Microstructure, Mechanical Properties, Toughness, Wear Characteristics and Fracture Phenomena of Austenitised and Austempered Low-Alloyed Ductile Iron

Fatahalla, N.; Hussein, O.

doi:10.4236/oalib.1101012

Cited by 10 publications

(9 citation statements)

References 21 publications

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“…To determine the performance of any ductile iron, the quality index (QI) including the tensile strength and the elongation was introduced [25], but as ADI is used for railways and other moving components, the QI was modified by a wear resistance unit [7]. The authors [7] proved that the QI changes with an increase of the austempering temperature: the higher the QI, the better the strength and wear properties of the ADI.…”

Section: Introductionmentioning

confidence: 99%

Influence of Austempering Temperatures on the Microstructure and Mechanical Properties of Austempered Ductile Cast Iron

Bendikienė

Čiuplys

Česnavičius

et al. 2021

Metals

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The influence of the austempering temperatures on the microstructure and mechanical properties of austempered ductile cast iron (ADI) was investigated. ADI is nodular graphite cast iron, which owing to higher strength and elongation, exceeds mechanical properties of conventional spheroidal graphite cast iron. Such a combination of properties is achieved by the heat treatment through austenitization, followed by austempering at different temperatures. The austenitization conditions were the same for all the samples: temperature 890 °C, duration 30 min, and quenching in a salt bath. The main focus of this research was on the influence of the austempering temperatures (270 °C, 300 °C, and 330 °C) on the microstructure evolution, elongation, toughness, and fatigue resistance of ADI modified by certain amounts of Ni, Cu, and Mo. The Vickers and Rockwell hardness decreased from 535.7 to 405.3 HV/1 (55.7 to 44.5 HRC) as the austempering temperature increased. Optical images showed the formation of graphite nodules and a matrix composed of ausferrite; the presence of these phases was confirmed by an XRD diffraction pattern. A fracture surface analysis revealed several types of the mechanisms: cleavage ductile, transgranular, and ductile dimple fracture. The stress-controlled mechanical fatigue experiments revealed that a 330 °C austempering temperature ensures the highest fatigue life of ADI.

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Section: Introductionmentioning

confidence: 99%

Influence of Austempering Temperatures on the Microstructure and Mechanical Properties of Austempered Ductile Cast Iron

Bendikienė

Čiuplys

Česnavičius

et al. 2021

Metals

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“…To determine the performance of any ductile iron, a parameter called the quality index (QI), which is a dimensionless number, was introduced, using both tensile strength and elongation [34]. Since ADI is used in wear resistant applications, such as railways and impeller earth moving components, the quality index equation was modified by the current authors to include wear resistance, and is given below:…”

Section: Quality Indexmentioning

confidence: 99%

Austempered Ductile Iron (ADI): Influence of Austempering Temperature on Microstructure, Mechanical and Wear Properties and Energy Consumption

Sellamuthu

Samuel

Dinakaran

et al. 2018

Metals

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Alloyed Ductile iron, austenitized at 840 • C for 30 min in a special sealed austempering furnace, was austempered for 30 min in molten salt mixture at 4 trial temperatures of 300 • C, 320 • C, 340 • C and 360 • C. Tensile strength, yield strength, percentage elongation and impact energy were evaluated for the as-cast and austempered samples. Microstructures were investigated using microscopy, coupled with analyzing software and a scanning electron microscopy. The specific wear of samples was tested using pin-on-disc wear testing machine. X-ray diffraction was performed to calculate the amount of retained austenite present in the ausferrite matrix. As-cast microstructure consists of ferrite and pearlite, whereas austempered ductile iron (ADI) contains a mixture of acicular ferrite and carbon enriched austenite, called "ausferrite". Hardness and strength decreased, whereas ductility and impact strength improved with an increase in the austempering temperature. XRD analysis revealed that the increase in austempering temperature increased the retained austenite content. A decrease in wear resistance with austempering temperature was observed. Modified Quality Index (MQI) values were envisaged, incorporating tensile strength, elongation and wear resistance. MQI for samples austempered at 340 • C and 360 • C showed a better combination of properties. About an 8% reduction in energy consumption was gained when the heat treatment parameters were optimized.

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“…Usually, an optimization of properties of this material for specific applications was carried out by a selection of its chemical composition and by controlling the casting technology [1][2][3]. In the published works some attempts have been also presented to modify the matrix microstructure by tailoring heat treatment parameters, e.g., in the case of austempered ductile irons (ADIs) [1][2][3][4][5][6] or spheroidal cast irons (SCIs) in welded joints [7].…”

Section: Introductionmentioning

confidence: 99%

Micromechanism of Damage of the Graphite Spheroid in the Nodular Cast Iron During Static Tensile Test

Warmuzek

Polkowska

2020

JMMP

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This work was focused on two particular phenomena contributing to a damage process of nodular cast iron under tensile stress: Internal destruction of graphite nodule and debonding at graphite/matrix (G-M) interface. The G-M debonding was analyzed depending on the phase characteristics of the metal matrix and with the increase in the distance of the observation field from the main crack surface. Typical morphological effects of decohesion in the graphite-matrix microregions related to an internal structure of graphite nodule were revealed and classified. The obtained results of the microscopic observations suggest that the path of both types of internal cracks in the graphite nodule passed through areas of weakened cohesion. Detailed microscopic observations allowed revealing some additional phenomena associated with G-M debonding along the G/M interface. In the most ductile of the tested alloys, with ferritic and ausferritic matrix, the G-M debonding was preceded by the formation of a layer of shifted graphene plates in the external envelope of the spheroid. In the alloys of polyphase pearlitic and ausferritic matrix, the revealed morphology of the G-M interface suggests that G-M debonding might be delayed by the interaction with some phase components as cementite lamellae and austenite plates.

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Microstructure, Mechanical Properties, Toughness, Wear Characteristics and Fracture Phenomena of Austenitised and Austempered Low-Alloyed Ductile Iron

Cited by 10 publications

References 21 publications

Influence of Austempering Temperatures on the Microstructure and Mechanical Properties of Austempered Ductile Cast Iron

Influence of Austempering Temperatures on the Microstructure and Mechanical Properties of Austempered Ductile Cast Iron

Austempered Ductile Iron (ADI): Influence of Austempering Temperature on Microstructure, Mechanical and Wear Properties and Energy Consumption

Micromechanism of Damage of the Graphite Spheroid in the Nodular Cast Iron During Static Tensile Test

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