The development of ADI and IDI in Italy

Masaggia, Stefano

doi:10.1016/j.proeng.2010.03.158

Cited by 11 publications

(8 citation statements)

References 2 publications

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“…The microstructure consists of acicular ferrite, retained austenite, graphite nodules and carbides. Ni, Cu and Mo are known as the main alloying elements for influencing the ADI heat treatment and phase transition kinetics [ 7 ]. The amount and stability of the retained austenite, depending on the austenitization and austempering temperatures, change the characteristic of the TRIP effect appearing under plastic deformation or low temperature [ 8 , 9 ].…”

Section: Introductionmentioning

confidence: 99%

Phase Transition Kinetics in Austempered Ductile Iron (ADI) with Regard to Mo Content

et al. 2020

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The phase transformation to ausferrite during austempered ductile iron (ADI) heat treatment can be significantly influenced by the alloying element Mo. Utilizing neutron diffraction, the phase transformation from austenite to ausferrite was monitored in-situ during the heat treatment. In addition to the phase volume fractions, the carbon enrichment of retained austenite was investigated. The results from neutron diffraction were compared to the macroscopic length change from dilatometer measurements. They show that the dilatometer data are only of limited use for the investigation of ausferrite formation. However, they allow deriving the time of maximum carbon accumulation in the retained austenite. In addition, the transformation of austenite during ausferritization was investigated using metallographic methods. Finally, the distribution of the alloying elements in the vicinity of the austenite/ferrite interface zone was shown by atom probe tomography (APT) measurements. C and Mn were enriched within the interface, while Si concentration was reduced. The Mo concentration in ferrite, interface and austentite stayed at the same level. The delay of austenite decay during Stage II reaction caused by Mo was studied in detail at 400 °C for the initial material as well as for 0.25 mass % and 0.50 mass % Mo additions.

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Section: Introductionmentioning

confidence: 99%

Phase Transition Kinetics in Austempered Ductile Iron (ADI) with Regard to Mo Content

et al. 2020

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“…Austempered ductile iron (ADI), the result of an austempering treatment, represents the top grade of the NCI family range [2,3]. However, the cost increase of alloying elements used in the low-strength ADI grades has led to a slow growth rate of new ADI applications in recent years and created the opportunity for the invention of Perferritic Isothermal Ductile Iron (IDI) [4].…”

Section: Introduction *mentioning

confidence: 99%

Microstructure vs. Near-threshold Fatigue Crack Growth Behavior of an Heat-treated Ductile Iron

Konečná

Bubenko

Nicoletto

2012

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Perferritic isothermal ductile iron (IDI®) is an intermediate grade between the low-strength grades of austempered ductile iron (ADI) and pearlitic ductile iron (DI) recently developed by Zanardi Fonderie Italy. IDI is produced by heat-treating an unalloyed nodular cast iron. The specific matrix microstructure is called “Perferritic” and consists predominantly of ferrite and pearlite. Compared to the pearlitic grades of nodular ductile iron, IDI combines similar strength with higher toughness as a result of the isothermal heat treatment.

In this contribution the fatigue crack growth resistance and K_ath of IDI are investigated and correlated to mechanical properties and microstructural features. The threshold K_a was determined using the load shedding technique as per ASTM Standard E-647 using CT specimens extracted from a cast block. Tensile specimens were extracted from the broken CT halves and used to determine the static mechanical properties. A metallographic investigation was carried out to correlate structural features and mechanical properties.

DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1336

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“…This unique microstructure is the reason why it is possible to achieve the strength of fully pearlitic grades, even in the presence of a significant ferrite fraction. 5 Under uniaxial tensile test conditions, both NCFPDIs and IDIs exhibit considerable ductility, which is mainly due to the presence of large ferrite fraction, that supports the use of von Mises yield criterion. 6 Recently, new classes of high-performing ductile iron have become commercially available.…”

Section: Introductionmentioning

confidence: 54%

“…5 Defects on un-machined surfaces are not sharp enough to behave like cracks. For this, the Wöhler SN curve slope is sufficient enough to enable the use of Locati method.…”

Section: Plastic Flow Shape/fracture and Notch Mechanicsmentioning

confidence: 99%

A Contribution to New Material Standards for Ductile Irons and Austempered Ductile Irons

et al. 2016

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Some results of materials characterization activities, dedicated to classical and notch mechanics fatigue and elastoplastic properties, have already been published for some Ferritic-Pearlitic Ductile Iron, including the patented heat treated Isothermed (IDI) and Austempered Ductile Iron (ADI) grades. Others have not yet been published. The possible use of all of these results in new standards is discussed in this paper. It is proposed that new standards should provide a criterion that is able to measure the process quality that represents more accurately the actual market needs and manufacturing capabilities. Classification of grades, considered by existing standards, is based on minimum properties for strength and ductility parameters that are separately evaluated. A different approach that is based on a quality index, which considers strength and ductility all in one, is proposed. However, this new proposed approach may not be sufficient to provide a satisfactory classification for the ADIs. This is because their fracture mechanical behavior and machinability can be correlated with their austenite stability. It could also be insufficient for the classification of the recent High Silicon Solid Solution Strengthened Ductile Irons that exhibit a decreasing ultimate tensile strength/proof stress ratio with increasing Si. For construction steels, fracture mechanics properties are sometimes believed to be related to the Charpy impact energy. This paper introduces an innovative practical and inexpensive data analysis, performed on the tensile test curve, which appears to be a potential estimator of fracture mechanical properties, at least for ADIs, where said properties could be correlated with the austenite stability.

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The development of ADI and IDI in Italy

Cited by 11 publications

References 2 publications

Phase Transition Kinetics in Austempered Ductile Iron (ADI) with Regard to Mo Content

Phase Transition Kinetics in Austempered Ductile Iron (ADI) with Regard to Mo Content

Microstructure vs. Near-threshold Fatigue Crack Growth Behavior of an Heat-treated Ductile Iron

A Contribution to New Material Standards for Ductile Irons and Austempered Ductile Irons

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