Transition temperature and fracture mode of as‐castand austempered ductile iron

Rajnović, Dragan; Erić, Olivera; Šidjanin, Leposava

doi:10.1111/j.1365-2818.2008.02125.x

Cited by 12 publications

(11 citation statements)

References 16 publications

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“…a). It is also important to note that for these grades of ADI, the lower and upper shelf temperatures are approximately located at −120 °C and 60 °C respectively . Consequently, a temperature of −20 °C is located within the ductile to brittle transition temperature range.…”

Section: Resultsmentioning

confidence: 95%

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Fractographic analysis of austempered ductile iron

Fernandino

Boeri

2015

Fatigue Fract Eng Mat Struct

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A B S T R A C T This investigation involves a systematic study of the fracture surfaces of two grades of austempered ductile iron (ADI) broken under quasi-static, dynamic and cyclic loading conditions. The study used electron microscopy, optical microscopy and image postprocessing. The results show that the predominating fracture mechanism in ADI upon impact loading changes from quasi-cleavage to ductile (with little areas of cleavage facets) as the testing temperature increases. Noticeably, even at the lower temperatures tested, the fracture surface of ADI shows clear signs of ductile fracture mechanisms. In particular, graphite nodule cavities suffer marked plastic deformation. Fracture after bending tests at room temperature was characterized by a mix of quasi-cleavage facets, deformation of the contour of nodular cavities and microvoid coalescence. In the case of fatigue fracture at room temperature, the fracture surfaces show a flat appearance which has notorious differences with those reported for other loading conditions, but the typical fatigue striations were not found. The particular features identified on the fatigue fracture surfaces can be used to identify fatigue failures. It was also shown that the determination of the direction of main crack propagation by using the experimental methodology proposed earlier by the authors is applicable to ADI fractured by impact and quasi-static loads.The results provide information potentially useful to fractographic analyses of ADI, particularly in samples that fail in service under unknown conditions.Keywords austempered ductile iron; bending; fatigue; fractography; fracture surface; impact.N O M E N C L A T U R E L' = Projected length of the fracture profile Lt = Fracture profile length Rs = Superficial roughness Ry = Peak to valley ratio from the fracture profile Y = Length of the nodular contour in parallel axis to the main crack propagation direction X = Length of the nodular contour in perpendicular axis to the main crack propagation direction Β = Angle between the major axis of the equivalent ellipse and the main crack propagation direction I N T R O D U C T I O NThe austempered ductile iron (ADI) is a member of the ductile iron (DI) family which is produced by means of an austempering heat treatment. The different grades are produced primarily by varying the austempering temperature and duration of the heat treatment cycle. 1 Nearly twice as strong as pearlitic DI, ADI still retains high elongation and toughness. This combination provides a material with superior tensile strength, wear resistance and fatigue strength. Its usual applications include gears, crankshafts, connecting rods, agricultural and construction ground engaging parts such as plow points, digger teeth and track shoes, shafts; cams; mining and grinding equipment such as balls and hammers; mill liners and rollers; spring hanger brackets and railroad wear applications. Because of its outstanding mechanical properties, ADI represents an excellent choice of replacement for

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Section: Resultsmentioning

confidence: 95%

“…Most of the fractographic studies focused on ADI are secondary parts of analyses of mechanical properties . Few papers focus on the fractography of DI . In this context, this lack of knowledge may become a limiting factor for the failure analysis of ADI.…”

Section: Introductionmentioning

confidence: 99%

Fractographic analysis of austempered ductile iron

Fernandino

Boeri

2015

Fatigue Fract Eng Mat Struct

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“…A typical brittle fracture of ADI, as a result of the carbide formation during second stage of transformation, as well as a result of low temperature embrittlement, is characterized by wider cleavage facets and clear river patterns [2,3,7,21,22]. The water embrittled ADI material fracture surface contains much finer morphology in the form of narrower serrated facets, forming shallow steps and tear ridges.…”

Section: Discussionmentioning

confidence: 98%

Tensile properties of ADI material in water and gaseous environments

Rajnović

Baloš

Šidjanin

et al. 2015

Materials Characterization

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“…Nevertheless, when the fractured material is PDI, there is a noticeable lack of knowledge. In general, the research about PDI has been focused on the study of the mechanical properties using mechanical tests and qualitative microscopy techniques, but the fracture surface analysis was secondary . Few authors have carried out quantitative studies of the fracture surface topography of samples of DI with different matrix microstructures …”

Section: Introductionmentioning

confidence: 99%

Fracture of pearlitic ductile cast iron under different loading conditions

Fernandino

Boeri

2014

Fatigue Fract Eng Mat Struct

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In this study, fracture surfaces of pearlitic ductile iron generated under impact, bending and fatigue tests were characterised and compared. The fracture mechanisms in each case were identified from the observation of scanning electron microscopy images, and the characteristic topographic features were quantitatively and qualitatively evaluated. Cleavage was the predominant fracture mechanism for impact loading at all test temperatures and for slow bending testing. On the other hand, under fatigue loading, the fracture surfaces showed a mix of cleavage and ductile striation areas. A complex but reliable methodology for the determination of the direction of propagation of the main crack was also proposed, based on a careful analysis of the river patterns along the cleavage planes.

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Transition temperature and fracture mode of as‐castand austempered ductile iron

Cited by 12 publications

References 16 publications

Fractographic analysis of austempered ductile iron

Fractographic analysis of austempered ductile iron

Tensile properties of ADI material in water and gaseous environments

Fracture of pearlitic ductile cast iron under different loading conditions

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