Morphological and crystallographic features of granular and lath-like bainite in a low carbon microalloyed steel

De-Castro, David; Eres-Castellanos, Adriana; Vivas, Javier; Caballero, Francisca G.; San-Martín, David; Capdevila, Carlos

doi:10.1016/j.matchar.2021.111703

Cited by 32 publications

(10 citation statements)

References 48 publications

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“…This could be explained by the slower cooling rates in the top regions and the higher expected temperatures, which would favor the transformation into a globular bainitic or at least bainite‐like structure. [ 32 ] Further regions can also be identified that seem like a degenerated upper bainitic structure (Figure 5b). However, this structure possesses larger areas of austenitic isles compared to the bottom region of the specimen (Figure 5c).…”

Section: Resultsmentioning

confidence: 99%

Effect of Volumetric Energy Density and Part Height on the Material Properties of Low‐Alloyed Steels Manufactured by Laser‐Based Powder Bed Fusion of Metals

Bartels,

Novotny,

Albert

et al. 2023

Adv Eng Mater

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The layer‐by‐layer manufacturing approach in laser powder bed fusion of metals (PBF‐LB/M) leads to heat accumulation in the workpiece with increasing part heights. The effect of this heat accumulation on the resulting material properties has, however, only barely been studied for low‐alloyed steels. The goal of this work is to analyze the influence of different PBF‐LB/M‐specific boundary conditions like varying part heights and volumetric energy densities (VED) on the resulting material properties. It isfound that lower part regions possess similar hardness (380–410 HV1) and retained austenite values (7%–8%), independent of the applied VED. Higher energy inputs lead to higher retained austenite contents of up to 20% due to an incomplete transformation upon cooling. This rise in retained austenite content is also linked to a decreased material hardness down to 320 HV1. In higher part regions, this effect is reversed as the retained austenite content starts to decrease for the highest investigated VED. This is caused by the in situ preheating temperatures caused by heat accumulation, which favor a bainitic transformation. The part height‐specific properties indicate that the microstructure formation forms through a continuous transformation in lower part regions and through an isothermal transformation in higher regions.

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Section: Resultsmentioning

confidence: 99%

Effect of Volumetric Energy Density and Part Height on the Material Properties of Low‐Alloyed Steels Manufactured by Laser‐Based Powder Bed Fusion of Metals

Bartels,

Novotny,

Albert

et al. 2023

Adv Eng Mater

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show abstract

Section: Discussionmentioning

confidence: 99%

“…The distributions of M/A constituents are not homogeneous and their shapes are not always regular, giving rise to the vague and discontinuous lath boundaries in the optical micrographs. [46] In our opinion, for the identification of AF, the majority of adjacent laths are from different CP groups and different Bain groups could be an important criterion. Neighboring laths from different CP groups suggest that they have different lath boundary directions and thus a chaotic or interlocking morphology, and neighboring laths from different CP groups indicate that there is a high density of HAGBs, which both are key characteristics of AF.…”

Section: Identification Of Af Microstructuresmentioning

confidence: 98%

Acicular Ferrite Identification in Heat‐Affected Zone of a Ti‐Killed High Strength Low Alloy Steel

Zhao,

Gao,

Huang

et al. 2024

steel research int.

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It is frequently found in the literature that an acicular ferrite (AF) dominant microstructure has unsteady or even low‐impact toughness. It is necessary to analyze whether they are qualified for real AF. Herein, a Ti‐killed high strength low alloy steel is prepared and subjected to heat‐affected zones simulation tests to induce various AF‐like microstructures. The morphological differences of these microstructures are compared, and their crystallographic characteristics are analyzed. It is found that even within a single prior austenite grain, the transformed microstructure can be heterogeneous. Local areas having clear lath boundaries and a chaotic or interlocking morphology should be classified as AF. Adjacent laths in these areas are from different close‐packed plane and Bain groups. In contrast, local areas having vague lath boundaries and a granular‐bainite‐like morphology should be classified as granular bainite. Neighboring laths in these areas are from the same Bain group, and a relatively low density of high‐angle grain boundaries can be found. The heterogeneous microstructure consisting of granular bainite and AF has a wider grain size distribution and a higher area fraction occupied by large grains, which can lead to the scatter of Charpy impact energy. Criteria for the identification of AF are also proposed in this research.

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“…The microstructure of the simulated CGHAZ consisted of quasi-polygonal ferrite (QPF), pearlite (P), degenerated pearlite (DP), grain boundary ferrite (GBF), side-plate ferrite (FSP), Widmanstätten ferrite (WF), bainite ferrite (BF), AF, lath bainite (LB), and granular bainite (GB), which are classified and defined according to their morphologies and characteristics from the previous research. [2,[37][38][39][40][41][42][43][44][45][46][47] QPF with irregular grain boundaries was normally formed at lower temperatures at higher cooling rates. P was a mixture of layered or band-shaped ferrite and cementite.…”

Section: Microstructure Characterization and Hardness Measurementmentioning

confidence: 99%

Simulated Coarse Grain Heat‐Affected Zone Transformation Behavior of Newly Developed Zr–Ti–RE Deoxidized High‐Strength Low‐Alloy Steels with Extremely High Impact Toughness

Yin

Cheng

et al. 2023

steel research int.

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Morphological and crystallographic features of granular and lath-like bainite in a low carbon microalloyed steel

Cited by 32 publications

References 48 publications

Effect of Volumetric Energy Density and Part Height on the Material Properties of Low‐Alloyed Steels Manufactured by Laser‐Based Powder Bed Fusion of Metals

Effect of Volumetric Energy Density and Part Height on the Material Properties of Low‐Alloyed Steels Manufactured by Laser‐Based Powder Bed Fusion of Metals

Acicular Ferrite Identification in Heat‐Affected Zone of a Ti‐Killed High Strength Low Alloy Steel

Simulated Coarse Grain Heat‐Affected Zone Transformation Behavior of Newly Developed Zr–Ti–RE Deoxidized High‐Strength Low‐Alloy Steels with Extremely High Impact Toughness

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