Modulated martensite formation behavior in Fe–Ni-based alloys; athermal and thermally activated mechanisms

Loewy, Sarah; Rheingans, Bastian; Meka, Sai Ramudu; Mittemeijer, E. J.

doi:10.1557/jmr.2015.175

Cited by 8 publications

(10 citation statements)

References 30 publications

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“…The observations of the size effect in this work are in contrast to the phenomenon observed in the majority of the literature, in which martensite sizes become smaller with increasing cooling rates [19][20][21][22][23][24]. This motivates a detailed discussion of the differences.…”

Section: Discussioncontrasting

confidence: 66%

“…The lath size is almost insensitive to changes in the prior austenite grain sizes [14,18]. Furthermore, higher cooling rates can lead to finer packet and block structures [19][20][21][22][23][24]. However, no size effect with regard to the cooling rate was found in [25].…”

Section: Introductionmentioning

confidence: 99%

“…With regard to resulting size effects on the microstructure, several discussions can be found in the literature. In [23], a modulated martensite formation in a Fe-22 wt% Ni alloy was investigated. It was concluded that subsequent simultaneous block formation is influenced by thermally activated local stress relaxation.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Size Effects Due to Different Cooling Rates of As-Quenched Martensite Microstructures in a Low-Alloy Steel

et al. 2020

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Martensite transformation is a complex mechanism in materials that is classically initiated by a suitable heat treatment. This heat treatment process can be optimized based on a better understanding of the physical mechanisms on the length scale of several prior austenite grains. It is therefore appropriate to consider individual process steps of heat treatment in isolation. The aim of this study is to characterize the microstructural size changes caused by a variation of the cooling rate applied during the quenching process. For this purpose, individual martensitic microstructures from different heat treatments are analyzed using the electron backscatter diffraction (EBSD) method. With special orientation relationships between the parent austenite and martensite, the structure of the prior austenite grains and the close packet plane packets can then be reconstructed. The influence of the heat treatments on these characteristics as well as on the martensite blocks is thus quantified. No significant influence of the quenching rate on the sizes of martensite blocks and packets could be found.

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Section: Discussioncontrasting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

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Investigation of Size Effects Due to Different Cooling Rates of As-Quenched Martensite Microstructures in a Low-Alloy Steel

et al. 2020

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“…Besides, the prior austenitic grains of EPS sample are also finer than the TS sample (Figure 3c,d). The above mentioned results indicate that the martensitic laths and prior austenitic grains of T250 steel are refined by electro-pulsing treatment, and the refined martensite is a consequence of the refined prior austenitic grains [31]. This can be attributed to the enhanced nucleation rate of austenitic transformation induced by electro-pulsing current [32].…”

Section: Microstructural Analysis and Property Measurementmentioning

confidence: 86%

Development of New Cobalt-Free Maraging Steel with Superior Mechanical Properties via Electro-Pulsing Technology

Pan

Zhao

Wang

et al. 2019

Metals

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The ductility of cobalt-free maraging steel is unsatisfactory because of the high content of Ti. Traditional heat treatment can not effectively improve the ductility of this kind steel. In this contribution, high-energy electro-pulsing is adopted in a T250 steel to solve this problem efficiently. It is found that the EPS treatment (electro-pulsing treatment under water-cooling condition) can accelerate the formation of retained austenite and nano stacking faults. Meanwhile, the microstructure is also refined by EPS treatment. Then, taking the EPS sample as the initial state, nano-reverted austenite combined with finer η-Ni3Ti precipitates are formed during EPA treatment (electro-pulsing treatment under air-cooling condition), compared with TA (traditional aging) treatment. The results of mechanical properties indicate that the strength and elongation are both enhanced by electro-pulsing treatment. Consequently, the electro-pulsing treatment can be a promising technology to devise cobalt-free maraging steel with better properties.

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“…Here we propose that a X =2 links to the formation of grouped units in auto-accommodated (shape-strain relaxing arrangements) [36][37][38][39][40] . This autocatalytic process may as well as relate to stress-assisted martensite nucleation in a plastic zone forming adjacent to a propagation event 41 .…”

Section: The Autocatalytic Pathmentioning

confidence: 98%

Autocatalysis, Entropic Aspects and the Martensite Transformation Curve in Iron-Base Alloys

Guimarães

Rios

2017

Mat. Res.

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This study advances a methodology that consolidates the description of time-dependent (isothermal) as well as time-independent (athermal) martensitic transformation curves. Our model is applied in an extended 3-space, thus permitting inclusion of the effects of autocatalysis on nucleation to be distinguished from the initiation of the transformation, as influenced by entropic barriers. Autocatalysis is then considered as a mechanism for circumventing the effect of the latter. The utility of this proposed mathematical formalism was validated with a database consisting of seven different steels that transform athermally or isothermally.

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Modulated martensite formation behavior in Fe–Ni-based alloys; athermal and thermally activated mechanisms

Abstract: Abstract

Cited by 8 publications

References 30 publications

Investigation of Size Effects Due to Different Cooling Rates of As-Quenched Martensite Microstructures in a Low-Alloy Steel

Investigation of Size Effects Due to Different Cooling Rates of As-Quenched Martensite Microstructures in a Low-Alloy Steel

Development of New Cobalt-Free Maraging Steel with Superior Mechanical Properties via Electro-Pulsing Technology

Autocatalysis, Entropic Aspects and the Martensite Transformation Curve in Iron-Base Alloys

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