Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

A significant increase in the research activity dedicated to high manganese TWIP steels has occurred during the past five years, motivated by the breakthrough combination of strength and ductility possessed by these alloys. Here a review of the relations between microstructure and mechanical properties is presented focusing on plasticity mechanisms, strain-hardening, yield stress, texture, fracture and fatigue. This summarized knowledge explains why TWIP steel metallurgy is currently a topic of great practical interest and fundamental importance. Finally, this publication indicates some of the main avenues for future investigations required in order to sustain the quality and the dynamism in this field.

High manganese austenitic twinning induced plasticity steels: A review of the microstructure properties relationships

Twinning-induced plasticity (TWIP) steels

Microstructure evolution and critical stress for twinning in the CrMnFeCoNi high-entropy alloy

Reasons for the superior mechanical properties of medium-entropy CrCoNi compared to high-entropy CrMnFeCoNi

On the mechanism of twin formation in Fe–Mn–C TWIP steels

http://ematweb.cmi.ua.ac.be/emat/pdf/1656.pdf

On the relationship between the twin internal structure and the work-hardening rate of TWIP steels

High-manganese austenitic TWIP steels exhibit very high strength and elongation before necking. The peculiarity of these steels is that mechanical twins form during straining due to their low stacking fault energy (SFE). These twins are usually thought to have a huge impact on the outstanding properties of the materials, either by bringing about a dynamic Hall & Petch effect and/or a composite effect. In this study, the appearance of mechanical twins during tensile straining is investigated for a Fe-20%Mn-1.2%C TWIP steel. The twinning rate was estimated by means of point counting analysis on EBSD micrographs at different strain levels. The reliability of this method is first thoroughly discussed. It is then shown that there exists a first order relationship between this twinning rate and the work hardening rate. © 2012 Elsevier B.V..

On the relationship between work hardening and twinning rate in TWIP steels

When strained in tension, high-manganese austenitic TWIP steels achieve very high strength and elongation before necking. They also present serrated flow within a certain range of temperatures and strain rates. A consequence of this jerky flow is the appearance of strain localisation in the form of narrow deformation bands apparent on the surface of the sample. This phenomenon arises from the dynamic interaction between solute atoms and mobile dislocations, otherwise known as dynamic strain ageing (DSA). In this study, the heterogeneous deformation of a Fe-20wt.%Mn-1.2wt.%C grade has been investigated at room temperature and at different strain rates by means of digital image correlation (DIC) for spatially resolved strain measurements made in situ during tensile tests. Simple tensile tests have also been conducted at different temperatures in order to investigate the evolution of the type of serrations and their influence on the bulk mechanical properties. The results of tests performed at room temperature and at two different strain rates, indicate that the plasticity is entirely governed by the appearance of localised deformation bands, similar to those observed in materials that exhibit the Portevin-Le Chatelier (PLC) effect. However, no critical strain for the onset of the phenomenon could be determined. The origin of these observations is discussed in this paper. It is proposed that the mode of propagation of the bands is dependent on the strain rate and the strain level. Moreover, it is shown that the band propagation is well correlated with the different types of serrations appearing on the stress-strain curve. These results match the characteristics of a classical DSA effect and help to shed light on the remarkable properties achieved by this material. (C) 2010 Elsevier B.V. All rights reserved.

Krystel Renard

Papers

On the mechanism of twin formation in Fe–Mn–C TWIP steels

On the relationship between the twin internal structure and the work-hardening rate of TWIP steels

On the relationship between work hardening and twinning rate in TWIP steels

Characterisation of the Portevin-Le Châtelier effect affecting an austenitic TWIP steel based on digital image correlation

Crystal plasticity modeling of texture development and hardening in TWIP steels