The Aging and Tempering of Iron-Nickel-Carbon Martensites

Sherman, Andrew M.; Eldis, G. T.; Cohen, Morris

doi:10.1007/bf02659847

Cited by 71 publications

(24 citation statements)

References 26 publications

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“…They do not have the composition of Fe 4 C, as suggested by Sherman et.al. [20], but are close to the composition of FeC 8 . The density of clusters and fine precipitates is an order of magnitude higher than in the martensite after TMP [19,21].…”

Section: Effect Of Bake Hardening On Martensite In Trip Steelsupporting

confidence: 56%

Observations of decomposition of martensite during heat treatment of steels using atom probe tomography

Pereloma

Ringer

Timokhina

et al. 2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

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Abstract. The decomposition of martensite during tempering or ageing is an important phenomenon as it leads to changes in the mechanical properties. These changes could take place during both steel manufacturing or in-service. Thus, their understanding is required to predict the material performance. Recent advances in the development of local electrode atom probes has led to a significant increase in the analysed volume of material (up to 100 millions of atoms) and at the same time reduced the acquisition times. This allows improvement in data statistics when investigating fine nanoscale features, such as solute segregation, clustering and ultrafine precipitation. Selected results of atom probe studies on the decomposition of martensite from bake hardening of a pre-strained Transformation Induced Plasticity (TRIP) steel and ageing of FeNiTiMnAl maraging steel are presented.

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Section: Effect Of Bake Hardening On Martensite In Trip Steelsupporting

confidence: 56%

Observations of decomposition of martensite during heat treatment of steels using atom probe tomography

Pereloma

Ringer

Timokhina

et al. 2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

View full text Add to dashboard Cite

show abstract

“…1,2,22,23) The low n-value (0.39) obtained for stage II of tempering on the other hand strongly suggests that the volume change is diffusion-controlled. In a study devoted to the tempering of Fe-Ni-C-martensite, Sherman et al 24) proposed that Fediffusion along dislocations is the rate-determining step for h-carbide precipitation. The observed activation energies for this stage are (120-127 kJ/mol) indeed close to the activation energy associated with dislocation pipe-diffusion of iron, 134 kJ/mol 2 .…”

Section: Isothermal Dilatometric Testsmentioning

confidence: 99%

Tempering Kinetics of the Martensitic Phase in DP Steel

2006

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The increase in the yield stress of dual phase (DP) steels, resulting from the static strain ageing phenomenon, commonly referred to as bake hardening (BH), gives an important contribution to the additional in-service strength of outer auto body parts, e.g. with respect to the dent resistance of the components made with DP steel. In order to understand this large BH effect, the role of the different constituents of the DP steel during this process needs to be considered. The various stages of tempering phenomena taking place in the martensite phase were investigated in detail by means of precision dilatometry and X-Ray Diffraction (XRD). The succession of the various tempering reactions that are characterised by typical volume changes was determined using both constant heating rate and isothermal dilatometric tests. The measurements made it possible to distinguish five distinct stages of structural changes during tempering: (I) the redistribution of carbon atoms, (II) the precipitation of h-or e-carbide, (III) the formation of Hägg-carbide, (IV) the decomposition of retained austenite, and (V) the transformation of transition carbides to cementite.KEY WORDS: bake hardening; dual phase steel; tempering; martensite; XRD, dilatometry.

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“…As a result of tempering, carbides precipitate in hard, brittle martensite that is supersaturated in carbon, leading to improved ductility and fracture toughness. [1][2][3][4][5][6] It is well accepted that there are four stages of tempering of ferrous martensite: (1) formation of transition carbide, presumably e-carbide, Fe 2.4 C, or g-carbide, Fe 2 C; (2) decomposition of retained austenite into ferrite and cementite; (3) replacement of transition carbide by cementite, Fe 3 C; and (4) secondary hardening manifested by the development of alloy carbides in alloy steels. [1][2][3][4][5][6] However, prior to tempering of martensite, room-temperature aging or autotempering of martensite formed at high temperatures on quenching takes place.…”

mentioning

confidence: 99%

“…[1][2][3][4][5][6] It is well accepted that there are four stages of tempering of ferrous martensite: (1) formation of transition carbide, presumably e-carbide, Fe 2.4 C, or g-carbide, Fe 2 C; (2) decomposition of retained austenite into ferrite and cementite; (3) replacement of transition carbide by cementite, Fe 3 C; and (4) secondary hardening manifested by the development of alloy carbides in alloy steels. [1][2][3][4][5][6] However, prior to tempering of martensite, room-temperature aging or autotempering of martensite formed at high temperatures on quenching takes place. [3,4,[7][8][9][10] This process is associated with carbon segregation to dislocations and twin boundaries, to and from retained austenite films, the formation of a periodic tweed structure consisting of carbon modulations in Ni-containing martensites, and carbon clustering before the precipitation of iron-carbide.…”

mentioning

confidence: 99%

On the Decomposition of Martensite during Bake Hardening of Thermomechanically Processed Transformation-Induced Plasticity Steels

Pereloma

Miller

Timokhina

2008

Metall Mater Trans A

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Thermomechanically processed (TMP) CMnSi transformation-induced plasticity (TRIP) steels with and without additions of Nb, Mo, or Al were subjected to prestraining and bake hardening. Atom probe tomography (APT) revealed the presence of fine C-rich clusters in the martensite of all studied steels after the thermomechanical processing. After bake hardening, the formation of iron carbides, containing from 25 to 90 at. pct C, was observed. The evolution of iron carbide compositions was independent of steel composition and was a function of carbide size.

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The Aging and Tempering of Iron-Nickel-Carbon Martensites

Cited by 71 publications

References 26 publications

Observations of decomposition of martensite during heat treatment of steels using atom probe tomography

Observations of decomposition of martensite during heat treatment of steels using atom probe tomography

Tempering Kinetics of the Martensitic Phase in DP Steel

On the Decomposition of Martensite during Bake Hardening of Thermomechanically Processed Transformation-Induced Plasticity Steels

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