Effect of Carbon and Nitrogen on &lt;i&gt;Md&lt;/i&gt;&lt;sub&gt;30&lt;/sub&gt;                        in Metastable Austenitic Stainless Steel

Masumura, Takuro; Fujino, Kohei; Takaki, Setsuo; Kimura, Ken

doi:10.2355/tetsutohagane.tetsu-2019-062

Cited by 10 publications

(17 citation statements)

References 23 publications

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“…A comparison between C-and N-added steels reveals that the volume fraction of DIM in C-added steels is lower than that in N-added steels, meaning that the mechanical stabilizing effect of C is higher than that of N, as reported in a previous study. [4][5][6] In these steels, ε-martensite with HCP structure is also formed as an intermediate phase of the γ→α' transformation, but we confirmed that the amount was small (5 vol.% at most) and the ε→α' transformation was completed at 70% cold rolling for all steels. 4) Figure 2 shows phase + image quality (IQ) maps (a)-(c) and crystallographic orientation maps extracted only DIM (BCC) (d)-(f) in 20% cold-rolled Base (a) (d), 0.1C (b) (e), and 0.1N steel (c) (f).…”

Section: Methodssupporting

confidence: 51%

“…In the above viewpoint, there is a difference in the effects of C and N; C is more effective in increasing the mechanical stabilization of austenite than N, [4][5][6] whereas it is generally accepted that C is more effective in increasing the hardness of athermal martensite formed by quenching than N. [7][8][9][10] Therefore, the effects of C and N on the work-hardening behavior of metastable austenitic steel are expected to be different; nevertheless, no systematic investigation has been done.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Carbon and Nitrogen on Work-hardening Behavior in Metastable Austenitic Stainless Steel

Masumura

2021

ISIJ Int.

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The effects of C and N on the work-hardening behaviors were compared in metastable austenitic steels in which varied amounts of C and N were separately added (Fe-18%Cr-8%Ni-(C,N) alloys). Although both C and N suppressed deformation-induced martensitic transformation during tensile deformation due to their austenite-stabilizing effect, they enhanced the work hardening of the steels. Comparison of C-added and N-added steels revealed that C addition more increased the work-hardening rate than N addition. In order to clarify the reason of the more significant effect of C, the individual hardness of deformed austenite and deformation-induced martensite (DIM) were measured in cold-rolled C-added and N-added steels by using a nano-indentation tester. The nanohardness of deformed austenite increased with increasing the thickness reduction and amount of added C and N. However, there is little difference between C-added and N-added steels in the hardening behavior of austenite, meaning that the difference in work-hardening rate of metastable austenitic steel between C-added and N-added steels is not derived from the hardness of deformed austenite but that of DIM. The nanohardness of DIM was significantly higher in the C-added steel than N-added steel, and thus, the main factor affecting the higher work hardening of 0.1C steel should be considered to be the higher hardness of C-containing DIM. In addition, in C-added steels, an excellent strength-ductility balance was achieved compared with N-added steel because the hard DIM is gradually formed until the later stage of deformation, meaning that pronounced TRIP effect was obtained in C-added steels than N-added steels.

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Section: Methodssupporting

confidence: 51%

Section: Introductionmentioning

confidence: 99%

Effect of Carbon and Nitrogen on Work-hardening Behavior in Metastable Austenitic Stainless Steel

Masumura

2021

ISIJ Int.

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“…Martensitic Transformation Behavior of 6Ni-0.2N-0.1C Steel Figure 5 shows the volume fraction of deformationinduced martensite at ε = 0.3 as a function of temperature in the 6Ni-0.2N-0.1C and SUS304 steels. The temperature for a volume fraction of deformation-induced martensite of 0.5 (50%) is estimated as the M d30 point 19,23) from Fig. 5.…”

Section: Effect Of Temperature On the Deformation-inducedmentioning

confidence: 99%

“…2 were a little larger than those from Calc. 3, showing that the TS of the 6Ni-0.2N-0.1C steel was influenced by the strength of α. Yoshitake et al 21) and Masumura et al 22,23) investigated the stress-strain relationship and DIMT behavior of austenitic stainless steels containing N or C. In the cases of 0.1 mass% N or C, the effect of C content on mechanical stability of austenite was a little higher than the effect of N, and the austenitic steel containing 0.1 mass% C indicated larger strength and elongation. 23) They discussed those differences from the viewpoint of deformed microstructure and their results seem to be associated with the estimated σ axial ph.…”

