Effect of Cooling Rate on the Microstructure of a Pressure Vessel Steel

Das, Avimanyu; S, Sunil Kumar; Kapoor, R.

doi:10.1007/s13632-019-00585-6

Cited by 15 publications

(12 citation statements)

References 51 publications

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“…The absence of low angle grain boundaries could be due to higher solidification rates. Similar conclusion has been derived by other researchers [36]. Similar effect is found in the grain size distribution (Figure 9b), while both atomization techniques produce grains of similar size, a lower solidification rate in the G.A powder appears to result in a combination of high fraction of LAGB leading to grain coarsening.…”

Section: Powder Characterizationsupporting

confidence: 90%

“…With respect to misorientation angles the C.A powder had a much higher fraction of the HAGBs This could be from the higher solidification rates and has been reported in literature [36]. At strain rates of 30,000 s -1 which is low compared to the extreme strain rates experienced in CS deposition, Guha et al [56] have shown through CPFEM that for fcc materials HAGB's result in increased thermal softening leading to zones of localized Conflicts of Interest: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.…”

Section: Discussionsupporting

confidence: 54%

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An Attempt to Understand Stainless 316 Powders for Cold-spray Deposition

Karmarkar¹,

Varadaraajan²,

Mohanty³

et al. 2023

Preprint

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Cold gas dynamic spray (CS) is a unique technique to deposit material using high strain rate solid state deformation. A major challenge for this technique is its dependence on the powder properties and lack of standards to assess them between lots and manufacturers. The motivation of this research was to understand the variability in powder atomization techniques for stainless steel powders and their subsequent properties for their corresponding impact on CS. A drastic difference (~30%) was observed in deposition efficiencies (DE) of unaltered, spherical, and similar sized stainless steel (316) powders produced using centrifugal (C.A) and traditional gas atomization (G.A) techniques. The study highlights more on differences on precursor level. Using recent advancements in large scale statistical measurements like laser diffraction shape analysis, µCT scanning, traditional methods like EBSD, nano-indentation, an attempt is made to understand the powder property. Insights on powder size and shape are documented. Significant differences were observed between C.A and G.A powders in terms of grain size, fraction of higher angle grain boundaries (HAGB) and nano hardness. The outcomes of this study would be helpful to understand the commercialization of the cold-spray process for bulk manufacturing of powder precursors

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Section: Powder Characterizationsupporting

confidence: 90%

Section: Discussionsupporting

confidence: 54%

An Attempt to Understand Stainless 316 Powders for Cold-spray Deposition

Karmarkar¹,

Varadaraajan²,

Mohanty³

et al. 2023

Preprint

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“…Previously to improve the impact toughness of bainitic RPV steel MnMoNi, Xie et al 3 have already proposed an inter-critical heat treatment procedure to introduce martensite and austenite as its constituent phases. With variations in the cooling rate, the transformation phenomena of constituent phases in 20MnMoNi55 steel were observed by Das et al 4 In addition to the above observations, a comparative study of mechanical properties with respect to variation in tempering temperature on RPV steel was also reported by several researchers. 5,6…”

Section: Introductionmentioning

confidence: 72%

Effect of microstructural constituents and morphological characteristics on low cycle fatigue behaviour of inter-critically annealed 20MnMoNi55 steel

Basu

Acharyya

Sahoo

2021

Proceedings of the Institution of Mechanical Engineers, Part L:

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The effect of varying microstructural parameters on the cyclic behaviour of dual-phase steels was studied on the basis of experimental and micromechanical finite-element simulated results. The initial bainitic morphology of as-received 20MnMoNi55 steel was transformed into ferrite and martensite through proper inter-critical heat treatment procedures. Strain-controlled low cycle fatigue tests were conducted at room temperature with different strain amplitudes at a specific strain rate of 10−3/s. The cyclic stress–strain curve, obtained through joining the peak stresses of hysteresis loops corresponding to different strain amplitude, shows an increase in strain hardening with an increase in volume fraction of martensite. Whereas the rate of cyclic softening, considering the decrease in stress amplitude with respect to elapsed cycles, increases with increasing strain amplitude. Inclusive of all affecting microstructural parameters, an original microstructure-based representative volume element associated with a crystal plasticity-based material model was adopted for conducting micromechanical finite-element simulation. In addition to several parameters associated with a crystal plasticity model, consideration of initial geometrically necessary dislocation density in constituent phases resulted in the accurate prediction of a hysteresis loop at low strain amplitude as compared with the experimental results. A variation of stress triaxiality built up in ferrite matrix with martensite fraction along with deformation inhomogeneity between ferrite and martensite was also observed through a strain partitioning phenomenon obtained from finite-element simulated results.

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“…This may be attributed to the generation of transformation strains associated with martensite formation (discussed in the following sections) within the L‐DED‐fabricated CoCrMo. [ 40 ] Hence, with increasing laser power, the reduction in cooling rate may have caused an increase in LAGB and a corresponding decrease in HAGB fraction within the as‐built CoCrMo samples (Figure 5f).…”

Section: Resultsmentioning

confidence: 99%

Thermokinetically Driven Microstructural Evolution in Laser‐Based Directed Energy‐Deposited CoCrMo Biomedical Alloy

et al. 2022

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The present work investigated additive manufacturing of CoCrMo alloy via laser‐based directed energy deposition process. A range of five different laser powers are used for the fabrication of fully dense and metallurgically sound CoCrMo samples. The solidification parameters including temperature gradient, growth rate, and the cooling rate are computationally predicted in each case, using a multitrack multilayer model. The variation in these computationally predicted solidification parameters with the different laser powers used in fabrication is linked to the evolution of microstructural features within the laser additively deposited CoCrMo samples. Evolution of ε‐hexagonally close‐packed (HCP) martensites from γ‐face‐centered cubic (FCC) phase, along with variation in thickness of these martensitic laths with respect to the varying solidification parameters associated with the laser additive deposition, is identified and investigated. The multitrack, multilayer thermokinetic model not only provides the spatial and temporal signatures of laser‐based directed energy deposited process, but uniquely considers the influence of pre‐ and postheating on microstructural evolution with their correlation with experimental observations.

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Effect of Cooling Rate on the Microstructure of a Pressure Vessel Steel

Cited by 15 publications

References 51 publications

An Attempt to Understand Stainless 316 Powders for Cold-spray Deposition

An Attempt to Understand Stainless 316 Powders for Cold-spray Deposition

Effect of microstructural constituents and morphological characteristics on low cycle fatigue behaviour of inter-critically annealed 20MnMoNi55 steel

Thermokinetically Driven Microstructural Evolution in Laser‐Based Directed Energy‐Deposited CoCrMo Biomedical Alloy

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