Notch Effects on Impact and Bending Characteristics of Spheroidal Graphite and Compacted Vermicular Graphite Cast Irons with Various Matrices

Nobuki, Tohru; Hatate, Minoru; Shiota, Toshio

doi:10.4028/www.scientific.net/kem.457.392

Cited by 3 publications

(8 citation statements)

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“…Figure 10 shows the microscopic observation of side view of polished ADI α=1.0 and α= 3.0 impact specimens which observed several loading point during the bending test. From these results, the main macro crack initiates at the maximum load point through micro cracks starting from the graphite edges in the stage prior to the maximum load point [15] [16]. Figure 11 shows the relation between crack length and load-displacement curves of ADI α = 1.0 and α = 3.0 specimens in bending test.…”

Section: Observation Of Crack Initiationmentioning

confidence: 99%

“…Figure 12 shows the relation between the impact characteristics of these various matrix tested at room temperature. In the case of FDI sample [15], However, for PDI [16] and ADI sample, the absorbed energy is almost constituted of crack initiation energy, because crack propagation energy is negligible. In this way, if we want to obtain higher toughness samples, the crack initiation energy need to be improved.…”

Section: Observation Of Crack Initiationmentioning

confidence: 99%

“…In this way, if we want to obtain higher toughness samples, the crack initiation energy need to be improved. Figure 13 shows the SEM observation photos of fracture surfaces of FDI [15], PDI [16] and ADI α = 1.0 specimens in brittle, transition and ductile region of impact transition curves. In the upper shelf region, the fracture surfaces beneath the external notch root is of ductile which consists of the dimples nucleated by …”

Section: Observation Of Crack Initiationmentioning

confidence: 99%

“…Although cast iron has various superior characteristics as mentioned above, the presence of graphite causes some undesirable affection to various mechanical properties due to the decrease of the effective sectional area of matrix and producing internal notch effect [4] [5] [6], therefore, cast iron is regarded as a material with a less anti-impact characteristic than that of steel. On the other hand, cast iron is also regarded as a material which is less sensitive against outer-notch than steel [7], but this characteristic has not been systematically investigated so far [8].…”

Section: Introductionmentioning

confidence: 99%

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Impact Properties of Austempered Spheroidal Graphite Cast Irons

Nobuki¹,

Hatate²,

Shiota³

2017

MSA

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This study aims to clarify the influence of external notch on impact characteristics of high toughness ductile cast irons prepared by austempering heat treatment. We produced ductile cast irons samples with various matrix microstructure tested by Charpy impact within five kinds of external notches whose stress concentration factors (α), with values taken from 1.0 (Unnotched) to 4.8. In addition, to clarify the initiation process of impact characteristics, we observed the evolution of microstructure surface during bending tests with a slow loading speed for the un-notched and the notched impact samples. The results showed that the impact fracture energy decreases strongly in the range of α from 1 to 2.3 but decreases slightly for α larger than 3.Moreover, the impact value of samples with austempered microstructure is sensitive to the external notch shape. The impact transition temperature increases with increasing the stress concentration factor. The fracture energy is decreasing with the external notch from the impact test since the crack initiation energy is directly affected by this later. This work contributes to get a better understanding in the basic theories of external notch effect on impact characteristics of austempered spheroidal graphite cast irons (ADI).

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Section: Observation Of Crack Initiationmentioning

confidence: 99%

Section: Observation Of Crack Initiationmentioning

confidence: 99%

Section: Observation Of Crack Initiationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Impact Properties of Austempered Spheroidal Graphite Cast Irons

Nobuki¹,

Hatate²,

Shiota³

2017

MSA

Self Cite

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“…In addition, there are no methods that can be used to identify the direction of crack propagation in the fracture surface of a particular FDI. In general, the investigations about DI have been focused on the study of the mechanical properties using mechanical tests under different loading configurations . Some articles analyse the effect of the graphite nodule on the fracture process either experimentally or via computational techniques, mainly focusing on the nucleation and growth of voids as a result of the matrix–graphite interphase debonding .…”

Section: Introductionmentioning

confidence: 99%

Study of the fracture of ferritic ductile cast iron under different loading conditions

Fernandino

Boeri

2014

Fatigue Fract Eng Mat Struct

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This work is a continuation of the studies presented in a recent paper by the authors, where the fracture surfaces of pearlitic ductile cast iron under different loading conditions were exhaustively analysed. In this study, fracture surfaces of ferritic ductile cast iron (or ferritic spheroidal graphite cast iron) generated under impact, bending and fatigue loading conditions were characterised and compared. The fracture surfaces were characterised qualitatively and quantitatively from the observation under a scanning electron microscope. The fracture mechanisms in each case were identified. For impact tests, as test temperature increases, the dominant fracture mechanism changes from brittle to ductile. For bending tests, a fully ductile fracture micromechanism dominates the surface. In fatigue tests, the surface shows a mix of flat facets that appear to be cleavage facets and ductile striations, but the typical fatigue striations are not easily found on the fracture surface. Methodologies for the determination of the macroscopic direction of main crack propagation in both ductile and brittle failure modes are proposed. These allow identifying main crack propagation direction with good approximation. The results are potentially useful to identify the nature of loading conditions in a fractured specimen of ferritic spheroidal graphite cast iron. The authors believe that it is necessary to extend the methodologies proposed in samples with different geometry and size, before they can be used to provide additional information to the classical fractographic analysis.

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Rule modeling of ADI cast iron structure for contradictory data

Soroczyński¹,

Biernacki²,

Kochański³

2022

cmms

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Ductile iron is a material that is very sensitive to the conditions of crystallization. Due to this fact, the data on the cast iron properties obtained in tests are significantly different and thus sets containing data from samples are contradictory, i.e. they contain inconsistent observations in which, for the same set of input data, the output values are significantly different.The aim of this work is to try to determine the possibility of building rule models in conditions of significant data uncertainty. The paper attempts to determine the impact of the presence of contradictory data in a data set on the results of process modeling with the use of rule-based methods. The study used the well-known dataset (Materials Algorithms Project Data Library, n.d.) pertaining to retained austenite volume fraction in austempered ductile cast iron. Two methods of rulebased modeling were used to model the volume of the retained austenite: the decision trees algorithm (DT) and the rough sets algorithm (RST).The paper demonstrates that the number of inconsistent observations depends on the adopted data discretization criteria. The influence of contradictory data on the generation of rules in both algorithms is considered, and the problems that can be generated by contradictory data used in rule modeling are indicated.

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Notch Effects on Impact and Bending Characteristics of Spheroidal Graphite and Compacted Vermicular Graphite Cast Irons with Various Matrices

Cited by 3 publications

References 0 publications

Impact Properties of Austempered Spheroidal Graphite Cast Irons

Impact Properties of Austempered Spheroidal Graphite Cast Irons

Study of the fracture of ferritic ductile cast iron under different loading conditions

Rule modeling of ADI cast iron structure for contradictory data

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