The sigmoidal strain hardening behaviour of a metastable AISI 301LN austenitic stainless steel as a function of temperature

Mukarati, Tulani W.; Mostert, R.J.; Siyasiya, Charles Witness

doi:10.1016/j.msea.2020.139741

Cited by 12 publications

(23 citation statements)

References 21 publications

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“…The exact behavior depends on several factors, including the temperature (because the thermodynamic driving force for martensite formation is greater at lower temperature) and the stacking fault energy, with a low value facilitating the cross-slip that can be involved in the phase transformation. [48][49][50][51] The composition is important, including the carbon and nitrogen levels. High levels of these tend to retard martensite formation, although very low levels of carbon lead to a reduction in the hardness of the martensite.…”

Section: Basic Operationmentioning

confidence: 99%

Profilometry‐Based Inverse Finite Element Method Indentation Plastometry

Clyne

Campbell²,

Burley³

et al. 2021

Adv Eng Mater

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This is a review of the current state‐of‐the‐art regarding a particular approach to extraction of the (quasistatic) stress–strain relationship of a metallic sample from an indentation experiment. It is based on the application of a relatively high load (kN range) to the sample via a large spherical indenter (≈1 mm radius), followed by measurement of the indent profile. This profile is then used as the target outcome for inverse finite element method (FEM) modeling of the test, aimed at converging on the best fit set of parameter values in a constitutive plasticity law (true stress–true strain relationship). This can then be used to simulate any specified loading configuration, including a conventional tensile test. Commercial products are now available in which the indentation, profilometry, and convergence operations are all automated and completed within a few minutes. The review covers the various conceptual and practical issues involved in implementation and optimization of these procedures, including both those related to the measurement system (experimental and FEM simulation) and those associated with the sample (such as anisotropy, inhomogeneities, and residual stresses). An attempt is made to convey an impression of the expected levels of reliability and also the scope for obtaining insights that are not readily obtainable using other types of test.

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Section: Basic Operationmentioning

confidence: 99%

Profilometry‐Based Inverse Finite Element Method Indentation Plastometry

Clyne

Campbell²,

Burley³

et al. 2021

Adv Eng Mater

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“…However, the alloy does not demonstrate high mechanical austenite stability, as it readily strain hardens through SIMT at ambient temperatures. [ 4 ]…”

Section: Introductionmentioning

confidence: 99%

Modeling of the Kinetics of Strain‐Induced Martensite Transformation and the Transformation‐Induced Plasticity Effect in a Lean‐Alloyed Metastable Austenitic Stainless Steel

Mukarati

Mostert

Siyasiya

2021

steel research int.

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This article investigates the influence of temperature and strain on second‐phase transformation strengthening and the resulting mechanical properties in a lean AISI 301LN austenitic stainless steel within a temperature range of −60 to 180 °C. The volume fraction of martensite evolved is determined using nondestructive magnetic Ferritescope measurements that are adjusted by using a calibration factor of 1.7, which is established using the saturation magnetization measurements, X‐ray, and neutron diffraction measurements. The kinetics of strain‐induced martensite transformation (SIMT) as a function of strain and temperature is accurately described by a set of modified constitutive Boltzmann sigmoidal equations at temperatures below 75 °C. For this steel, the Md (30/50) temperature is determined as 61 °C. The absolute Md temperature is established as ≈109 °C, and no athermal transformation to martensite is observed upon cooling to −270 °C using cryogenic neutron diffraction facilities. Extended JMAK analysis of the transformation is used to shed light on the mechanism of martensitic transformation. It is found that the transformation‐induced plasticity (TRIP) effect due to SIMT is at a maximum at 75 °C, which is the maximum elongation temperature (MET) and calculations are performed regarding alloy development which will reduce the MET to room temperature.

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“…A number of papers [ 5–8 ] have been published that present both theoretical background relating to the mechanical behavior of MASS and experimental stress–strain curves (converted in some cases to true stress–true strain relationships, using the analytical relationships that apply up to the onset of necking). It is clear that mechanical stimulation of the formation of martensite, with an associated increase in the “hardness” (work hardening rate) can have a marked effect on the nature of the curve.…”

Section: Introductionmentioning

confidence: 99%

“…In any event, a representative set [ 7 ] of tensile stress–strain curves is shown in Figure , relating to a particular MASS steel tested over a range of temperatures. The changes in work hardening rate, particularly the increase after a plastic strain of the order of 5–10%, are quite dramatic.…”

Section: Introductionmentioning

confidence: 99%

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A Constitutive Stress–Strain Law for Metals with Sigmoidal Curves

Clyne

Gu²

2021

Adv Eng Mater

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A formulation is proposed for true stress–true strain relationships in the plastic regime that exhibit sigmoidal shapes, such as those of certain metastable austenitic stainless steels (MASS). It contains two terms, broadly accounting for contributions to hardening from conventional plasticity and from mechanical stimulation of martensite formation. It is a continuous function, designed to cover the plastic strain range from zero up to several tens of percent. It is shown that it is suitable for capture of a range of curve shapes of this type—experimental data from tensile testing of a MASS alloy over a range of temperature, with good fidelity. The formulation incorporates six independent parameters, although there may be scope for limiting the range of values that they can have, facilitating convergence operations. Information is presented about how convergence is obtained. The equation is thus expected to be suitable for use in finite element method (FEM) models for simulation of plastic deformation in various scenarios, including indentation. Future work will involve exploration of the details of this.

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The sigmoidal strain hardening behaviour of a metastable AISI 301LN austenitic stainless steel as a function of temperature

Cited by 12 publications

References 21 publications

Profilometry‐Based Inverse Finite Element Method Indentation Plastometry

Profilometry‐Based Inverse Finite Element Method Indentation Plastometry

Modeling of the Kinetics of Strain‐Induced Martensite Transformation and the Transformation‐Induced Plasticity Effect in a Lean‐Alloyed Metastable Austenitic Stainless Steel

A Constitutive Stress–Strain Law for Metals with Sigmoidal Curves

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