Increasing the strength of nanocrystalline steels by annealing: Is segregation necessary?

Renk, Oliver; Hohenwarter, Anton; Eder, Katja; Kormout, Karoline; Cairney, Julie M.; Pippan, Reinhard

doi:10.1016/j.scriptamat.2014.09.023

Cited by 102 publications

(52 citation statements)

References 35 publications

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“…As a result, homogeneous nucleation and, for longer times, normal grain growth were perceived. This kind of behavior has been previously observed in austenitic stainless steels deformed by HPT and subsequently annealed [43].…”

Section: Discussionsupporting

confidence: 79%

Recrystallization and grain growth of a nano/ultrafine structured austenitic stainless steel during annealing under high hydrostatic pressure

et al. 2018

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The aim of this study was to investigate the effect of high hydrostatic pressure applied during annealing on the processes of recrystallization and grain growth in nanostructured austenitic stainless steel 316LVM. The nanostructures were obtained by profile rolling to a total strain of 3.4 and by high-pressure torsion to a total strain of 79. These processes resulted in microstructures consisting of nanotwins and nanograins, respectively. The deformed samples were annealed at 900°C for 10 min under atmospheric or hydrostatic pressures of 2 and 6 GPa. The resulting microstructures were examined using transmission and scanning electron microscopy techniques. The mechanical properties were evaluated in microhardness measurements. It was established that annealing under high hydrostatic pressure retards recrystallization and grain growth, both in profilerolled and high-pressure torsion-processed samples. The magnitude of retardation depends on the character of the grain boundaries. The non-equilibrium high-angle grain boundaries present in the high-pressure torsion-processed sample show higher mobility under pressure than the nanotwinned and lowangle boundaries in the profile-rolled sample.

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Section: Discussionsupporting

confidence: 79%

Recrystallization and grain growth of a nano/ultrafine structured austenitic stainless steel during annealing under high hydrostatic pressure

et al. 2018

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“…It was shown [23] that for bulk nanostructured alloys with a grain size of 100-130 nm, the magnitude of σ y is considerably higher than the value calculated from the Hall-Petch relationship. This phenomenon of superstrength of nanostructured alloys was recently demonstrated in various SPD-processed materials, including Al alloys, [24,31] Ti alloys, [8] carbon steels and stainless steels, [32][33][34] and in an Al-Mg nanocomposite. [35] However, increasing strength of metals and alloys through grain refinement by SPD usually leads to an undesirable drop in their ductility.…”

Section: Superior Strength and Ductilitymentioning

confidence: 81%

Fundamentals of Superior Properties in Bulk NanoSPD Materials

Valiev

Estrin

Horita

et al. 2015

Materials Research Letters

301

136

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Bulk nanoSPD materials are materials with nanostructural features, such as nanograins, nanoclusters, or nanotwins, produced by severe plastic deformation (SPD) techniques. Such nanostructured materials are fully dense and contamination free and in many cases they have superior mechanical and functional properties. Here, we provide a critical overview of such materials, with a focus on the fundamentals for the observed extraordinary properties. We discuss the unique nanostructures that lead to the superior properties, the underlying deformation mechanisms, the critical issues that remain to be investigated, future research directions, and the application potential of such materials.

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“…A strong increase in hardness upon low temperature annealing has been reported for various NC metals and can potentially be explained via dislocation annihilation, since in NC metals there is an abundance of grain boundaries acting as dislocations sinks during annealing. In order to realize plastic deformation after annealing the activation of new dislocations sources might be necessary, which requires high stresses compared to the as‐processed state . Another explanation in the literature for the observed hardening is the segregation of solutes to the grain boundaries .…”

Section: Discussionmentioning

confidence: 99%

Phase Decomposition of a Single‐Phase AlTiVNb High‐Entropy Alloy after Severe Plastic Deformation and Annealing

Schuh¹,

Völker²,

Maier–Kiener³

et al. 2017

Adv Eng Mater

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An equiatomic AlTiVNb high-entropy alloy is deformed by high pressure torsion inducing a nanocrystalline microstructure. The samples then are subjected to isochronal heat treatments between 300 C and 1000 C. The hardness increase from %7.4 GPa for the as-processed state to 10.4 GPa for an annealing temperature of 700 C, while for higher temperatures the hardness starts to decrease. Furthermore, the reduced modulus increases after annealing treatments as well. It will be shown that the unusual annealing response can be related to the formation of intermetallic phases creating a multi-phase nanocomposite material during annealing. The results give new insights into the thermodynamic stability of this alloy, which are also relevant for coarser-grained microstructures.

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Increasing the strength of nanocrystalline steels by annealing: Is segregation necessary?

Cited by 102 publications

References 35 publications

Recrystallization and grain growth of a nano/ultrafine structured austenitic stainless steel during annealing under high hydrostatic pressure

Recrystallization and grain growth of a nano/ultrafine structured austenitic stainless steel during annealing under high hydrostatic pressure

Fundamentals of Superior Properties in Bulk NanoSPD Materials

Phase Decomposition of a Single‐Phase AlTiVNb High‐Entropy Alloy after Severe Plastic Deformation and Annealing

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