Dislocation Density within Lath Martensite in Fe-C and Fe-Ni Alloys

Morito, Shigekazu; Nishikawa, Jun; Maki, Tadashi

doi:10.2355/isijinternational.43.1475

Cited by 330 publications

(179 citation statements)

References 9 publications

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“…The dislocation densities in FeN alloys are lower than those in FeC alloys with the same carbon level. 15) Furthermore, the average thickness of martensite laths in FeN alloys is also lower than that in FeC alloys as shown in Fig. 7.…”

Section: )mentioning

confidence: 97%

Effect of Solution Carbon and Nitrogen on the Microstructural Size and Crystallography of Lath Martensite in Fe–N and Fe–C Alloys

et al. 2016

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Microstructures of lath martensite that contains bcc or bct martensite crystals in FeC alloys are known to depend on the carbon content of the alloys. The effect of nitrogen content on microstructure, however, has not yet been elucidated. This study elucidates the effects of carbon and nitrogen content on microstructures via local crystallographic analysis. We found that the packet sizes are similar when the nitrogen content in the alloys are the same as the carbon content, with the packet size decreasing with increasing carbon and nitrogen content. The block and subblock thicknesses in low nitrogen lath martensite are smaller than those in low carbon lath martensite, whereas those in medium and high carbon and nitrogen lath martensites are similar. Martensite lath thickness and dislocation density in the FeN alloy laths are lower than those in the Fe C alloys laths, and the distribution of misorientation angles between adjacent the blocks and sub-blocks in FeN alloys is similar to that in FeC alloys.

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Section: )mentioning

confidence: 97%

Effect of Solution Carbon and Nitrogen on the Microstructural Size and Crystallography of Lath Martensite in Fe–N and Fe–C Alloys

et al. 2016

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“…[13,14] Dislocation densities were measured on TEM micrographs by a line intercept method with convergent beam electron diffraction analysis being used to measure the local thickness of the thin-foil specimen. [15] The mechanical properties were measured by Vickers hardness and tensile tests. The gauge dimensions of tensile test specimens were 8.5 mm in length, 2.0 mm in width, and 0.5 mm in thickness.…”

Section: Anmentioning

confidence: 99%

Ultrafine Structure and High Strength in Cold-Rolled Martensite

Huang

Morito

Hansen

et al. 2012

Metall Mater Trans A

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Structural refinement by cold rolling (10 to 80 pct reductions) of interstitial free (IF) steel containing Mn and B has been investigated from samples with different initial structures: (a) lath martensite, (b) coarse ferrite (grain size 150 lm), and (c) fine ferrite (22 lm). Unalloyed IF steel with a coarse grain size (120 lm) has also included based on a previous study. Deformation microstructures and structural parameters have been analyzed by transmission electron microscopy and electron backscatter diffraction, and mechanical properties have been characterized by hardness and tensile testing. At low to medium strains, lath martensite transforms into a cell block structure composed of cell block boundaries and cell boundaries with only a negligible change in strength. At medium to large strains, cell block structures in all samples refine with increasing strain and the hardening rate is constant (stage IV). A strong effect of the initial structure is observed on both the structural refinement and the strength increase. This effect is largest in lath martensite and smallest in unalloyed ferrite. No saturation in structural refinement and strength is observed. The discussion covers the transformation of lath martensite into a cell block structure at low to medium strains where the driving force is suggested to be a decrease in the dislocation line energy. Medium to large strain-hardening mechanisms are discussed together with structure-strength relationships assuming additive stress contributions from dislocations, boundaries, and elements in solid solution. Good agreement is found between flow stress predictions and stress values observed experimentally both in the initial undeformed martensite and in deformed samples.

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“…Attributing the carbon patterns to carbon segregation to line defects such as dislocations is not unprecedented. The dislocation density, ρ, is known to be a function of carbon content, where ρ ∼ (0.7+3.5w C ) × 10 15 m −2 [28]. The addition of nickel is reported to increase ρ slightly.…”

Section: Apt On Aged Lcmentioning

confidence: 99%

Thermodynamic aspects of carbon redistribution during ageing and tempering of Fe–Ni–C alloys

Kim

Sietsma

Santofimia

2016

Philosophical Magazine

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Carbon redistribution is known to occur during martensite ageing. The two associated processes most discussed in the literature are spinodal decomposition and carbon segregation to defects. In order to elucidate the topic, the ageing and tempering of two Fe-Ni-C alloys have been characterised by means of atom probe tomography and synchrotron radiation diffraction. Upon ageing at room temperature, carbon redistribution is clearly observed, where the process of carbon segregation to defects appears to be most likely to occur. Nevertheless, the possibility of spinodal decomposition is not entirely discarded, and the current work presents a series of discussion points that challenge our current understanding of the thermodynamic of ferrite in steels. ARTICLE HISTORY

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Dislocation Density within Lath Martensite in Fe-C and Fe-Ni Alloys

Cited by 330 publications

References 9 publications

Effect of Solution Carbon and Nitrogen on the Microstructural Size and Crystallography of Lath Martensite in Fe–N and Fe–C Alloys

Effect of Solution Carbon and Nitrogen on the Microstructural Size and Crystallography of Lath Martensite in Fe–N and Fe–C Alloys

Ultrafine Structure and High Strength in Cold-Rolled Martensite

Thermodynamic aspects of carbon redistribution during ageing and tempering of Fe–Ni–C alloys

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Dislocation Density within Lath Martensite in Fe-C and Fe-Ni Alloys

Cited by 330 publications

References 9 publications

Effect of Solution Carbon and Nitrogen on the Microstructural Size and Crystallography of Lath Martensite in Fe&ndash;N and Fe&ndash;C Alloys

Effect of Solution Carbon and Nitrogen on the Microstructural Size and Crystallography of Lath Martensite in Fe&ndash;N and Fe&ndash;C Alloys

Ultrafine Structure and High Strength in Cold-Rolled Martensite

Thermodynamic aspects of carbon redistribution during ageing and tempering of Fe–Ni–C alloys

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Product

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Effect of Solution Carbon and Nitrogen on the Microstructural Size and Crystallography of Lath Martensite in Fe–N and Fe–C Alloys

Effect of Solution Carbon and Nitrogen on the Microstructural Size and Crystallography of Lath Martensite in Fe–N and Fe–C Alloys