Nano/ultrafine grained austenitic stainless steel through the formation and reversion of deformation-induced martensite: Mechanisms, microstructures, mechanical properties, and TRIP effect

Journal Article · Fri May 15 00:00:00 EDT 2015 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2015.03.031· OSTI ID:22476092

Shirdel, M., E-mail: [e-mail] ^[1]; Mirzadeh, H., E-mail: [e-mail] ^[1]; Advanced Metalforming and Thermomechanical Processing Laboratory, School of Metallurgy and Materials Engineering, University of Tehran, Tehran ^[2]; Parsa, M.H., E-mail: [e-mail] ^[1]; Center of Excellence for High Performance Materials, School of Metallurgy and Materials Engineering, University of Tehran, Tehran ^[2]; Advanced Metalforming and Thermomechanical Processing Laboratory, School of Metallurgy and Materials Engineering, University of Tehran, Tehran ^[2]

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1. School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of)
2. (Iran, Islamic Republic of)

A comprehensive study was carried out on the strain-induced martensitic transformation, its reversion to austenite, the resultant grain refinement, and the enhancement of strength and strain-hardening ability through the transformation-induced plasticity (TRIP) effect in a commercial austenitic 304L stainless steel with emphasis on the mechanisms and the microstructural evolution. A straightforward magnetic measurement device, which is based on the measurement of the saturation magnetization, for evaluating the amount of strain-induced martensite after cold rolling and reversion annealing in metastable austenitic stainless steels was used, which its results were in good consistency with those of the X-ray diffraction (XRD) method. A new parameter called the effective reduction in thickness was introduced, which corresponds to the reasonable upper bound on the obtainable martensite fraction based on the saturation in the martensitic transformation. By means of thermodynamics calculations, the reversion mechanisms were estimated and subsequently validated by experimental results. The signs of thermal martensitic transformation at cooling stage after reversion at 850 °C were found, which was attributed to the rise in the martensite start temperature due to the carbide precipitation. After the reversion treatment, the average grain sizes were around 500 nm and the nanometric grains of the size of ~ 65 nm were also detected. The intense grain refinement led to the enhanced mechanical properties and observation of the change in the work-hardening capacity and TRIP effect behavior. A practical map as a guidance for grain refining and characterizing the stability against grain growth was proposed, which shows the limitation of the reversion mechanism for refinement of grain size. - Graphical abstract: Display Omitted - Highlights: • Nano/ultrafine grained austenitic stainless steel through martensite treatment • A parameter descriptive of a reasonable upper bound on the obtainable martensite • Characterization of martensite by virtue of a new developed magnetic device • Investigation of mechanical properties and TRIP effect and the effect of grain size.

• OSTI ID: 22476092
• Journal Information: Materials Characterization, Vol. 103; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
AUSTENITE
CARBIDES
DEFORMATION
GRAIN GROWTH
GRAIN REFINEMENT
GRAIN SIZE
MAGNETIZATION
MARTENSITE
NANOSTRUCTURES
PHASE TRANSFORMATIONS
PLASTICITY
PRECIPITATION
REDUCTION
ROLLING
SATURATION
STAINLESS STEEL-304L
STRAIN HARDENING
X-RAY DIFFRACTION