The current understanding of the fundamentals of recrystallization is summarized. This includes understanding the as-deformed state. Several aspects of recrystallization are described: nucleation and growth, the development of misorientation during deformation, continuous, dynamic, and geometric dynamic recrystallization, particle effects, and texture. This article is authored by the leading experts in these areas. The subjects are discussed individually and recommendations for further study are listed in the final section.

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Current issues in recrystallization: a review

A significant increase in the research activity dedicated to high manganese TWIP steels has occurred during the past five years, motivated by the breakthrough combination of strength and ductility possessed by these alloys. Here a review of the relations between microstructure and mechanical properties is presented focusing on plasticity mechanisms, strain-hardening, yield stress, texture, fracture and fatigue. This summarized knowledge explains why TWIP steel metallurgy is currently a topic of great practical interest and fundamental importance. Finally, this publication indicates some of the main avenues for future investigations required in order to sustain the quality and the dynamism in this field.

High manganese austenitic twinning induced plasticity steels: A review of the microstructure properties relationships

Welding Metallurgy of

Twinning-induced plasticity (TWIP) steels

The purpose of the present contribution is to review the current knowledge about the relationship between the micro-structure of cold rolled intercritically annealed low alloy TRIP-aided sheet steels and their mechanical properties from a materials engineering point of view. The focus is on their production in existing industrial lines and on their application in the manufacture of passenger cars with a body-in-white which offers an improved passive safety. The review aims to make clear that although low alloy TRIP-aided sheet steel is by now starting to be an established structural material in BIW manufacturing, there is still room for the further optimization of the composition and the processing. In addition, there are still a number of problems related to their physical metallurgy that require a better fundamental understanding.

Structure–properties relationship in TRIP steels containing carbide-free bainite

Aqueous sodium silicate solutions are commonly used in pretreatments of aluminium alloys as cleaners and corrosion inhibitors. Silicate films are a promising alternative for corrosion protection and are able to confer high hydrophilicity to the metal surface. An interaction mechanism of soluble sodium silicates with anodic alumina was proposed in previous publications, where the sodium cation acts as ‘bridging’ element between the silicate anions and the anodic oxide. In this work, this model of interaction is extended by considering the effect of different types of alkali cations. Porous anodized aluminum oxides were silicate treated by dipping in water-based silicate solutions of different monovalent cations, namely lithium, sodium and potassium. The surface modifications occurring on the oxide layer during immersion in solution are studied as a function of the type of cation at ratio SiO2/M2O = 1 (M = Li, Na, K) at two different temperatures of the silicate solution (30 °C and 70 °C). The morphological changes occurring on the oxide surface during immersion are observed by field emission scanning electron microscopy, while the reactions happening at the anodic alumina surface are studied by monitoring the open circuit potential as a function of time. The attack of the oxide layer at low silicon-to-cation ratio is quantified by means of wavelength dispersive X-ray fluorescence. Copyright © 2013 John Wiley & Sons, Ltd.

Influence of the type of alkali metal cation on the interaction of soluble silicates with porous anodic alumina

An Fe-2%Si alloy, which was designed for electromagnetic applications was submitted to a series of plane strain compression (PSC) tests with reductions of 25, 35 and 75% at temperatures varying from 800 to 1,100°C and at a constant engineering strain rate corresponding to a constant cross velocity of 20 mm/s. The initial structure of the material displayed nearly equi-axed grains with an average size of 80 μm. The as-received texture was characterised by a nearly random cube fibre (//ND) with a relatively weak maximum on the rotated cube component ({001}). After deformation the samples were water quenched in order to avoid post-process static recrystallization events. The microstructures were analysed by orientation imaging microscopy (OIM) revealing that the zone of PSC was restricted to the central layers of the sample but minimally covering 50% of the sample thickness. After deformation at 800°C the conventional lamellar deformation structures were observed on the sections perpendicular to the transverse direction of PSC. At higher deformation temperatures the structure was of a bimodal nature consisting of lamellar deformation bands and equi-axed small grains. The volume fraction of these small equi-axed grains increased from 19.9% after 75%reduction at 800°C to 67.8% after 75% reduction at 1.100°C. After 75% reduction the equi-axed grains exhibited an average size of 10 μm which represents a strong grain refinement with respect to the initial size of 80 μm prior to PSC. Ferrite Silicon steels undergo extensive dynamic recovery during hot working. Dynamic recrystallization (DRX), though, has not yet been reported for these alloys although the present data suggest that a DRX mechanism might be responsible for the remarkable grain refinement after relatively low amounts of strain applied at high temperatures.

Grain refinement by high temperature plane-strain compression of Fe-2%Si steel

Microstructure, Anisotropy and Formability Evolution of an Annealed AISI 430 Stainless Steel Sheet

The present paper presents an overview of present and future tools which can be used by the steel manufacturer in order to control the texture of the finished sheet product. The major solid-state-transformation processes (phase transformation, plastic deformation and recrystallisation) playing a role during thermo-mechanical processing will be addressed. The physical mechanisms that give rise to the appearance of specific texture components will be discussed in detail. In addition to current state-of-the-art process technology the potential of innovative processes will be described such as accumulative roll bonding (ARB). The present paper will also pay attention to the particular role of surface textures as an additional degree of freedom allowing to control the sheet texture with the potential to enhance the {001} or {110} fibre textures for magnetic applications.

Physical Metallurgical Aspects of Texture Control by Thermo-Mechanical Processing of Low-Carbon Steel Sheet

The cold rolling and annealing texture formation has been investigated in electro deposited pure iron which has an extremely sharp and isotropic //ND fiber. Regardless of cold rolling reduction, {111} intensified texture is formed after cold rolling. Similar texture remains after recrystallization in 65% cold rolled material while {111} type texture forms in 80% and 90% cold rolled ones. The recrystallized grains at the stage of 5% recrystallization have {111} orientation in 65% cold rolled sheet, whereas {111} is observed in 80% cold rolled one. From this aspect, it is considered that the nucleation orientation plays an important role in the recrystallization texture formation. In the meanwhile, the growth of the recrystallized nuclei is also supposed to affect the recrystallization texture formation. The nuclei with {111} orientation in lightly cold rolled sheet are easier to consume the deformed matrix than they do in heavily cold rolled sheets because their frequency to encounter a deformed grain with nearly the same orientation is much smaller in lightly cold rolled specimen, which can result in a large mobility for growth. Cross cold rolling makes cold rolling texture rather homogeneous //ND fiber, which gives rise to an almost homogeneous //ND fiber after annealing.

Influence of Cold Rolling Reduction and Cross Rolling on Recrystallization Texture Formation in Electro Deposited Pure Iron with a Sharp and Homogeneous //ND Fiber

Leo A.I. Kestens

Papers

Influence of the type of alkali metal cation on the interaction of soluble silicates with porous anodic alumina

Grain refinement by high temperature plane-strain compression of Fe-2%Si steel

Microstructure, Anisotropy and Formability Evolution of an Annealed AISI 430 Stainless Steel Sheet

Physical Metallurgical Aspects of Texture Control by Thermo-Mechanical Processing of Low-Carbon Steel Sheet

Influence of Cold Rolling Reduction and Cross Rolling on Recrystallization Texture Formation in Electro Deposited Pure Iron with a Sharp and Homogeneous //ND Fiber