J. Appl. Cryst.の発刊に際して

Dual-phase (DP) steel is the flagship of advanced high-strength steels, which were the first among various candidate alloy systems to find application in weight-reduced automotive components. On the one hand, this is a metallurgical success story: Lean alloying and simple thermomechanical treatment enable use of less material to accomplish more performance while complying with demanding environmental and economic constraints. On the other hand, the enormous literature on DP steels demonstrates the immense complexity of microstructure physics in multiphase alloys: Roughly 50 years after the first reports on ferrite-martensite steels, there are still various open scientific questions. Fortunately, the last decades witnessed enormous advances in the development of enabling experimental and simulation techniques, significantly improving the understanding of DP steels. This review provides a detailed account of these improvements, focusing specifically on (a) microstructure evolution during processing, (b) exp...

An Overview of Dual-Phase Steels: Advances in Microstructure-Oriented Processing and Micromechanically Guided Design

The major scientific and technological advances and breakthroughs of advanced high strength steels (AHSS) were achieved due to the strong demands of automotive industry. The development of AHSS began in the early 1980s with the aim of improving passenger safety and weight-saving. The present paper presents the driving forces and logic of development of various AHSS for automotive applications since 1980s. The importance of crash performance, weight-saving, formability, and rigidity are critically reviewed for the development of new steel grades for automotive applications. The logical sequences of the development of dual phase (DP) steel, transformation induced plasticity (TRIP) steels, tempered DP steels, complex phases (CP) steels, Ferrite-Bainite steels, hot-stamping technology, twinning induced plasticity (TWIP) steels, Quench and Partitioning (Q&P) steels, Medium Mn steels, and steels–polymer composites are presented.

Driving Force and Logic of Development of Advanced High Strength Steels for Automotive Applications

Mechanisms of sliding wear of metals and alloys at elevated temperatures

Multiaxial high-cycle fatigue criterion and life prediction for metals

A modeling approach to account for the effect of deformation on the austenite to ferrite transformation is described. In this approach the stored energy of deformation resulting from the formation of a dislocation substructure is considered to result in an elevation of the driving force for transformation. A scheme which accounts for the competition between softening and transformation processes is also described. Model data illustrating the effects of discrete dislocations and cell structures, with and without concurrent recovery are presented. Comparison of modeled and experimental transformation curves indicates that deformation affects the transformation principally via a reduction in the undercooling required for nucleation rather than via an acceleration of the growth kinetics.

https://www.jstage.jst.go.jp/article/isijinternational1989/41/9/41_9_1028/_pdf

The Effect of Plastic Deformation of Austenite on the Kinetics of Subsequent Ferrite Formation

http://ematweb.cmi.ua.ac.be/emat/pdf/1757.pdf

Characterization of NbC and (Nb, Ti)N nanoprecipitates in TRIP assisted multiphase steels

Quantification of the evolution of the 3D intermetallic structure in a 6005A aluminium alloy during a homogenisation treatment

Dual-phase (DP) steels are generally characterized by the combination of high strength with good ductility, but some formability characteristics of these steels are low compared to other steel classes. In particular, stretched edge ductility and bendability are poor by comparison with other less ductile strip steel classes such as complex-phase (CP) steels. This paper describes the effect of short time tempering of the order of few seconds to few minutes on the mechanical properties of two cold rolled and hot-dip galvanised dual-phase (DP) steels. The uni-axial tensile characteristics, hole-expansivity, Erichsen cupping height and bendability were assessed after tempering at temperatures between 200 and 450 °C for relatively short time scales up to 10 min. The short tempering treatments significantly changed the character of the DP steel leading to a decrease in tensile elongation and an increase in hole-expansitivity and bendability. The properties observed in tempered DP steels where found to be closely comparable to those expected for CP steels. Microstructural analyses using the SEM showed carbide precipitation within the martensite and ferrite that increased with tempering.

David Neal Hanlon

Papers

The Effect of Plastic Deformation of Austenite on the Kinetics of Subsequent Ferrite Formation

Characterization of NbC and (Nb, Ti)N nanoprecipitates in TRIP assisted multiphase steels

Quantification of the evolution of the 3D intermetallic structure in a 6005A aluminium alloy during a homogenisation treatment

Effects of tempering on the mechanical properties of high strength dual-phase steels

The rolling/sliding wear response of conventionally processed and spray formed high chromium content cast iron at ambient and elevated temperature