Damage effect on the fracture toughness of nodular cast iron. Part 1: Damage characterization and plastic flow stress modeling

Journal Article · Sat Nov 01 04:00:00 EST 1997 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-997-0182-7· OSTI ID:556460

Dong, M J; Prioul, C; Francois, D ^[1]

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1. Ecole Centrale de Paris, Chatenay Malabry (France)

After chemical, morphological, and mechanical characterization of ductile cast iron, the damage mechanisms were studied by tensile tests inside the scanning electron microscope (SEM). The evolutions of Young`s modulus and of Poisson`s ratio were measured in uniaxial tensile tests. Compression tests were used to measure the pressure sensitivity coefficient of the flow stress. The damage is produced by early initiation of cavities at the pole cap of graphite nodules by debonding of the interface, followed by the growth of cavities. The mechanical behavior was modeled in the elastic region by calculating the Hashin-Shtrickman bounds. This provided the elastic constants for the graphite nodules. The plastic behavior was modeled by considering that the graphite nodules were replaced by voids. The critical interfacial stress for debonding was determined by analytical as well as by finite-element calculations. The growth rate of cavities was deduced from the evolution of the Poisson`s ratio and was compared with predictions from Gurson`s potential. The stress-strain behavior could be modeled either by extension of the Mori-Tanaka analysis in the plastic range or by finite-element computations. This allowed a fair prediction of the observed behavior.

• Sponsoring Organization: USDOE
• OSTI ID: 556460
• Journal Information: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 11 Vol. 28; ISSN MMTAEB; ISSN 1073-5623
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CAST IRON
CAVITIES
FINITE ELEMENT METHOD
FLOW STRESS
FRACTURE PROPERTIES
INTERFACES
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MICROSTRUCTURE
POISSON RATIO
PREDICTION EQUATIONS
YOUNG MODULUS