scholarly journals X-Ray Imaging of Formation and Growth of Spheroidal Graphite in Ductile Cast Iron

2018 ◽  
Vol 925 ◽  
pp. 104-109 ◽  
Author(s):  
Hideyuki Yasuda ◽  
A. Sugiyama ◽  
C. Kiattisaksri ◽  
Kohei Morishita ◽  
Tomoya Nagira ◽  
...  
Keyword(s):  
Cast Iron ◽  
Eutectic Growth ◽  
Ductile Cast Iron ◽  
Eutectic Solidification ◽  
Spheroidal Graphite ◽  
In Situ Observation ◽  
X Rays ◽  
Graphite Particles ◽  
Specimen Holder

Time-resolved and in-situ observations using synchrotron radiation X-rays were performed to observe solidification of cast iron (CE=4.5, 0.02mass%Mg). Morphology of graphite particles was influenced by specimen holder material. In the Al2O3 holder, graphite particles were spheroidal at the beginning and then deviated from the spheroidal shape. In addition, the coupled eutectic solidification of austenite and graphite occurred at the final stage. In contrast, the divorced eutectic solidification, in which graphite particles and austenite dendrites independently grew, was selected until the end of solidification in MgO holder. Spheroidal graphite particles were engulfed by austenite. Consequently, typical microstructure observed in ductile cast iron was reproduced in the in-situ observation. The results suggested that oxygen potential, which was determined by Al2O3 or MgO (specimen holder) in the observations, could be an important factor for the selection of eutectic growth mode and graphite morphology.

Nucleation and growth of graphite particles in ductile cast iron

2019 ◽  
Vol 775 ◽  
pp. 1230-1234 ◽  
Author(s):  
André de Albuquerque Vicente ◽  
João Roberto Sartori Moreno ◽  
Tiago Felipe de Abreu Santos ◽  
Denise Crocce Romano Espinosa ◽  
Jorge Alberto Soares Tenório
Keyword(s):  
Cast Iron ◽  
Nucleation And Growth ◽  
Ductile Cast Iron ◽  
Graphite Particles

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.

TEM Observation of Spheroidal Graphite in Ductile Cast Iron

PRICM ◽  
2013 ◽  
pp. 3459-3464
Author(s):  
Takamichi Hara ◽  
Takahiro Kitagawa ◽  
Susumu Ikeno ◽  
Seiji Saikawa ◽  
Kiyoshi Terayama ◽  
...  
Keyword(s):  
Cast Iron ◽  
Ductile Cast Iron ◽  
Spheroidal Graphite

Joint Strength and its Improvement of Friction Welded Joint Between Ductile Cast Iron and 5052 Al Alloy

2020 ◽  
Author(s):  
Masaaki Kimura ◽  
Akira Yoneda ◽  
Masahiro Kusaka ◽  
Koichi Kaizu ◽  
Kazuhiro Hayashida ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Cast Iron ◽  
Base Metal ◽  
Joint Strength ◽  
Welded Joint ◽  
Weld Interface ◽  
Ductile Cast Iron ◽  
Al Alloy ◽  
High Tensile Strength ◽  
Graphite Particles

Abstract To obtain dissimilar joint for easily making multi-material structures, the characteristics of friction welded joint between ductile cast iron (FCD400) and 5052 Al alloy (A5052) was investigated. The relatively high tensile strength of joint was obtained when that was made with a friction speed of 27.5 s−1, a friction pressure of 20 MPa, a friction time of 1.5 s, and a forge pressure of 270 MPa, respectively. However, this joint had approximately 77% in the tensile strength of the A5052 base metal and that was fractured at the weld interface. Although the weld interface had no intermetallic compound layer, the fractured surface at the A5052 side had some graphite particles that were supplied from the FCD400 side. To improve the joint strength, the graphite particles were reduced from the weld faying surface at the FCD400 side by decarburization treatment. The joint had approximately 96% in the tensile strength of the A5052 base metal and that was fractured between the A5052 side and the weld interface. The joint with high tensile strength as well as the possibility improving the fractured point of that were obtained when those were made with opportune friction welding condition and no graphite particles at the weld faying surface of the FCD400 side.

