. 54-61 ◽  
Author(s):  
Etienne Brodu ◽  
Emmanuel Bouzy ◽  
Jean Jacques Fundenberger ◽  
Benoit Beausir ◽  
Lydia Laffont ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Electron Backscatter Diffraction ◽  
Spheroidal Graphite ◽  
Transmission Electron ◽  
Competition Process ◽  
Graphite Growth ◽  
Scanning Electron

A better understanding of spheroidal graphite growth is expected in a near future thanks to widespread use of transmission electron microscopy. However, common transmission electron microscopy is quite time consuming and new indexing techniques are being developed, among them is transmission Kikuchi diffraction in a scanning electron microscope, a recent technique derived from electron backscatter diffraction. In the present work, on-axis transmission Kikuchi diffraction in scanning electron microscope, completed by transmission electron microscopy, was used with the objective of producing new observations on the microstructure of spheroidal graphite. This study shows that disorientations between blocks and sectors in spheroidal graphite are quite large in the early growth stage, which may be indicative of a competition process selecting the best orientations for achieving radial growth along thecdirection of graphite.

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.

Examination of Spheroidal Graphite Growth and Austenite Solidification in Ductile Iron

2016 ◽  
Vol 47 (12) ◽  
pp. 6197-6213 ◽  
Author(s):  
Jingjing Qing ◽  
Von L. Richards ◽  
David C. Van Aken
Keyword(s):  
Ductile Iron ◽  
Spheroidal Graphite ◽  
Graphite Growth

MEEHANITE GB300

Alloy Digest ◽  
2020 ◽  
Vol 69 (11) ◽  
Keyword(s):  
Thermal Conductivity ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Gray Cast Iron ◽  
High Strength ◽  
Heat Treating ◽  
Spheroidal Graphite ◽  
Cast Irons ◽  
Test Pieces ◽  
Temperature Performance

Abstract Meehanite GB300 is a pearlitic gray cast iron that has a minimum tensile strength of 300 MPa (44 ksi), when determined on test pieces machined from separately cast, 30 mm (1.2 in.) diameter test bars. This grade exhibits high strength while still maintaining good thermal conductivity and good machinability. It is generally used for applications where the thermal conductivity requirements preclude the use of other higher-strength materials, such as spheroidal graphite cast irons, which have inferior thermal properties. This datasheet provides information on physical properties, hardness, tensile properties, and compressive strength as well as fatigue. It also includes information on low and high temperature performance as well as heat treating, machining, and joining. Filing Code: CI-75. Producer or source: Meehanite Metal Corporation.

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