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

Magnetron sputtering: a review of recent developments and applications

Premises of creation of Internet portal designed to provide access to participants of educational and scientific process for the joint creation, consolidation, concentration and rapid spreading of educational and scientific information resources in its own depository are considered. CMS-based portal content management systems’ potentiality is investigated. Architecture for Internet portal of MES of Ukraine’s information resources is offered.

Створення порталу інформаційно-довідкових ресурсів міністерства освіти і науки україни

Abstract The historical background, research development, and the state-of-the-art of finite time thermodynamic theory and applications are reviewed from the point of view of both physics and engineering. The emphasis is on the performance optimization of thermodynamic processes and devices with finite-time and/or finite-size constraints, including heat engines, refrigerators, heat pumps, chemical reactions and some other processes, with respect to the following aspects: the study of Newton's law systems, an analysis of the effect of heat resistance and other irreversible loss models on the performance, an analysis of the effect of heat reservoir models on the performance, as well as the application for real thermodynamic processes and devices. It is pointed out that the generalized thermodynamic optimization theory is the development direction of finite thermodynamics in the future.

Finite Time Thermodynamic Optimization or Entropy Generation Minimization of Energy Systems

Materials, technological status, and fundamentals of PEM fuel cells – A review

The surface of low alloy steel (En40B) has been engineered in the plasma of a glow discharge via plasma nitriding and ion plating of titanium nitride (TiN) coatings on the nitrided substrates with the purpose of enhancing the surface properties and fatigue strength. The nitriding response of the steel has been accessed by the evaluation of phase composition, layer thickness, hardness profile, residual stresses and nitrogen and carbon distributions. The wear and fatigue characteristics of the plasma-nitrided steel have been investigated and simple models have been developed to describe the influence of such properties as depth and strength of the nitrided case on the fatigue limit and load-bearing capacity of the nitrided steel. In order to further improve the tribological properties and load-bearing capacity of the low alloy steel, a duplex plasma surface-engineering technique has been developed. This is achieved by plasma nitriding the steel first so as to produce a thick, strong subsurface and then depositing a thin, hard and wear-resistant TiN coating on the nitrided substrate by ion plating. Dry-sliding wear tests demonstrated that the duplex-treated steel, i.e. the TiN coating-nitrided steel composite, not only exhibited enhanced wear resistance over the as-nitrided steel (by a factor of 2–8) but also had much higher load-bearing capacity than the TiN coating on unnitrided steel. Optimization of the coating-substrate combination can be achieved by correct control of the plasma-nitriding, surface preparation and ion-plating processes.

Plasma surface engineering of low alloy steel

The nitrided layers produced by low temperature (400–500 °C) plasma nitriding on austenitic stainless steels, AISI 316, 304 and 321, have been characterised by X-ray diffraction, in conjunction with metallographic and chemical composition profile analysis. The thin, hard and corrosion resistant layers exhibited similar X-ray diffraction patterns, but the positions of the major diffraction peaks varied with nitriding temperature and nitrogen concentration profile. The low temperature nitrided layers are predominantly composed of a phase with a face centred cubic (fcc) structure, which is named “S” phase. However, the positions of the diffraction peaks from the “S” phase deviated in a systematic way from those for an ideal fcc lattice. Detailed analysis of the deviation suggested that very high compressive residual stresses and stacking faults were formed in the layers, resulting in a highly distorted and disordered fcc structure. The lattice parameter of the distorted and disordered “S” phase was found to increase with increasing nitrogen concentration.

X-ray diffraction characterisation of low temperature plasma nitrided austenitic stainless steels

Realising the potential of duplex surface engineering

Stainless steel is one of the most popular materials used for selective laser melting (SLM) processing to produce nearly fully dense components from 3D CAD models. The tribological and corrosion properties of stainless steel components are important in many engineering applications. In this work, the wear behaviour of SLM 316L stainless steel was investigated under dry sliding conditions, and the corrosion properties were measured electrochemically in a chloride containing solution. The results show that as compared to the standard bulk 316L steel, the SLM 316L steel exhibits deteriorated dry sliding wear resistance. The wear rate of SLM steel is dependent on the vol.% porosity in the steel and by obtaining full density it is possible achieve wear resistance similar to that of the standard bulk 316L steel. In the tested chloride containing solution, the general corrosion behaviour of the SLM steel is similar to that of the standard bulk 316L steel, but the SLM steel suffers from a reduced breakdown potential and is more susceptible to pitting corrosion. Efforts have been made to correlate the obtained results with porosity in the SLM steel.

Yong Sun

Papers

Plasma surface engineering of low alloy steel

X-ray diffraction characterisation of low temperature plasma nitrided austenitic stainless steels

Realising the potential of duplex surface engineering

Sliding Wear Characteristics and Corrosion Behaviour of Selective Laser Melted 316L Stainless Steel

Thick rutile layer on titanium for tribological applications