Ferrite nucleation potency of non-metallic inclusions in medium carbon steels

Shim, Jae-Hyeok; Oh, Young Joo; Suh, Jin-Yoo; Cho, Y.W; Shim, Jae-Dong; Byun, Jung-Soo; Lee, D.N

doi:10.1016/s1359-6454(01)00134-3

Cited by 241 publications

(135 citation statements)

References 24 publications

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“…[10,49,50] Pure MnS particles are often described as inert and only MnS layers on other inclusion types are observed to promote acicular ferrite formation. In contrast, the results of the current study have shown that pure MnS particles were also active.…”

Section: Interaction Of Solute Manganese and Manganese Inclusionsmentioning

confidence: 99%

On the Capability of Nonmetallic Inclusions to Act as Nuclei for Acicular Ferrite in Different Steel Grades

Loder

Michelic

Mayerhofer

et al. 2017

Metall Mater Trans B

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Acicular ferrite nucleates intragranularly on nonmetallic inclusions, forming a microstructure with excellent fracture toughness. The formation of acicular ferrite is strongly affected by the size, content, and composition of nonmetallic inclusions, but also by the composition of the steel matrix. The potential of inclusions in medium carbon HSLA (high-strength low-alloyed) steels has been the main focus in the literature so far. The current study evaluates the acicular ferrite capability of various inclusions types in four different steel grades with carbon contents varying between 0.04 and 0.65 wt pct. The investigated steels are produced by melting experiments on a laboratory scale and subsequent heat treatment in a High-Temperature Laser Scanning Confocal Microscope. Inclusions are exclusively formed by deoxidation and desulfurization reactions. No synthetic particles are added to the melt. The inclusion landscape is analyzed by Scanning Electron Microscopy. Final ductility of the samples is evaluated based on performed tensile tests. Inclusion types in every steel grade are assessed regarding their nucleation potential always considering the interaction with the steel composition, especially focusing on the role of manganese. The effects of (Ti,Al)O x -, MnS-, and MgO-containing inclusions are discussed in detail.

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Section: Interaction Of Solute Manganese and Manganese Inclusionsmentioning

confidence: 99%

On the Capability of Nonmetallic Inclusions to Act as Nuclei for Acicular Ferrite in Different Steel Grades

Loder

Michelic

Mayerhofer

et al. 2017

Metall Mater Trans B

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“…The latter can lead to anisotropy of the steel matrix and act as a possible starting point for crack formation or corrosion [2,3]. Apart from these negative effects, in the field of 'Oxide Metallurgy' [4,5], MnS, whether as single-phase inclusion or together with titanium oxides, is known to act as a potential nucleation agent for the formation of acicular ferrite [6][7][8]. In addition, the formation of MnS prevents internal cracks resulting from the appearance of FeS and reduces hot tearing segregation [9].…”

Section: Introductionmentioning

confidence: 99%

Modeling of manganese sulfide formation during the solidification of steel

et al. 2016

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A comprehensive model was developed to simulate manganese sulfide formation during the solidification of steel. This model coupled the formation kinetics of manganese sulfide with a microsegregation model linked to thermodynamic databases. Classical nucleation theory and a diffusion-controlled growth model were applied to describe the formation process. Particle size distribution (PSD) and particle-size-grouping (PSG) methods were used to model the size evolution. An adjustable parameter was introduced to consider collisions and was calibrated using the experimental results. With the determined parameters, the influences of the sulfur content and cooling rate on manganese sulfide formation were well predicted and in line with the experimental results. Combining the calculated and experimental results, it was found that with a decreasing cooling rate, the size distribution shifted entirely to larger values and the total inclusion number clearly decreased; however, with increasing sulfur content, the inclusion size increased, while the total inclusion number remained relatively constant.

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“…[34] Since oxides inside austenite grains in the HAZ provide nucleation sites, AFs are formed around oxides, whereas other regions are mostly composed of BF or GB. [7,8] In spite of the presence of a considerable amount of oxides in the M1 steel, the volume fraction of AF is twice lower than that of the O4 steel. In order to explain this, effects of the size and no.…”

Section: Discussionmentioning

confidence: 99%

“…Most of AFs are easily formed around oxides, as oxides provide nucleation sites for AF. [8][9][10][11] Oxides cannot play a role sufficiently as crack or void initiation sites, because they are surrounded by tough AFs. [16] Thus, the reason why the fracture toughness increases with increasing no.…”

Section: Discussionmentioning

confidence: 99%

“…[5,6] Oxides act as ferrite nucleation sites at austenite grains during the welding, promote the formation of fine AF, and prevent the formation of coarse bainite or martensite. [7,8] Alloying elements such as Mg, Ti, and Al work effectively for oxide formation, and oxides formed by combining these alloying elements act as nucleation sites for fine AF during the austeniteferrite transformation. [9][10][11][12] Larger size and no.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Oxides on Tensile and Charpy Impact Properties and Fracture Toughness in Heat Affected Zones of Oxide-Containing API X80 Linepipe Steels

Sung

Sohn

Shin

et al. 2014

Metall Mater Trans A

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This study is concerned with effects of complex oxides on acicular ferrite (AF) formation, tensile and Charpy impact properties, and fracture toughness in heat affected zones (HAZs) of oxidecontaining API X80 linepipe steels. Three steels were fabricated by adding Mg and O 2 to form oxides, and various HAZ microstructures were obtained by conducting HAZ simulation tests under different heat inputs. The no. of oxides increased with increasing amount of Mg and O 2 , while the volume fraction of AF present in the steel HAZs increased with increasing the no. of oxides. The strengths of the HAZ specimens were generally higher than those of the base metals because of the formation of hard microstructures of bainitic ferrite and granular bainite. When the total Charpy absorbed energy was divided into the fracture initiation and propagation energies, the fracture initiation energy was maintained constant at about 75 J at room temperature, irrespective of volume fraction of AF. The fracture propagation energy rapidly increased from 75 to 150 J and saturated when the volume fraction of AF exceeded 30 pct. At 253 K (À20°C), the total absorbed energy increased with increasing volume fraction of AF, as the cleavage fracture was changed to the ductile fracture when the volume fraction of AF exceeded 45 pct. Thus, 45 vol pct of AF at least was needed to improve the Charpy impact energy, which could be achieved by forming a no. of oxides. The fracture toughness increased with increasing the no. of oxides because of the increased volume fraction of AF formed around oxides. The fracture toughness did not show a visible correlation with the Charpy absorbed energy at room temperature, because toughness properties obtained from these two toughness testing methods had different significations in view of fracture mechanics.

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Ferrite nucleation potency of non-metallic inclusions in medium carbon steels

Cited by 241 publications

References 24 publications

On the Capability of Nonmetallic Inclusions to Act as Nuclei for Acicular Ferrite in Different Steel Grades

On the Capability of Nonmetallic Inclusions to Act as Nuclei for Acicular Ferrite in Different Steel Grades

Modeling of manganese sulfide formation during the solidification of steel

Effects of Oxides on Tensile and Charpy Impact Properties and Fracture Toughness in Heat Affected Zones of Oxide-Containing API X80 Linepipe Steels

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