Carbon Redistribution in Martensite in High-C Steel: Atomic-Scale Characterization and Modelling

Song, Wenwen; Drouven, Carsten; Galindo-Nava, E.I.

doi:10.3390/met8080577

Cited by 9 publications

(4 citation statements)

References 20 publications

(45 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Carbon atoms segregate around boundaries and dislocations to form Cottrell atmospheres, which has been confirmed by 3D atom probe observations [42,49,50]. A Cottrell atmosphere decreases the strain energy produced by carbon atoms in the vicinity of a dislocation and stabilises it, so the dislocation has to break away from the atmosphere to glide further, which is the main mechanism of interactions between carbon atoms and dislocations [51].…”

Section: Dislocation Generation Caused By the Interaction With Carbon Atomsmentioning

confidence: 74%

A Unified Model for Plasticity in Ferritic, Martensitic and Dual-Phase Steels

Matsuyama

Galindo-Nava

2020

Metals

View full text Add to dashboard Cite

Unified equations for the relationships among dislocation density, carbon content and grain size in ferritic, martensitic and dual-phase steels are presented. Advanced high-strength steels have been developed to meet targets of improved strength and formability in the automotive industry, where combined properties are achieved by tailoring complex microstructures. Specifically, in dual-phase (DP) steels, martensite with high strength and poor ductility reinforces steel, whereas ferrite with high ductility and low strength maintains steel’s formability. To further optimise DP steel’s performance, detailed understanding is required of how carbon content and initial microstructure affect deformation and damage in multi-phase alloys. Therefore, we derive modified versions of the Kocks–Mecking model describing the evolution of the dislocation density. The coefficient controlling dislocation generation is obtained by estimating the strain increments produced by dislocations pinning at other dislocations, solute atoms and grain boundaries; such increments are obtained by comparing the energy required to form dislocation dipoles, Cottrell atmospheres and pile-ups at grain boundaries, respectively, against the energy required for a dislocation to form and glide. Further analysis is made on how thermal activation affects the efficiency of different obstacles to pin dislocations to obtain the dislocation recovery rate. The results are validated against ferritic, martensitic and dual-phase steels showing good accuracy. The outputs are then employed to suggest optimal carbon and grain size combinations in ferrite and martensite to achieve highest uniform elongation in single- and dual-phase steels. The models are also combined with finite-element simulations to understand the effect of microstructure and composition on plastic localisation at the ferrite/martensite interface to design microstructures in dual-phase steels for improved ductility.

show abstract

Section: Dislocation Generation Caused By the Interaction With Carbon Atomsmentioning

confidence: 74%

A Unified Model for Plasticity in Ferritic, Martensitic and Dual-Phase Steels

Matsuyama

Galindo-Nava

2020

Metals

View full text Add to dashboard Cite

show abstract

“…This observation suggests all the samples have a fully martensitic microstructure already after ESF. 100Cr6 is characterized for the precipitation of (Fe, Cr) 3 C [15,16]; these spheroidized carbides precipitate during heat treatment, enhancing the wear-resistant character of the material.…”

Section: Microhardness and Macroharndessmentioning

confidence: 99%

“…Its chemical composition is characterized by high carbon (about 1%) and moderate chromium (1.5%), responsible for the formation of iron-chromium carbides [15]. No rare or costly elements are present in this steel grade; such characteristics make the bulk 100Cr6 the most common and favorable bulk steel due to the balance between cost and mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Innovative Densification Process of a Fe-Cr-C Powder Metallurgy Steel

Gobber

Bidulská

Fais³

et al. 2021

Metals

View full text Add to dashboard Cite

In this study, the efficacy of an innovative ultra-fast sintering technique called electro-sinter-forging (ESF) was evaluated in the densification of Fe-Cr-C steel. Although ESF proved to be effective in densifying several different metallic materials and composites, it has not yet been applied to powder metallurgy Fe-Cr-C steels. Pre-alloyed Astaloy CrM powders have been ad-mixed with either graphite or graphene and then processed by ESF. By properly tuning the process parameters, final densities higher than 99% were obtained. Mechanical properties such as hardness and transverse rupture strength (TRS) were tested on samples produced by employing different process parameters and then submitted to different post-treatments (machining, heat treatment). A final transverse rupture strength up to 1340 ± 147 MPa was achieved after heat treatment, corresponding to a hardness of 852 ± 41 HV. The experimental characterization highlighted that porosity is the main factor affecting the samples’ mechanical resistance, correlating linearly with the transverse rupture strength. Conversely, it is not possible to establish a similar interdependency between hardness and mechanical resistance, since porosity has a higher effect on the final properties.

show abstract

“…This typically happens above C contents of 0.6 wt% in plain C steels, [17] with higher C contents leading to higher retained austenite fractions. [18][19][20] This has been an undesired effect in the hardening of tool steels and to the knowledge of the authors, no attempts have been made to systematically use this austenite stabilization mechanism to achieve a fully austenitic microstructure. For the use in noncorrosive H environments such as high-pressure H, such a C austenitic steel may however be beneficial, as previous reports suggest that C protects Fe and its alloys from HE.…”

Section: Introductionmentioning

confidence: 99%

A Carbon‐Stabilized Austenitic Steel with Lower Hydrogen Embrittlement Susceptibility

Khanchandani,

Zeiler,

Strobel

et al. 2023

steel research int.

View full text Add to dashboard Cite

High‐strength steels are susceptible to H‐induced failure, which is typically caused by the presence of diffusible H in the microstructure. The diffusivity of H in austenitic steels with face‐centered cubic (fcc) crystal structure is slow. The austenitic steels are hence preferred for applications in the hydrogen‐containing atmospheres. However, the fcc structure of austenitic steels is often stabilized by the addition of Ni, Mn, or N, which are relatively expensive alloying elements to use. Austenite can kinetically also be stabilized using C. Herein, an approach is applied to a commercial cold work tool steel, where C is used to fully stabilize the fcc phase. This results in a microstructure consisting of only austenite and M7C3 carbide. An exposure to H by cathodic hydrogen charging exhibits no significant influence on the strength and ductility of the C‐stabilized austenitic steel. While this material is only a prototype based on an existing alloy of different purposes, it shows the potential for low‐cost H‐resistant steels based on C‐stabilized austenite.

show abstract

Carbon Redistribution in Martensite in High-C Steel: Atomic-Scale Characterization and Modelling

Cited by 9 publications

References 20 publications

A Unified Model for Plasticity in Ferritic, Martensitic and Dual-Phase Steels

A Unified Model for Plasticity in Ferritic, Martensitic and Dual-Phase Steels

Innovative Densification Process of a Fe-Cr-C Powder Metallurgy Steel

A Carbon‐Stabilized Austenitic Steel with Lower Hydrogen Embrittlement Susceptibility

Contact Info

Product

Resources

About