This article presents an overview of the developments in stainless steels made since the 1990s. Some of the new applications that involve the use of stainless steel are also introduced. A brief introduction to the various classes of stainless steels, their precipitate phases and the status quo of their production around the globe is given first. The advances in a variety of subject areas that have been made recently will then be presented. These recent advances include (1) new findings on the various precipitate phases (the new J phase, new orientation relationships, new phase diagram for the Fe–Cr system, etc.); (2) new suggestions for the prevention/mitigation of the different problems and new methods for their detection/measurement and (3) new techniques for surface/bulk property enhancement (such as laser shot peening, grain boundary engineering and grain refinement). Recent developments in topics like phase prediction, stacking fault energy, superplasticity, metadynamic recrystallisation and the calculation of mechanical properties are introduced, too. In the end of this article, several new applications that involve the use of stainless steels are presented. Some of these are the use of austenitic stainless steels for signature authentication (magnetic recording), the utilisation of the cryogenic magnetic transition of the sigma phase for hot spot detection (the Sigmaplugs), the new Pt-enhanced radiopaque stainless steel (PERSS) coronary stents and stainless steel stents that may be used for magnetic drug targeting. Besides recent developments in conventional stainless steels, those in the high-nitrogen, low-Ni (or Ni-free) varieties are also introduced. These recent developments include new methods for attaining very high nitrogen contents, new guidelines for alloy design, the merits/demerits associated with high nitrogen contents, etc.

Recent developments in stainless steels

Pitting corrosion is localized accelerated dissolution of metal that occurs as a result of a breakdown of the otherwise protective passive film on the metal surface. This paper provides an overview of the critical factors influencing the pitting corrosion of metals. The phenomenology of pitting corrosion is discussed, including the effects of alloy composition, environment, potential, and temperature. A summary is then given of studies that have focused on various stages of the pitting process, including breakdown of the passive film, metastable pitting, and pit growth.

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Pitting Corrosion of Metals A Review of the Critical Factors

Introduction 1. Aqueous Corrosion 2. Environments and Application Examples 3. high-Temperature Corrosion 4. Modeling, Life Prediction, and Computer Applications 5. Corrosion Failures 6. Corrosion Maintenance Through Inspection And Monitoring 7. Acceleration and Amplification of Corrosion Damage 8. Materials Selection 9. Protective Coatings 10. Corrosion Inhibitors 11. Cathodic Protection 12. Anodic Protection

/pdf/handbook-of-corrosion-engineering-2rocvbvrpb.pdf

Handbook of Corrosion Engineering

Laser melting (LM), with a focused Nd: YAG laser beam, was used to form solid bodies from a 316L austenite stainless steel powder. The microstructure, phase content and texture of the LM stainless steel were characterized and compared with conventional 316L stainless steel. The crack-free LM samples achieved a relative density of 98.6±0.1%. The XRD pattern revealed a single phase Austenite with preferential crystallite growth along the (100) plane and an orientation degree of 0.84 on the building surface. A fine columnar sub-grain structure of size 0.5 μm was observed inside each individual large grain of single-crystal nature and with grain sizes in the range of 10–100 μm. Molybdenum was found to be enriched at the sub-grain boundaries accompanied with high dislocation concentrations. It was proposed that such a sub-grain structure is formed by the compositional fluctuation due to the slow kinetics of homogeneous alloying of large Mo atoms during rapid solidification. The local enrichment of misplaced Mo in the Austenite lattice induced a network of dislocation tangling, which would retard or even block the migration of newly formed dislocations under indentation force, turning otherwise a soft Austenite to hardened steel. In addition, local formation of spherical nano-inclusions of an amorphous chromium-containing silicate was observed. The origin and the implications of the formation of such oxide nano-inclusions were discussed.

Hardened austenite steel with columnar sub-grain structure formed by laser melting

Forms of Corrosion.- Electrochemistry.- Kinetics of Activation Polarization.- Kinetics of Concentration Polarization.- Mixed Potential Theory.- Corrosivity and Passivity.- Electrometallurgy.- Cathodic Protection.- Anodic Protection.- High-temperature Corrosion.

Electrochemistry and Corrosion Science

With good pricing, high strength, as well as corrosion resistance, stainless steel is a widely used and popular choice for many applications as a rust resistant material, however many types of corrosion attack stainless steel, such as pitting and crevice corrosion, intergranular corrosion, stress-corrosion cracking, hydrogen embrittlement, general corrosion, and attack by high-temperature gases. This article reviews the corrosion mechanisms of stainless steel to understand the corrosion behavior of stainless steel which is important for the design of any application. Moreover, this article will provide a platform for selecting the suitable type of stainless steel for any application with high corrosion resistance.

A. John Sedriks

Papers

Corrosion of Stainless Steels