Nucleation and growth of graphite particles in ductile cast iron

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.

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

JSME 2020 Conference on Leading Edge Manufacturing/Materials and Processing ◽

10.1115/lemp2020-8513 ◽

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.

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The Effect of Magnesium to Sulfur Ratio on the Graphite Morphology of Graphite Cast Iron Produced at Differrent Section Thicknesses

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.383-390.5880 ◽

2011 ◽

Vol 383-390 ◽

pp. 5880-5885

Author(s):

Omar Elmabrouk ◽

Osama M. Erfan ◽

Ali Kalkanli

Keyword(s):

Mechanical Properties ◽

Cast Iron ◽

Ductile Cast Iron ◽

Flake Graphite ◽

Factors Affecting ◽

Compacted Graphite ◽

Graphite Particles ◽

Graphite Morphology ◽

Graphite Cast Iron ◽

Flake Graphite Cast Iron

This paper is concerned with the investigation of the effect of magnesium to sulfur ratio on the graphite morphology and estimation of the ranges of this ratio use to produce graphite cast iron at different section sections. The main factors affecting shape of graphite cast iron are the metallurgical structures and the section thicknesses. Cast iron of different shapes of graphite particles directly affect its thermo-mechanical properties. The nodular shape of these graphite particles such as in ductile cast iron improve its mechanical properties, on the other hand, when the shape of these graphite particles become elongated such as in flake graphite cast iron results in improving its thermal conductivity. In between, the worm-like shape of these graphite particles such as in compacted graphite cast iron, make this type of cast iron to have thermo-mechanical properties in between those of ductile and flake graphite cast iron. The different types of ductile , compacted and flake graphite cast iron were produced by means of plunger method at different section thicknesses and the effect of Mg/S ratio on these types of graphite particles was investigated and its range was established.

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

Materials Science Forum ◽

10.4028/www.scientific.net/msf.925.104 ◽

2018 ◽

Vol 925 ◽

pp. 104-109 ◽

Cited By ~ 2

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.

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