IntegrityAssessment

Tensile Flow Behavior and Strain Hardening of Metallic Materials

Strain hardening is the ability of metallic materials to harden when straining, and it is investigated through mathematical derivative approach. Strain hardening occurs alongside any industrial forming thermo-mechanical process at high and room temperatures, and/or during service from high to cryogenic temperatures. Though the general scenario of strain hardening of pure metals is widely known to be based on dynamics of dislocations, first introduced in the previous century by Vito Volterra, and on the co-existing competing micro-mechanisms of hardening dislocation multiplication and softening through dynamic recovery, the detailed resulting industrial metallic alloys have to be experimentally through tensile tests and theoretically investigated, since additional micro-phenomena can be present during deformation like, for instance, Transformation Induced Plasticity (TRIP) in Austempered Ductile Irons (ADIs) and Twinning Induced Plasticity (TWIP) in high Mn steels. Physical based models of strain hardening are studied, giving solid correlations between tensile strain hardening behavior of the alloys and the microstructure features observed through HR-SEM with EBSD and XRD.

Relevant publications:

On Ausferrite Produced in Thin Sections: Stability Assessment through Round and Flat Tensile Specimen Testing
G. Angella, R. Donnini, D. Ripamonti, F. Bonollo, B. Cygan, M. Gorny,
Metals, Open Access Volume 13, Issue 1, January 2023 Article number 105. DOI: doi.org/10.3390/met13010105

The Role of Microstructure on the Tensile Plastic Behaviour of Ductile Iron GJS 400 Produced through Different Cooling Rates – Part II: Tensile Modelling
G. Angella, R. Donnini, D. Ripamonti, M. Górny, F. Zanardi, Metals 9(9) (2019), 1019. DOI: doi.org/10.3390/met9091019

An Insight into the Defects-Driven Plasticity in Ductile Cast Irons
G. Angella, T. Taloni, M. Gorny, J. Tarasiuk, S. Wronski, R. Montanari, M. Pedranz, M. Benedetti, V. Fontanari, D. Lusuardi, Materials, Open Access, Volume 16, Issue 10, May 2023 Article number 3748. DOI: doi.org/10.3390/ma16103748

Mechanical and Microstructural Characterization of AF955 (UNS N09955) Nickel-Based Superalloy After Different Heat Treatments
A. Serafini, G. Angella, C. Malara, M.F. Brunella, METALLURGICAL AND MATERIALS TRANSACTIONS A (2018) VOLUME 49A, NOVEMBER 2018—5339. DOI: https://doi.org/10.1007/s11661-018-4876-9.

Working group:

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Defectiveness Assessment of Industrial Metallic Alloys

An integral part of the alloys microstructure are defects and metallurgical discontinuities which in foundry products can take on particularly high densities compared to wrought components, causing high variability in their mechanical properties. The integrity of foundry products for industrial components should be easily assessable through procedures and quality indices that summarize the PMP reports. Experimental-based quality indices on tensile strength (or yield strength) and elongation at rupture have been widely developed in the past, while innovative procedures and constitutive models have been developed and improved in ICMATE Milan for classification and evaluation of microstructural integrity especially for ductile cast irons and foundry aluminum alloys by physical-base constitutive equations describing the tensile strain hardening behavior. The physical bases of the PMP relationships however require continuous validation which naturally refers to the microstructural characterization though using advanced microstructural techniques, like HR-SEM with EBSD and XRD.

