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

The present invention provides a heterocyclic compound and an organic light-emitting device including the heterocyclic compound. The organic light-emitting devices using the heterocyclic compounds have high-efficiency, low driving voltage, high luminance and long lifespan.

Organic light-emitting device

Gibbs-Thomson effects in phase transformations

A new model for the evolution of the precipitate structure derived by means of application of the thermodynamic extremum principle is presented. The model describes the evolution of the radii and of the chemical composition of individual precipitates of different phases in the multi-component system. In connection with a proper theory of nucleation, the model is able to describe the evolution of the precipitate structure in the classical stages of nucleation, growth and coarsening as well as interaction of precipitates of different phases, of different chemical composition and of different sizes via diffusion in the matrix.

Modelling of kinetics in multi-component multi-phase systems with spherical precipitates I. – Theory

Development of high strength ferritic steel for interconnect application in SOFCs

A high-strength cold-rolled steel sheet includes, by mass %, C: 0.10% to 0.40%, Mn: 0.5% to 4.0%, Si: 0.005% to 2.5%, Al: 0.005% to 2.5%, Cr: 0% to 1.0%, and a balance of iron and inevitable impurities, in which an amount of P is limited to 0.05% or less, an amount of S is limited to 0.02% or less, an amount of N is limited to 0.006% or less, the microstructure includes 2% to 30% of retained austenite by area percentage, martensite is limited to 20% or less by area percentage in the microstructure, an average particle size of cementite is 0.01 μm to 1 μm, and 30% to 100% of the cementite has an aspect ratio of 1 to 3.

High-strength cold-rolled steel sheet and method of manufacturing thereof

PROBLEM TO BE SOLVED: To provide a TRIP type hot dip galvanized high strength steel sheet and a hot dip zincing high strength steel sheet each having a uniform structure and excellent corrosion resistance and formability, and to provide methods for producing them. SOLUTION: The hot dip galvanized high strength steel sheet is obtained by applying hot dip galvanizing to a steel sheet having a steel composition comprising, by mass, 0.05 to 0.25% C, ≤2.0% Si, 0.8 to 3% Mn, 0.0010 to 0.1% P, 0.0010 to 0.05% S, 0.0010 to 0.010% N and 0.01 to 2.0% Al, and the balance iron with inevitable impurities, and whose structure comprises retained austenite having a mean carbon content of ≥0.9% by ≥3%, and in which Mn micro-segregation in the range of 1/8t to 3/8t of the sheet thickness t lies in the range satisfying inequality (1): 0.10≥σ/Mn (1); wherein Mn denotes its additional amount; and σ denotes the standard deviation in Mn micro-segregation measurement. COPYRIGHT: (C)2007,JPO&INPIT

Hot dip galvanized high strength steel sheet and hot dip zincing high strength steel sheet having excellent corrosion resistance and formability, and method for producing them

PROBLEM TO BE SOLVED: To realize a high strength steel sheet which has excellent formability and chemical convertibility, and to realize a production method therefor on an industrial scale. SOLUTION: The high strength steel sheet having excellent formability and chemical convertibility has a composition containing, by mass, 0.01 to 0.30% C, 0.005 to 0.2% Si, 0.1 to 2.2% Mn, 0.001 to 0.06% P, 0.001 to 0.01% S, 0.0005 to 0.01% N, and 0.25 to 1.8% Al, and the balance Fe with inevitable impurities, and in which the mass% of Si, Mn, and Al also saatisfy the following inequality (A), and has a metallic structure containing ferrite and martensite: (0.0012×[TS objective value]-0.29-[Si])/1.45<Al<1.5-3*[Si] (A); wherein [TS objective value] is the set value of the strength of the steel sheet with Mpa as a unit, and [Si] is the mass% of Si. COPYRIGHT: (C)2003,JPO

High strength steel sheet having excellent formability and chemical convertibility and production method therefor

PROBLEM TO BE SOLVED: To achieve a hot dip galvanized high strength steel sheet having excellent platability and formability and a method for producing the same on an industrial scale. SOLUTION: The hot dip galvanized high strength steel sheet has a composition comprising, by mass, 0.07 to 0.22% C, 0.005 to 1.0% Si, 1.5 to 2.8% Mn, 0.001 to 0.1% P, 0.001 to 0.01% S, 0.0005 to 0.01% N, 0.02 to 1.0% Al, ≤0.3% Mo and ≤0.5% Cr, and the balance Fe with inevitable impurities, and has a microstructure where the area ratio of ferrite is 20 to 70%, the area ratio of retained austenite is 1 to 5% and the area ratio of martensite is 20 to 70%, and the balance bainite, and also satisfies inequalities of martensite fraction≥0.07×[TS target value]-40, ferrite fraction≥(100-[martensite fraction])×0.8-20, and (0.0012×[TS target value]-0.29)/3<[Al]+0.7[Si]<1.4. COPYRIGHT: (C)2010,JPO&INPIT

Hot dip galvanized high strength steel sheet having excellent formability, and method for producing the same

The present invention provides: a high-strength high-ductility hot-dip galvanized steel sheet and hot-dip galvannealed steel sheet having high fatigue resistance and corrosion resistance; a high-strength hot-dip galvanized steel sheet excellent in ductility, which improves non-plating defects and plating adhesion after severe deformation, and a method of producing the same; a high-strength and high-ductility hot-dip galvanized steel sheet having high fatigue resistance and corrosion resistance; a high-strength hot-dip galvanized steel sheet and hot-dip galvannealed steel sheet having superiorappearance and workability, which suppresses the generation of non-plating defects, and a method of producing the same; and a high-strength hot-dip galvannealed steel sheet and a high-strength hot-dip galvanized steel sheet, which suppress non-plating defects and surface defects and have both corrosion resistance, in particular corrosion resistance in an environment containing chlorine ion, and high ductility, and a method of producing the same.

Nobuhiro Fujita

Papers

High-strength cold-rolled steel sheet and method of manufacturing thereof

Hot dip galvanized high strength steel sheet and hot dip zincing high strength steel sheet having excellent corrosion resistance and formability, and method for producing them

High strength steel sheet having excellent formability and chemical convertibility and production method therefor

Hot dip galvanized high strength steel sheet having excellent formability, and method for producing the same

Hot-dip galvanized thin steel sheet, thin steel sheet processed by hot-dip galvanized layer, and a method of producing the same