The effect of austenite prestrain above the Md temperature on the martensitic transformation in Fe-Ni-Cr-C alloys

Strife, J. R.; Carr, M. J.; Ansell, G. S.

doi:10.1007/bf02642861

Cited by 66 publications

(28 citation statements)

References 6 publications

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“…This also indicates that lenticular martensite interacts more weakly with the deformation structure in γ than lath martensite, as supposed previously. 18) Since the habit plane of V17 is the closest to the compression plane among selected V1, V6, V16 and V17, as shown in Fig. 5(b), the highest fraction of V17, shown in Fig.…”

Section: Discussionmentioning

confidence: 89%

Comparison of Variant Selection between Lenticular and Lath Martensite Transformed from Deformed Austenite

Chiba

Miyamoto

2013

ISIJ Int.

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A variant selection of ausformed lath martensite in an Fe-9Mn alloy (MS = 602 K) and ausformed lenticular martensite in an Fe-25Ni-0.5C alloy (MS = 220 K) are compared quantitatively using EBSD measurements combined with a method for the reconstruction of austenite orientation. Differences were found in the selected variants by ausforming between those two martensite morphologies. In ausformed lath martensite, variants with habit planes parallel to the active slip planes in austenite were preferentially selected. This variant selection in lath martensite may be attributed to the preferential nucleation on the microband structures in austenite and lack of growth inhibition from the microband boundaries. On the other hand, in ausformed lenticular martensite, variants with habit planes parallel to the compression plane were preferentially selected. The reason for this is that lenticular martensite whose habit plane is parallel to the compression plane can grow easily in austenite grains elongated along the compression plane. This means fewer disturbances for those variants to grow with a habit plane parallel to the compression plane than for other variants.

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Section: Discussionmentioning

confidence: 89%

Comparison of Variant Selection between Lenticular and Lath Martensite Transformed from Deformed Austenite

Chiba

Miyamoto

2013

ISIJ Int.

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“…It is interesting, however, that the decrease in content was from 27.9 ± 0.4 vol% to 17.3 ± 0.3 vol%, meaning that the majority of the austenite remains stable under conditions where there is intense deformation at the surface. This is undoubtedly a consequence of a phenomenon known as mechanical stabilisation [34,35], where the plastic deformation of austenite prevents martensitic transformation because the latter requires the existence of a glissile interface. It is likely that the effect is exaggerated by the fact that the austenite is present in a finely divided state -a reduction in the grain size of austenite reduces its martensite-start temperature [36,37].…”

Section: X-ray Diffractionmentioning

confidence: 99%

Dry rolling/sliding wear of nanostructured bainite

Bakshi

Leiro

Prakash

et al. 2014

Wear

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The abrasive wear of carbide-free bainitic steel under dry rolling/sliding conditions has been studied. It is demonstrated that this nanostructure, generated by isothermal transformation at 200• C, has a resistance to wear that supersedes that of other carbide-free bainitic steels transformed at higher temperatures. The experimental results, in combination with a theoretical analysis of rolling/sliding indicates that under the conditions studied, the role of sliding is minimal, so that the maximum shear stresses during contact are generated below the contact surface. Thus, the hardness following testing is found to reach a maximum below the contact surface. The fine scale and associated strength of the structure combats wear during the running-in period, but the volume fraction, stability and morphology of retained austenite plays a significant role during wear, by work-hardening the surface through phase transformation into very hard martensite.

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“…This difference in stabilization mechanism is also directly apparent from Figure 5, and based on these observations and considerations, it is argued that the linear decrease of T KM with increasing fraction of bainite shown in Figure 8 (x c C constant) is best explained by mechanical stabilization of the austenite. [22,23] The displacive growth of bainite is accompanied with a shape change of the grains, which leads to a plastic deformation of the surrounding austenite. The increased strength of the austenite means that a higher driving force is needed to initiate the transformation to martensite, and therefore the start temperature T KM for the remaining austenite is decreased.…”

Section: A Mechanical Stabilization Of Austenite Due To a Displacivementioning

confidence: 99%

“…[21] However, the dislocations induced in the austenite due to prior transformation can also retard the subsequent transformation to martensite, which is known as mechanical stabilization. [22,23,25] The dislocation debris interferes with the movement of the glissile interface that constitutes the growth. When the strain buildup in the remaining austenite accompanying the transformation exceeds a critical value, the further transformation at a certain temperature below M s is suppressed.…”

Section: A Mechanical Stabilization Of Austenite Due To a Displacivementioning

confidence: 99%

Martensite Formation in Partially and Fully Austenitic Plain Carbon Steels

Bohemen

Sietsma

2009

Metall Mater Trans A

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The progress of martensite formation in plain carbon steels Fe-0.46C, Fe-0.66C, and Fe-0.80C has been investigated by dilatometry. It is demonstrated that carbon enrichment of the remaining austenite due to intercritical annealing of Fe-0.46C and Fe-0.66C does not only depress the start temperature for martensite, but also slows the progress of the transformation with temperature compared to full austenitization. In contrast, such a change of kinetics is not observed when the remaining austenite of lean-Si steel Fe-0.80C is stabilized due to a partial transformation to bainite, which suggests that the stabilization is not of a chemical but of a mechanical nature. The growth of bainite and martensite is accompanied by a shape change at the microstructural scale, which leads to plastic deformation and thus strengthening of the surrounding austenite. Based on this stabilizing mechanism, the athermal transformation kinetics is rationalized by balancing the increase in driving force corresponding to a temperature decrease with the increase in strain energy required for the formation of martensite in the strengthened remaining austenite.

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The effect of austenite prestrain above the Md temperature on the martensitic transformation in Fe-Ni-Cr-C alloys

Cited by 66 publications

References 6 publications

Comparison of Variant Selection between Lenticular and Lath Martensite Transformed from Deformed Austenite

Comparison of Variant Selection between Lenticular and Lath Martensite Transformed from Deformed Austenite

Dry rolling/sliding wear of nanostructured bainite

Martensite Formation in Partially and Fully Austenitic Plain Carbon Steels

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