Relevant publications:

On Ausferrite Produced in Thin Sections: Stability Assessment through Round and Flat Tensile Specimen Testing
G. Angella, R. Donnini, D. Ripamonti, F. Bonollo, B. Cygan, M. Gorny,
Metals, Open Access Volume 13, Issue 1, January 2023 Article number 105. DOI: doi.org/10.3390/met13010105

The Role of Microstructure on the Tensile Plastic Behaviour of Ductile Iron GJS 400 Produced through Different Cooling Rates – Part II: Tensile Modelling
G. Angella, R. Donnini, D. Ripamonti, M. Górny, F. Zanardi, Metals 9(9) (2019), 1019. DOI: doi.org/10.3390/met9091019

An Insight into the Defects-Driven Plasticity in Ductile Cast Irons
G. Angella, T. Taloni, M. Gorny, J. Tarasiuk, S. Wronski, R. Montanari, M. Pedranz, M. Benedetti, V. Fontanari, D. Lusuardi, Materials, Open Access, Volume 16, Issue 10, May 2023 Article number 3748. DOI: doi.org/10.3390/ma16103748

Mechanical and Microstructural Characterization of AF955 (UNS N09955) Nickel-Based Superalloy After Different Heat Treatments
A. Serafini, G. Angella, C. Malara, M.F. Brunella, METALLURGICAL AND MATERIALS TRANSACTIONS A (2018) VOLUME 49A, NOVEMBER 2018—5339. DOI: https://doi.org/10.1007/s11661-018-4876-9.

Working group:

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Microstructure Stability of Metallic Alloys in Severe Working Conditions

Metallic materials for high temperature applications, like Ni base superalloys, are characterized by high microstructure stability and the feasibility of being strengthened in different ways, such as solid solution and precipitation of second strengthening phases g’ and/or g’’, ordered and crystallographically coherent with the austenitic matrix FCC-g. Their industrial production route is very complex, being based on advanced foundry techniques like vacuum induction melting (VIM), vacuum arc remelting (VAR) and electroslag remelting (ESR), and on final expensive heat treatments to confer the desired microstructure. Tensile and strain hardening behavior analysis at room and high temperature of the alloys of final products gives useful insight of the optimal industrial production routes. Also, other microstructural features are relevant for the mechanical behavior of metallic alloys at high temperatures, like the grain boundaries that at medium and high temperatures can be weak features, causing a ductility loss in metallic alloys like Ni base superalloys, steels, aluminum alloys and cast irons. The innovative approach for defectiveness assessment is applied to grained metallic alloys tensile-tested at high temperatures for assessing microstructure stability and ductility loss, supported by advanced microstructural techniques, like HR-SEM with EBSD and XRD.

Relevant publications:

On Ausferrite Produced in Thin Sections: Stability Assessment through Round and Flat Tensile Specimen Testing
G. Angella, R. Donnini, D. Ripamonti, F. Bonollo, B. Cygan, M. Gorny,
Metals, Open Access Volume 13, Issue 1, January 2023 Article number 105. DOI: doi.org/10.3390/met13010105

The Role of Microstructure on the Tensile Plastic Behaviour of Ductile Iron GJS 400 Produced through Different Cooling Rates – Part II: Tensile Modelling
G. Angella, R. Donnini, D. Ripamonti, M. Górny, F. Zanardi, Metals 9(9) (2019), 1019. DOI: doi.org/10.3390/met9091019

An Insight into the Defects-Driven Plasticity in Ductile Cast Irons
G. Angella, T. Taloni, M. Gorny, J. Tarasiuk, S. Wronski, R. Montanari, M. Pedranz, M. Benedetti, V. Fontanari, D. Lusuardi, Materials, Open Access, Volume 16, Issue 10, May 2023 Article number 3748. DOI: doi.org/10.3390/ma16103748

Mechanical and Microstructural Characterization of AF955 (UNS N09955) Nickel-Based Superalloy After Different Heat Treatments
A. Serafini, G. Angella, C. Malara, M.F. Brunella, METALLURGICAL AND MATERIALS TRANSACTIONS A (2018) VOLUME 49A, NOVEMBER 2018—5339. DOI: https://doi.org/10.1007/s11661-018-4876-9.

Working group:

Integrity assessment

of industrial products

ACTIVITIES:

Tensile Flow Behavior and Strain Hardening of Metallic Materials

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Defectiveness Assessment of Industrial Metallic Alloys

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Microstructure Stability of Metallic Alloys in Severe Working Conditions

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Link Istituzionali

CNR – ICMATE

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