Effects of microstructural variation on Charpy impact properties in heavy-section Mn-Mo-Ni low alloy steel for reactor pressure vessel

Hong, Sung-Mo; Song, Ju Sun; Kim, Min‐Chul; Choi, Kwon-Jae; Lee, Bong-Sang

doi:10.1007/s12540-016-5568-x

Cited by 17 publications

(3 citation statements)

References 31 publications

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“…Banding in steel leads to anisotropic mechanical properties. This is especially true for impact toughness properties which can be sensitive to orientation and depth of specimen sampling [7,8]. Banding is caused by segregations larger than the dendrite scale (microsegregations), but smaller than channels (macrosegregation) [9].…”

Section: Introductionmentioning

confidence: 99%

Characterisation of mesosegregations in large steel ingots

Gutman

Kennedy

Roch

et al. 2023

IOP Conf. Ser.: Mater. Sci. Eng.

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The chemical composition mapping of low-alloyed steel ingots used for the nuclear industry is crucial in the manufacturing of forgings and their final quality mastering. Mechanical properties of forged and hot-rolled steels may be affected by chemically segregated bands. These bands arise from segregations that appear at the scale of a few grains in the as-cast structure: the so-called mesosegregations. While segregation at the scale of dendrite arms (microsegregation) and the scale of the casting (macrosegregation) is well understood and can be readily characterized, only little is known about the formation of mesosegregation. The first step towards understanding the cause behind mesosegregation formation can be brought through comprehensive chemical characterisation at the scale of several grains (mesoscopic scale), which requires using different characterisation techniques compared to micro- or macrosegregation characterisation. We developed a sampling and characterisation methodology that allows segregations to be mapped at the mesoscopic scale using micro X-ray fluorescence (μXRF). Characterisation technique, sampling methodology, and sample size must be adapted to consider the different solidification structures; both at smaller (dendrite arms, grains) and larger (macrostructure) scales. Segregations were characterised on a 113 x 98 mm2 steel plate extracted from a low-alloyed steel large ingot.

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Section: Introductionmentioning

confidence: 99%

Characterisation of mesosegregations in large steel ingots

Gutman

Kennedy

Roch

et al. 2023

IOP Conf. Ser.: Mater. Sci. Eng.

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“…Low-alloy steels are used for nuclear pressure vessels, steam generators, and other applications in nuclear power plants where conventional steels do not meet the required endurance strength. From this perspective, they are essential materials for ensuring higher safety and durability of nuclear power plants and contribute to increasing power generation efficiency [ 6 , 7 , 8 ]. However, low-alloy steels are also used as special structural parts in the aerospace and automotive industries and in the production of gears and crankshafts, where high requirements are imposed for high tensile strength, temperature resistance, corrosion resistance, fatigue resistance, and fracture toughness [ 9 , 10 , 11 , 12 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

Rheological Characteristics of Fe–C–Cr(Ni) Alloys

et al. 2023

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The principal objective of this project was to investigate the rheological properties of Fe–C–Cr and Fe–C–Ni-based low-alloy steels using an Anton Paar high-temperature rotational viscometer up to 1550 °C. The emphasis was placed on determining the liquidus temperatures and evaluating the flow and viscosity curves and the temperature dependence of dynamic viscosity. All were studied depending on the change in the content of chromium (0.010–4.863 wt%), nickel (0.001–4.495 wt%), and carbon (0.043–1.563 wt%). It was shown that the dynamic viscosity decreases with increasing nickel content and increases with increasing carbon and chromium content. The experimental data of the flow curves were fitted using the Herschel–Bulkley model with a good agreement between the measured and calculated values. Characterization of the internal structure was performed by SEM and EDX analyses, confirming non-significant changes in the microstructure of the original and remelted samples. The phase composition of the selected samples was also determined using JMatPro 12.0 simulation software (Sente Software Ltd., Guildford, UK).

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“…During forging and hot IOP Publishing doi:10.1088/1757-899X/1281/1/012061 2 rolling certain segregation patterns are transformed (in shape and size) to banded patterns which can lead to anisotropic mechanical properties. In banded patterns, impact toughness is highly anisotropic: the measured toughness depends on the direction of sampling and its depth in the forged piece [7,8]. Hardness of the steel is linked to it carbon content; hence the hardness varies in banded segregations patterns, leading to hardness anisotropy in forged parts [9].…”

Section: Introductionmentioning

confidence: 99%

Modelling of spatial distribution of segregations in large steel ingots by analysis of centimetric segregation maps

Gutman,

Kennedy,

Boukellal

et al. 2023

IOP Conf. Ser.: Mater. Sci. Eng.

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Mesosegregation appears during the solidification of low-alloyed steels at the scale of a few grains. It causes chemically segregated bands in forgings manufactured from steel ingots. As this may affect the mechanical properties of the produced parts, it is crucial to understand the formation of such segregation patterns. While both microsegregation and macrosegregation are well understood and can be readily characterized, little is known about the formation of mesosegregation. In this paper we present a data analysis method to identify the characteristic scales and patterns of mesosegregation. Segregation was mapped on centimetric samples, using micro X-Ray fluorescence (µXRF). The fine sampling grid used reveals segregation patterns at different scales. To identify and distinguish the mesoscale segregation patterns from smaller and larger present patterns, a numerical data analysis technique based on spatial filtering was used. It can identify characteristic scales of mesosegregation patterns on 2D serial cut samples, leading to 3D reconstruction. This approach combined with simulation studies, will ultimately pave the way to a comprehensive understanding of the formation of mesosegregation.

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Effects of microstructural variation on Charpy impact properties in heavy-section Mn-Mo-Ni low alloy steel for reactor pressure vessel

Cited by 17 publications

References 31 publications

Characterisation of mesosegregations in large steel ingots

Characterisation of mesosegregations in large steel ingots

Rheological Characteristics of Fe–C–Cr(Ni) Alloys

Modelling of spatial distribution of segregations in large steel ingots by analysis of centimetric segregation maps

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