Influence of intercritical austempering on the microstructure and mechanical properties of austempered ductile cast iron (ADI)

Panneerselvam, Saranya; Putatunda, Susil K.; Gundlach, Richard B.; Boileau, James

doi:10.1016/j.msea.2017.03.096

Cited by 66 publications

(49 citation statements)

References 18 publications

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“…Under this experimental procedure, the relative amounts and morphology of ferrite and ausferrite can be controlled by using different austenitizing temperatures and thermal cycles. The literature reports several experimental procedures and considerations to obtain IADI [2][3][4][5] and different mechanical properties based on the amount of ferrite and ausferrite [6][7][8]. In general, tensile strength, yield stress, and fracture toughness increase when the amount of ausferrite increases, while elongation diminishes.…”

Section: Introductionmentioning

confidence: 99%

Microstructural damage evaluation of ferritic-ausferritic spheroidal graphite cast iron

Fernandino

Cocco

Tenaglia

et al. 2019

Frattura Ed Integrità Strutturale

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The goal of this work is to improve the understanding of the relation between the microstructural characteristics of Intercritical Austempered Ductile Cast Iron (IADI) and the damage micromechanisms observed during its tensile loading. The experimental methodology involves heat treatments to obtain IADI and the assessment of the damage mechanisms (sequence and occurrence) during step by step tensile testing. The damage evaluation was carried out by observing the surface of the tensile test specimen with optical and scanning electron microscopy. The results show that small cracks start forming soon after the yield stress is surpassed. The crack initiation is preferentially located at matrix-nodule interface. As loading increases, cracks also develop at the ferritic grain boundaries and the ausferritic/ferritic interfaces. Consequently, at higher strain values, a competition between the plastic deformation on internodular zones and crack propagation along ausferritic phase is observed. Finally, the final fracture is produced by the propagation of cracks across the internodular ligaments and through the ausferritic/ferritic interface that later coalesce into a single dominant crack leading to the material failure.

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Section: Introductionmentioning

confidence: 99%

Microstructural damage evaluation of ferritic-ausferritic spheroidal graphite cast iron

Fernandino

Cocco

Tenaglia

et al. 2019

Frattura Ed Integrità Strutturale

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“…Cleavage fracture changes its direction when crossing the intergranular fracture and graphite nodules, similar to a river pattern [26]. Cleavage fracture generally occurred in high microstructure strength (with low plasticity) and tended to take place in the inclusion around the eutectic cell boundary rather than in the distance between nodular interfaces [27]. Figure 3 shows that the stance between the nodule and the hollow at 4.5 mm/s speed is relatively small and plentiful compared to that at 1.5 mm/s.…”

Section: The Description Of Tensile Test Resultsmentioning

confidence: 88%

Crosshead Speed Effects on Ferro Casting Ductile (Fcd) Tensile Strength and Fault Morphology

Andoko¹

2019

MM SJ

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Nodular cast iron or Ferro casting ductile (FCD) is the developmental result of grey cast iron. Nodular cast iron has mechanical properties similar to carbon steel, which are better than the mechanical properties of grey cast iron. The 1.5 mm/s crosshead speed created a tensile strength of 549.8 N/mm 2 . It gradually declined to 401.4 N/mm 2 at 4.5 mm/s and 302.6N/mm 2 at 9 mm/s. Differentiation in strain rates at the speed variations caused the decline in tensile strength, creating energy lost due to the plastic deformation that resulted in the quick break in the specimen. The increase in strain rates influenced the yield strength results. These occurrences meant that the slower pullout generated a more static material. Thus, there was no declination in the tensile strength. Observed from the fault morphology results, a variant with 1.5 mm/s speed had ductile fractures, 4.5 mm/s speed variant had a combination of ductile-brittle fractures and 9 mm/s speed variant had brittle fractures.

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“…The research on ADI is focused on the modification of matrix microstructure through heat treatment or alloying elements additions . According to different requirements of the application, the microstructure can be modified by controlling the austenite and austempered process .…”

Section: Introductionmentioning

confidence: 99%

Influence of Graphite Nodules on the Microstructure and Mechanical Properties of Hollow Ductile Iron Pipe after Austempering Treatment

Wang

Gao

et al. 2019

steel research int.

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Herein, the microstructure and mechanical properties of ductile iron with different numbers of graphite nodules before and after austempering treatment are systematically investigated. The results show that the amounts of graphite nodules affect the microstructure and resulting mechanical properties of ductile iron. The ferrite fraction in an as-cast matrix decreases with the increase in graphite nodules; this outcome is mainly attributed to the cooling rate. The matrix of ductile iron after austempering treatment is composed of acicular ferrite and retained austenite. The acicular ferrite is refined with the increase in graphite nodules, because the increase in interface between graphite/austenite provides more nucleation sites during austempering treatment. Meanwhile, the formation of ferrite causes carbon atoms to diffuse into the surrounding matrix, giving rise to the increase in carbon concentration of untransformed austenite and further stabilizing the retained austenite. Hence, the volume fraction of retained austenite and the carbon content in it both increase with the increase in graphite nodules. The amounts in graphite nodules affect the mechanical properties significantly after austempering treatment; this outcome is related to the phase constituents of ductile iron after austempering treatment. Herein, the detailed mechanisms are discussed.

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Influence of intercritical austempering on the microstructure and mechanical properties of austempered ductile cast iron (ADI)

Cited by 66 publications

References 18 publications

Microstructural damage evaluation of ferritic-ausferritic spheroidal graphite cast iron

Microstructural damage evaluation of ferritic-ausferritic spheroidal graphite cast iron

Crosshead Speed Effects on Ferro Casting Ductile (Fcd) Tensile Strength and Fault Morphology

Influence of Graphite Nodules on the Microstructure and Mechanical Properties of Hollow Ductile Iron Pipe after Austempering Treatment

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