다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

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

생체의 모델링과 Simulation

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

Steels for bearings

Recent work has shown that bainitic ferrite plates produced by transformation at low temperatures can be as thin as 20 nm with a hardness in excess of 650 HV. However, it may take several days in order to achieve the required degree of transformation at low temperatures. In this work we report methods for accelerating the rate of reaction without compromising strength.

/pdf/acceleration-of-low-temperature-bainite-39z5lcrelk.pdf

Acceleration of Low-temperature Bainite

It is demonstrated that in a high-carbon steel where carbide precipitation is suppressed, bainite can be obtained by isothermal transformation at temperatures as low as 200°C. The time taken for nucleation at this temperature can be many days, but the transformation results in the growth of extremely thin platelets of bainite, so thin that the hardness of the resulting steel can be greater than 600 HV.

/pdf/development-of-hard-bainite-o1p842aw4t.pdf

Development of Hard Bainite

https://digital.csic.es/bitstream/10261/34321/1/Acta_2007_Caballero.pdf

Atomic scale observations of bainite transformation in a high carbon high silicon steel

The authors acknowledge financial support from the
Spanish Ministerio de Educacion y Ciencia for the financial
support in the form of Ramon y Cajal contracts (RyC 2002
and 2004 respectively). Some of this work was carried out
under the auspices of an EPSRC/MOD sponsored project
on bainitic steels at the University of Cambridge; we are
extremely grateful for this support over a period of three
years. The authors are extremely grateful to Prof. H. K. D.

/pdf/ultra-high-strength-bainitic-steels-4ebzho4kvs.pdf

Ultra-high-strength Bainitic Steels

In high-carbon, silicon-rich steels it is possible to obtain a very fine bainitic microstructure by transformation at low temperatures (200– 300 � C). This microstructure consists of slender ferrite plates, with thicknesses of several tens of nm, in a matrix of retained austenite. Whereas strength is mainly provided by to the fine scale of the ferrite plates (stronger phase), ductility is mostly controlled by the retained austenite (softer phase). Further improvement in ductility is achieved by strain induced transformation of austenite to martensite, the so called TRIP effect. In order to take full advantage of this effect, the mechanical stability of the austenite, i.e., its capability to transform to martensite under strain, must not be too low nor excessively high. Two main aspects of the mechanical stability of the retained austenite, morphology and chemical composition, have been studied to determine the role that these play on the ductility behaviour of the bainitic steels studied. It is suggested that the chemical composition has the strongest effect on the ductility of these new high strength alloys.

/pdf/the-role-of-retained-austenite-on-tensile-properties-of-4ce64j3kwr.pdf

Carlos Garcia-Mateo

Papers

Acceleration of Low-temperature Bainite

Development of Hard Bainite

Atomic scale observations of bainite transformation in a high carbon high silicon steel

Ultra-high-strength Bainitic Steels

The Role of Retained Austenite on Tensile Properties of Steels with Bainitic Microstructures