An In-Situ Scanning Electron Microscopy Study of the Bonding between MnS Inclusions and the Matrix during Tensile Deformation of Hot-Rolled Steels

Hosseini, Seyed; Temmel, Cornelius; Karlsson, Birger; Ingesten, Nils-Gunnar

doi:10.1007/s11661-007-9122-9

Cited by 56 publications

(53 citation statements)

References 7 publications

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“…In steel, the situation is even more severe, since bonding between the MnS and the steel matrix is weak, if it exists at all. [25] That implies that the material contains rather large intrinsic flaws, which are especially detrimental in the short transverse direction.…”

Section: Steel Cleanness and Inclusion Populationmentioning

confidence: 99%

“…It can be assumed that the flattened MnSÕs debond immediately after the first loading cycles from the steel matrix in the short transverse E specimens. [25,42] Those more or less inherent flaws each start a fatigue crack; the cracks eventually interlink and form a large defect in the material. This interlinking can occur when two single fatigue cracks grow together; this, then, leaves a parting line between the single sulfides in the fracture surface ( Figure 12) or, if the cracks are offset because the initiating sulfides are offset, also due to shear (Figures 11 and 14).…”

Section: B Fatigue Crack Initiationmentioning

confidence: 99%

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Fatigue Isotropy in Cross-Rolled, Hardened Isotropic-Quality Steel

Temmel

Karlsson

Ingesten

2008

Metall Mater Trans A

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Deformation and forging operations often introduce microstructural orientation and, therewith, mechanical anisotropy to steel. Flattened manganese sulfide inclusions are held responsible for a great part of fatigue anisotropy. Isotropic-quality (IQ) steel maintains the mechanical isotropy of the material, even after a deformation operation. Isotropic material generally contains little S and, therewith, few manganese sulfides. Further, the IQ steels used in this investigation were Ca treated. The Ca treatment improves the shape stability of the sulfides, even during a hotworking deformation. Two commercial materials were compared for their fatigue response, a standard medium-carbon steel with 0.04 wt pct S and a low-sulfur variant that underwent IQ treatment. The two batches were cross-rolled to plates with a deformation ratio of 4.5, leading to in-plane isotropy. Tension-compression fatigue testing was performed in longitudinal and short transversal directions relative to the rolling plane. The results showed strong anisotropy of the fatigue behavior for the standard material. The performance in the short transverse direction, with the principal stress perpendicular to the flattened inclusions, was inferior. The IQ material with nearly spherical inclusions was almost perfectly isotropic, with only slightly worse fatigue response in the short transverse direction.

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Section: Steel Cleanness and Inclusion Populationmentioning

confidence: 99%

Section: B Fatigue Crack Initiationmentioning

confidence: 99%

Fatigue Isotropy in Cross-Rolled, Hardened Isotropic-Quality Steel

Temmel

Karlsson

Ingesten

2008

Metall Mater Trans A

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“…To further reduce costs, the free-cutting element S is usually added to form MnS inclusions for the purpose of improving machinability [1][2][3]. Since the machinability and mechanical properties of steels are significantly affected by the morphology and distribution of MnS inclusions, numerous studies have focused on the formation mechanism and shape control of MnS for years [4][5][6][7][8][9][10][11]. According to the classic work by Sims and Dahle [8], MnS can be broadly classified by morphology into three types: (1) globular MnS (Type I); (2) fine rod-like MnS (Type II); and (3) angular MnS (Type III).…”

Section: Introductionmentioning

confidence: 99%

Effects of cooling rate and Al on MnS formation in medium-carbon non-quenched and tempered steels

Wang

et al. 2015

Int J Miner Metall Mater

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Abstract:The effect of Al on the morphology of MnS in medium-carbon non-quenched and tempered steel was investigated at three different cooling rates of 0.24, 0.43, and 200°C⋅s. The formation mechanisms of three types of MnS were elucidated based on phase diagram information combined with crystal growth models. The morphology of MnS is governed by the precipitation mode and the growth conditions. A monotectic reaction and subsequent fast solidification lead to globular Type I MnS. Type II MnS inclusions with different morphological characteristics form as a result of a eutectic reaction followed by the growth in the Fe matrix. Type III MnS presents a divorced eutectic morphology. At the cooling rate of 0.24°C·s , the formation of Type I and Type II MnS inclusions is promoted, and the influence of Al is negligible. The results of this work are expected to be employed in practice to improve the mechanical properties of non-quenched and tempered steels.

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“…In most forged materials, manganese sulfides lead to anisotropic behavior, with considerably lowered fatigue strength in the least favorable directions. [17][18][19] To overcome these limitations, the manganese sulfides would need both to have an equiaxed shape and to be well distributed in the material. …”

Section: F Glide Bands and Crack Patterns On Specimen Surfacesmentioning

confidence: 99%

Modified Railway Wheel Steels: Production and Evaluation of Mechanical Properties with Emphasis on Low-Cycle Fatigue Behavior

Ahlström

Karlsson

2009

Metall Mater Trans A

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Railway wheels are exposed to high mechanical and thermal loads. The objective of this study has been to develop wheels that are more resistant to damage from these loads. Fourteen different materials have been produced in the form of full-scale railway wheels. Parameters that have been varied include the chemical composition, production processes, and heat treatment. The materials have been investigated microstructurally and by hardness, tensile, and impact toughness testing. In addition, the low-cycle fatigue (LCF) behavior has been characterized at room temperature and at subzero temperatures. The results indicate improvement in microstructure and mechanical properties for some materials and it is probable that these materials would endure better in service.

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An In-Situ Scanning Electron Microscopy Study of the Bonding between MnS Inclusions and the Matrix during Tensile Deformation of Hot-Rolled Steels

Cited by 56 publications

References 7 publications

Fatigue Isotropy in Cross-Rolled, Hardened Isotropic-Quality Steel

Fatigue Isotropy in Cross-Rolled, Hardened Isotropic-Quality Steel

Effects of cooling rate and Al on MnS formation in medium-carbon non-quenched and tempered steels

Modified Railway Wheel Steels: Production and Evaluation of Mechanical Properties with Emphasis on Low-Cycle Fatigue Behavior

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