Microstructure engineering by dispersing nano-spheroid cementite in ultrafine-grained ferrite and its implications on strength-ductility relationship in high carbon steel

Prasad, Ch. Rajendra; Bhuyan, P.; Kaithwas, C.K.; Saha, Rajib; Mandal, Sumantra

doi:10.1016/j.matdes.2017.11.019

Cited by 45 publications

(31 citation statements)

References 47 publications

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“…The unusual properties of bimodal specimen are attributed to its unique dual-phase microstructure. The fine martensite grains embedded in coarse austenite matrix of bimodal steel may be modelled as a dispersion strengthened system 32,33 . For dispersion strengthened alloys, the work-hardening rate primarily depends on the average dislocation density around particles interacting with primary dislocations 32 .…”

Section: Resultsmentioning

confidence: 99%

High Tensile Ductility and Strength in Dual-phase Bimodal Steel through Stationary Friction Stir Processing

Arora

Ayyagari

Saini

et al. 2019

Sci Rep

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The combination of high strength and good ductility are very desirable for advanced structural and functional applications. However, measures to enhance strength typically lead to ductility reduction due to their inverse correlation, nano-grained structures for an instance. Bi-modal grain structure is promising in this regard, but its realization is limited by multiple complex processing steps. Here, we demonstrate a facile single-step processing route for the development of bimodal grain structure in austenitic stainless steel, SS316L. The bimodal structure comprised of fine martensite grains (<500 nm) sandwiched between coarse austenite grains (~10 µm). The dual-phase bimodal structure demonstrated higher yield strength (~620 MPa) compared to ultra-fine grain structure (~450 MPa) concurrent with high uniform tensile ductility (~35%). These exceptional properties are attributed to unique dual-phase, bimodal grain structure which delayed the onset of plastic instability resulting in higher strength as well as larger uniform elongation and work-hardening rate. Our approach may be easily extended to a wide range of material systems to engineer superior performance.

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Section: Resultsmentioning

confidence: 99%

High Tensile Ductility and Strength in Dual-phase Bimodal Steel through Stationary Friction Stir Processing

Arora

Ayyagari

Saini

et al. 2019

Sci Rep

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“…Despite its small size, its shape and distribution in the ferrite matrix substantially affect the material's strength and formability, as has been reported by the researchers in the past. [ 12–15 ] Various models have been proposed to study the influence of cementite morphology on the global mechanical properties of the low alloyed medium carbon steels. [ 13–15 ] Due to the pinning effect of fine cementite particles present in the middle of the ferrite matrix, the ferrite grains do not grow during spheroidization annealing (Zener drag effect).…”

Section: Introductionmentioning

confidence: 99%

Investigating the Effect of Cementite Particle Size and Distribution on Local Stress and Strain Evolution in Spheroidized Medium Carbon Steels using Crystal Plasticity‐Based Numerical Simulations

Umar

Qayyum

Farooq

et al. 2020

steel research int.

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Herein, micromechanical material deformation behavior of medium carbon steel—with varying cementite particle size and distribution—under monotonic tensile load is modeled. The statistical phase morphology data are collected from the microscopy images of 83% spheroidized C45EC steel. Virtual microstructures for nine different cases are constructed using Dream.3D by varying the concentrations of small, large, and bimodal cementite particles on the ferrite grain boundaries. A crystal plasticity‐based numerical simulation model, i.e., DAMASK, is used to simulate the local material deformation behavior. The material model parameters for elastic–plastic ferrite and elastic cementite phases are adopted from the literature and calibrated by modifying the fitting parameters to match the experimentally observed material flow curve. It is observed that the cementite particle size and distribution in the primary phase affect the local mechanical behavior of the material. An analysis of deformation at 20% of global strain has helped in the qualitative understanding of factors affecting the stress and strain concentration points. The evolution of stresses and strains in the least and the most stressed representative volume elements (RVEs) has provided interesting information regarding the path followed by the dislocation movement during deformation. The study has provided insight into the factors affecting the material's global and local deformation behavior.

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“…Y phases were further shattered and some short rods changed to particles from Figure 5b. This broken and fragmented process of Y phases is like the spheroidizing process of the cementite in pearlitic steels [25,26,27]. The degree of fragmentation increases with the increase in forging deformation for Y phases and the sizes of Y phases decrease with increasing deformation.…”

Section: Resultsmentioning

confidence: 99%

Structural Properties and Phase Stability of Primary Y Phase (Ti2SC) in Ti-Stabilized Stainless Steel from Experiments and First Principles

et al. 2019

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The morphology and microstructural evaluation of Y phases in AISI 321 (a Ti-stabilized stainless steel) were characterized after hot deformation. The electronic structure and phase stability of titanium carbosulfide were further discussed by first-principle calculations. It was found that Y phases, like curved strips or bones in AISI 321 stainless steel, mostly show a clustered distribution and are approximately arranged in parallel. The width of the Y phase is much less than the length, and the composition of the Y phase is close to that of Ti2SC. Y phases have exceptional thermal stability. The morphology of Y phases changed considerably after forging. During the first calculations, the Ti2SC with hexagonal structure does not spontaneously change into TiS and TiC; however Ti4S2C2 (Z = 2) can spontaneously change into the two phases. The Ti–S bonds are compressed in Ti4S2C2 cells, which leads to poor structural stability for Ti4S2C2. There is a covalent interaction between C/S and Ti, as well as an exchange of electrons between Ti and S/C atoms. Evidently, the mechanical stability of Ti4S2C2 is weak; however, Ti2SC shows high stability. Ti2SC, as a hard brittle phase, does not easily undergo plastic deformation.

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Microstructure engineering by dispersing nano-spheroid cementite in ultrafine-grained ferrite and its implications on strength-ductility relationship in high carbon steel

Cited by 45 publications

References 47 publications

High Tensile Ductility and Strength in Dual-phase Bimodal Steel through Stationary Friction Stir Processing

High Tensile Ductility and Strength in Dual-phase Bimodal Steel through Stationary Friction Stir Processing

Investigating the Effect of Cementite Particle Size and Distribution on Local Stress and Strain Evolution in Spheroidized Medium Carbon Steels using Crystal Plasticity‐Based Numerical Simulations

Structural Properties and Phase Stability of Primary Y Phase (Ti2SC) in Ti-Stabilized Stainless Steel from Experiments and First Principles

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