scholarly journals On the Primary Solidification of Compacted Graphite Iron: Microstructure Evolution during Isothermal Coarsening

2018 ◽  
Vol 925 ◽  
pp. 90-97 ◽  
Author(s):  
Juan Carlos Hernando ◽  
Attila Diószegi
Keyword(s):  
Cast Iron ◽  
Morphological Evolution ◽  
Solidification Process ◽  
Primary Phase ◽  
Eutectic Solidification ◽  
Spheroidal Graphite ◽  
Cube Root ◽  
Compacted Graphite ◽  
Primary Austenite ◽  
Graphite Cast Iron

It is widely accepted that in most commercial hypoeutectic alloys, both static mechanical properties and feeding characteristics during solidification, are extremely linked to the coarseness of the primary phase. It is therefore of critical importance to provide tools to control and predict the coarsening process of the dendritic phase present in hypoeutectic melts. The characterization of the primary phase, a product of the primary solidification, has traditionally been neglected when compared to the eutectic solidification characterization in cast iron investigations. This work presents the morphological evolution of the primary austenite present in a hypoeutectic compacted graphite cast iron (CGI) under isothermal conditions. To that purpose, a base spheroidal graphite cast iron (SGI) material with high Mg content is re-melted in a controlled atmosphere and reversed into a CGI melt by controlling the Mg fading. An experimental isothermal profile is applied to the solidification process of the experimental alloy to promote an isothermal coarsening process of the primary austenite dendrite network during solid and liquid coexistence. Through interrupted solidification experiments, the primary austenite is preserved and observed at room temperature. By application of stereological relations, the primary phase and its isothermal coarsening process are characterized as a function of the coarsening time applied. The microstructural evolution observed in the primary austenite in CGI and the measured morphological parameters show a similar trend to that observed for lamellar graphite cast iron (LGI) in previous investigations. The modulus of the primary austenite, Mγ, and the nearest distance between the centre of gravity of neighbouring austenite particles, Dγ, followed a linear relation with the cube root of coarsening time.

scholarly journals Primary Structure and Graphite Nodules in Thin-Walled High-Nickel Ductile Iron Castings

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 649
Author(s):  
Marcin Górny ◽  
Magdalena Kawalec ◽  
Gabriela Sikora ◽  
Ewa Olejnik ◽  
Hugo Lopez
Keyword(s):  
Cast Iron ◽  
Ductile Iron ◽  
Structural Features ◽  
Eutectic Solidification ◽  
Spheroidal Graphite ◽  
Quality Factors ◽  
Iron Castings ◽  
Spheroidal Graphite Cast Iron ◽  
Graphite Cast Iron ◽  
Thin Walled

This paper considers the most important quality factors in processing spheroidal graphite cast iron; namely, primary grains and graphite nodules in thin-walled ductile iron castings (TWDI). In the present study, the effect of grain refinement (by means of Ti, Nb and Zr) and of the holding time after spheroidization and inoculation on effecting the primary grains and eutectic structure in TWDI castings was investigated. Moreover, metallographic examinations (including electron backscattering diffraction, EBSD) were carried out to reveal the macro- and micro-structural features during the primary and eutectic solidification of the cast iron. EBSD results indicate that, within a single dendritic grain, there are numerous boundaries that split the grain into numerous smaller areas. In particular, it is found that the graphite nodules are in contact with the boundaries inside the primary dendritic grain. In turn, crystallization of highly branched dendrites is observed, which seems to “push” the graphite nodules into the interdendritic regions during their growth. The present work investigates the dominant mechanism that gives rise to the primary spheroidal graphite cast iron (SGI) structure. In addition, this work shows that the melt quality is closely associated with the resultant morphology and number of austenite dendrites, graphite nodules, and matrix structure.

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