Retained Austenite and the Tempering of Martensite

Matas, Sebastián Feliu; Hehemann, R. F.

doi:10.1038/187685a0

Cited by 56 publications

(37 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…If the X-ray measurement is taken to be more accurate, then the M S temperature of V c T would rise to 20°C so that martensite would not form on cooling the sample to room temperature; this does not strictly explain the discrepancy between the values of V c 0 for curves ''a'' and ''b'' illustrated in Figure 8. The explanation consistent with past experience [54] is that the carbon is not uniformly distributed, with the larger islands containing a lower concentration and hence decomposing to martensite on cooling.…”

Section: Resultssupporting

confidence: 74%

Carbide-Free Bainite: Compromise between Rate of Transformation and Properties

Khare

Lee

Bhadeshia

2010

Metall Mater Trans A

View full text Add to dashboard Cite

By identifying the relationship between the time required to obtain bainite and parameters such as the transformation temperature and carbon concentration, it has been possible to institute a design procedure that led to the desired mechanical properties and transformation characteristics. The work has also identified difficulties in the calculation of tensile elongation on the basis of a percolation model, which suggests that fracture occurs when the fraction of austenite drops below the percolation threshold in the microstructure.

show abstract

Section: Resultssupporting

confidence: 74%

Carbide-Free Bainite: Compromise between Rate of Transformation and Properties

Khare

Lee

Bhadeshia

2010

Metall Mater Trans A

View full text Add to dashboard Cite

show abstract

“…During this second step, it was unambiguously shown that carbon can diffuse from martensite to untransformed austenite, from measurements at the atomic scale [1,2]. In a seminal article in 1960 published in Nature, Matas S. and Hehemann M. F. had already shown that the tempering of martensite leads to a carbon-enriched austenite [3]. In common steels, this process is largely inhibited by carbide precipitation (the so-called tempering process).…”

Section: Introductionmentioning

confidence: 99%

Effects of Q&P Processing Conditions on Austenite Carbon Enrichment Studied by In Situ High-Energy X-ray Diffraction Experiments

Allain

Géandier

Hell³

et al. 2017

Metals

View full text Add to dashboard Cite

Abstract:We report the first ultra-fast time-resolved quantitative information on the quenching and partitioning process of conventional high-strength steel by an in situ high-energy X-ray diffraction (HEXRD) experiment. The time and temperature evolutions of phase fractions, their carbon content, and internal stresses were determined and discussed for different process parameters. It is shown that the austenite-to-martensite transformation below the martensite start temperature Ms is followed by a stage of fast carbon enrichment in austenite during isothermal holding at both 400 and 450 • C. The analysis proposed supports the concurrent bainite transformation and carbon diffusion from martensite to austenite as the main mechanisms of this enrichment. Furthermore, we give evidence that high hydrostatic tensile stresses in austenite are produced during the final quenching, and must be taken into account for the estimation of the carbon content in austenite. Finally, a large amount of carbon is shown to be trapped in the microstructure.

show abstract

“…Ko and Cottrell [5] discovered that bainite, similarly to martensite, forms with a surface relief. That inspired Matas and Hehemann [6] to propose that bainitic ferrite grows very fast, without time for diffusion of carbon. Cementite in lower bainite would then form by a subsequent precipitation of carbon from the supersaturated ferrite.…”

Section: Introductionmentioning

confidence: 99%

Morphology of Upper and Lower Bainite with 0.7 Mass Pct C

Yin

Hillert

Borgenstam

2017

Metall Mater Trans A

View full text Add to dashboard Cite

There has been an on-going discussion on the difference in formation mechanisms of upper and lower bainite. Various suggestions have been supported by reference to observed morphologies and illustrated with idealized sketches of morphologies. In order to obtain a better basis for discussions about the difference in mechanism, the morphology of bainite in an Fe-C alloy with 0.7 mass pct carbon was now studied in some detail from 823 K to 548 K (550°C to 275°C) at temperature intervals of 50 K or less. The work focused on bainite seen to start from a grain boundary in the plane of polish and showing an advancing tip in the remaining austenite. The results indicate that there is no essential difference with temperature regarding the ferritic skeleton of feathery bainite. The second stage of bainite formation, which involves the formation of both ferrite and cementite, was regarded as a eutectoid transformation and the resulting morphologies were analyzed in terms of two modes, degenerate and cooperative eutectoid transformation. There was no sharp difference between upper and lower bainite. Ways to define the difference were discussed.

show abstract

Retained Austenite and the Tempering of Martensite

Cited by 56 publications

References 0 publications

Carbide-Free Bainite: Compromise between Rate of Transformation and Properties

Carbide-Free Bainite: Compromise between Rate of Transformation and Properties

Effects of Q&P Processing Conditions on Austenite Carbon Enrichment Studied by In Situ High-Energy X-ray Diffraction Experiments

Morphology of Upper and Lower Bainite with 0.7 Mass Pct C

Contact Info

Product

Resources

About