Section: Roles Of Deformation-induced Martensite and Austenite On Thementioning

confidence: 99%

“…Yoshitake et al investigated the effect of N and C on the work hardening behavior of austenitic stainless steels, 21) and Masumura et al made a detailed studied of the effects of the addition of N and C on the stability of austenite 22) and also proposed a modified equation that takes into account the effects of N and C on the M d30 . 23) However, there have been few quantitative studies on the role of deformation-induced martensite in the TRIP effect from the viewpoint of the strength of deformationinduced martensite.…”

Section: Introductionmentioning

confidence: 99%

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Role of Deformation-Induced Martensite in TRIP Effect of Metastable Austenitic Steels

2021

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Role of deformation-induced martensite in the transformation-induced plasticity (TRIP) of metastable austenitic steels was studied by examining effects of temperature on the tensile properties of Fe-18%Cr-6%Ni-0.2%N-0.1%C (6Ni-0.2N-0.1C) steel. The tensile properties obtained by tensile tests at various temperatures between 123 and 373 K were compared with those of SUS304 steel. The 0.2% proof stress, tensile strength, and uniform elongation of the 6Ni-0.2N-0.1C steel were larger than those of SUS304 at all temperature studied, and the mechanical stability of the austenite for the 6Ni-0.2N-0.1C steel was higher than that for the SUS304 steel. Neutron diffraction experiments at room temperature showed that the improvements in the mechanical properties in the 6Ni-0.2N-0.1C steel were associated with larger work hardening of the austenite and larger strength of the deformation-induced martensite. The increase in strength of deformation-induced martensite with N and C additions leads to better mechanical properties due to the TRIP effect, despite of smaller amounts of deformation-induced martensitic transformation.

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Modeling of the Kinetics of Strain‐Induced Martensite Transformation and the Transformation‐Induced Plasticity Effect in a Lean‐Alloyed Metastable Austenitic Stainless Steel

Mukarati

Mostert

Siyasiya

2021

steel research int.

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This article investigates the influence of temperature and strain on second‐phase transformation strengthening and the resulting mechanical properties in a lean AISI 301LN austenitic stainless steel within a temperature range of −60 to 180 °C. The volume fraction of martensite evolved is determined using nondestructive magnetic Ferritescope measurements that are adjusted by using a calibration factor of 1.7, which is established using the saturation magnetization measurements, X‐ray, and neutron diffraction measurements. The kinetics of strain‐induced martensite transformation (SIMT) as a function of strain and temperature is accurately described by a set of modified constitutive Boltzmann sigmoidal equations at temperatures below 75 °C. For this steel, the Md (30/50) temperature is determined as 61 °C. The absolute Md temperature is established as ≈109 °C, and no athermal transformation to martensite is observed upon cooling to −270 °C using cryogenic neutron diffraction facilities. Extended JMAK analysis of the transformation is used to shed light on the mechanism of martensitic transformation. It is found that the transformation‐induced plasticity (TRIP) effect due to SIMT is at a maximum at 75 °C, which is the maximum elongation temperature (MET) and calculations are performed regarding alloy development which will reduce the MET to room temperature.

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Effect of Carbon and Nitrogen on <i>Md</i><sub>30</sub> in Metastable Austenitic Stainless Steel

Cited by 10 publications

References 23 publications

Effect of Carbon and Nitrogen on Work-hardening Behavior in Metastable Austenitic Stainless Steel

Effect of Carbon and Nitrogen on Work-hardening Behavior in Metastable Austenitic Stainless Steel

Role of Deformation-Induced Martensite in TRIP Effect of Metastable Austenitic Steels

Modeling of the Kinetics of Strain‐Induced Martensite Transformation and the Transformation‐Induced Plasticity Effect in a Lean‐Alloyed Metastable Austenitic Stainless Steel

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