Role of retained austenite in low alloy steel at low temperature monitored by neutron diffraction

Yamashita, Takayuki; Morooka, Shigenori; Harjo, Stefanus; Kawasaki, Takuro; Koga, Norimitsu; Umezawa, Osamu

doi:10.1016/j.scriptamat.2019.10.002

Cited by 36 publications

(37 citation statements)

References 21 publications

(22 reference statements)

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“…The detailed specimen preparation procedures and TAKUMI diffractometer parameter settings used in these studies can be found elsewhere. 4,5,19,[22][23][24] Plate specimens with the parallel part of 55 mm long, 6 mm wide and 1.8 mm thick were prepared for the in situ ND experiments. The specimen was mounted horizontally in a loading machine which was installed at TAKUMI, in such a way that the ND patterns in the load-ing direction (LD) and the transverse direction (TD) were measured simultaneously using two detector banks with the scattering angles of ± 90°.…”

Section: Methodsmentioning

confidence: 99%

“…When tensile strain was applied, the α peaks became asymmetrical because of the appearances of broad α′ martensite peaks in the shoulder regions with larger lattice spacings. 4,5) Peaks attributable to the hexagonal close-packed (HCP) structure (ε) were hardly observed in the patterns of tensile-strained Steel A and Steel B. Figure 2(b) shows diffraction patterns for the LD for Steel C, as recorded under different deformation conditions.…”

Section: Fig 1 True Stress-true Strain Curves Of Steel a Steel B Amentioning

confidence: 99%

“…Transformation-induced plasticity (TRIP) steels are attracting intensive attention because they exhibit large uniform elongations and high work-hardening rates as a result of martensitic transformation during plastic loading. 1,2) Martensitic transformations in most low-alloy TRIP steels occur after macro-yielding during deformation at room temperature (RT); [3][4][5] they can therefore be categorized as straininduced transformations according to Olson and Cohen. 6) Patel and Cohen 7) observed that applied mechanical loads influence the transformation start temperature.…”

Section: Introductionmentioning

confidence: 99%

“…14) In situ neutron diffraction (ND) measurements during deformation have been confirmed as a powerful tool to understand the strengthening mechanism during deformation of multiphase steels, 15,16) including TRIP steels. 4,5,[17][18][19] In our previous study, we reported in situ ND measurements of two TRIP steels with different carbon contents, 0.2 mass% and 0.4 mass%, during tensile loading. 4) We found that martensitic transformations during deformation occurred differently for different γ -(hkl) grains.…”

Section: Introductionmentioning

confidence: 99%

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Relation between Intergranular Stress of Austenite and Martensitic Transformation in TRIP Steels Revealed by Neutron Diffraction

et al. 2021

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Section: Methodsmentioning

confidence: 99%

Section: Fig 1 True Stress-true Strain Curves Of Steel a Steel B Amentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Relation between Intergranular Stress of Austenite and Martensitic Transformation in TRIP Steels Revealed by Neutron Diffraction

et al. 2021

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“…19) Recently, we had demonstrated this high phase stress of deformation induced martensite in the TRIP steel by using in-situ neutron diffraction measurement during tensile test. 20) On the other hands, the reducing strain accumulation in a microstructure by deformation induced martensitic transformation should contribute to a high elongation in the TRIP steel, and it must be one of the improvement mechanisms of elongation by the deformation induced martensitic transformation. Figure 7 shows the volume fraction of retained austenite in each strain class (a) and the ratio of the volume fraction of retained austenite in each strain class to the total retained austenite (R class/all ) (b) as a function of nominal strain at 293 K. Here, retained austenite in each strain class was defined by comparing the ε xx strain distribution in 0.04 strain represented by four classes (Fig.…”

Section: Strain Distribution Installed By Tensile Deformation and Strmentioning

confidence: 99%

Strain Distribution and Deformation-induced Martensitic Transformation in Tension for a TRIP Steel Plate

2020

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Digital image correlation was applied to analyze the strain distribution and deformation-induced martensitic transformation of retained austenite in a low alloy transformation-induced plasticity (TRIP) steel plate under tension. The distribution of strain instilled by tensile deformation was inhomogeneous at a microscopic scale. Strain generated by deformation-induced martensitic transformation was successfully visualized and it led to a homogeneous strain distribution. The retained austenite in the high strain region transformed to martensite preferentially, which demonstrates that inhomogeneous strain distribution affects the stability of retained austenite. The high resolution strain distribution exhibited that a certain amount of strain instilled into retained austenites and there are a lot of strain concentration sites at ferrite/ austenite interfacial boundaries in high strain region. Therefore, the stress concentration at the ferrite/ retained austenite interfacial boundary occurs due to the difference of strain between the ferrite matrix and retained austenite. These strain accumulation in a retained austenite and/or stress concentration at ferrite/retained austenite interfacial boundary may induce martensitic transformation in high strain regions.

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Experimental Investigation of Lattice Deformation Behavior in S355 Steel Weldments Using Neutron Diffraction Technique

Biswal

Mehmanparast

Ganguly

et al. 2021

J. of Materi Eng and Perform

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This study aims to investigate the influence of welding process on the elastic lattice deformation and its effects on fatigue and fracture behavior of S355 G10+M steel, which is widely used in fabrication of offshore wind turbine monopile structures. In situ neutron diffraction measurements were taken on cross-weld test samples at room temperature to monitor the evolution of intergranular strains under static and cyclic loading conditions. Both static and cyclic test results have shown that the {200} orientation exhibits the least load carrying capacity while {211} had the maximum stiffness. The hkl-specific response predicted using Reuss and Kröner model were found to agree well with experimental values obtained for the heat-affected zone for all the orientations; however, discrepancies between the experimental and model predictions have been observed for the base metal and weld metal. Moreover, the microstructural differences between the weld metal and heat-affected zone resulted in the maximum elastic–plastic strain mismatch at the interface of the two regions. The results from this experiment would be useful to understand the role of crystal-specific microstrains and lattice deformation on fatigue and fracture behavior of thick-walled monopile weldments.

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Role of retained austenite in low alloy steel at low temperature monitored by neutron diffraction

Cited by 36 publications

References 21 publications

Relation between Intergranular Stress of Austenite and Martensitic Transformation in TRIP Steels Revealed by Neutron Diffraction

Relation between Intergranular Stress of Austenite and Martensitic Transformation in TRIP Steels Revealed by Neutron Diffraction

Strain Distribution and Deformation-induced Martensitic Transformation in Tension for a TRIP Steel Plate

Experimental Investigation of Lattice Deformation Behavior in S355 Steel Weldments Using Neutron Diffraction Technique

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