Effect of impurity level and inclusions on the ductility and toughness of an ultra-high-strength steel

Tervo, Henri; Kaijalainen, Antti; Pikkarainen, T.; Mehtonen, Saara; Porter, David

doi:10.1016/j.msea.2017.05.013

Cited by 75 publications

(35 citation statements)

References 39 publications

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“…Previous studies on steels with similar strength levels and inclusion contents without elongated MnS inclusions have shown that there is no effect of impurity levels or inclusions on tensile properties . Therefore, the present discussion concentrates on the effect of FRT, which has been shown to have a clear effect on tensile properties .…”

Section: Discussion Of Structure – Property Relationshipsmentioning

confidence: 91%

The Influence of Microstructure on the Bendability of Direct Quenched Wear Resistant Steel

Kaijalainen

Hautamäki

Kesti

et al. 2019

steel research int.

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The influence of chemical composition and processing parameters on the microstructure and bendability of three thermomechanically rolled and directquenched wear resistant steel plates is studied. Overall, the bendability of the steels is good, but there are exceptions that are given special attention. The prior austenite condition and final microstructure is evaluated with respect to subsurface hardness and bendability. The possible effect of inclusions on bendability is taken into account. Away from the surfaces, the samples consisted mainly of auto-tempered martensite. Lowering the finishing rolling temperature (FRT) increased the total rolling reduction below the recrystallization temperature leading to pancaking of austenite and the formation of increasing fractions of polygonal ferrite (PF) and bainite near the plate surface together with an increased intensity of the shear texture component {112}<111>. Strength increased with increasing austenite pancaking provided the microstructure remained mostly martensitic. A homogeneous, largely martensitic microstructure extending across the plate thickness seemed to ensure good bendability. Microstructures that are inhomogeneous with respect to the hardness of the microconstituents, or highly ferritic, or microstructures with an intense {112}<111> shear texture component combined with elongated martensite-austenite (MA) plates in the subsurface layers resulted in the largest minimum useable bending radii.

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Section: Discussion Of Structure – Property Relationshipsmentioning

confidence: 91%

The Influence of Microstructure on the Bendability of Direct Quenched Wear Resistant Steel

Kaijalainen

Hautamäki

Kesti

et al. 2019

steel research int.

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“…Echeverria et al [12] discussed effective control of TiN-induced cleavage fracture in a bainite microstructure. Tervo et al [20] studied the effects of various inclusions on the toughness of lath martensite steel and noted that MnS and TiN inclusions have more influence on toughness than other inclusions. Liu [21] found that coarse and distributed TiN inclusions were responsible for the toughness variation.…”

Section: Introductionmentioning

confidence: 99%

The effect of TiN inclusions on the fracture mechanism of 20CrMnTi steel with lath martensite

Zhu¹,

Lu²,

Huang³

et al. 2020

Mater. Res. Express

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This study aims to investigate the effect of TiN inclusions on the fracture mechanism of 20CrMnTi steel with martensite. Size of martensite packets, blocks and TiN inclusions were characterized, and the room-temperature tensile properties, impact toughness and fracture toughness were tested of 20CrMnTi steel quenched at different temperatures. The effects of TiN inclusions on the impact toughness and fracture toughness were investigated according to the Hall-Petch relationship. The results show that, TiN inclusions are high temperature stable phases which insoluble to the matrix, mostly squared in shape and dispersed. The impact toughness and fracture toughness of 20CrMnTi steel decrease with increasing sizes of the initial austenite grains, martensite packets and blocks as the quenching temperature increases. Interestingly, the TiN inclusions strongly affect the toughness of the 20CrMnTi steel in the fracture and the fine-grained sample has a better toughness. Under high-stress concentrations, TiN inclusion particles can initiate cleavage cracking.

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“…[2][3][4] Especially in the outer surface, hardness differences in the individual phases, and the morphology as well as the initial texture, are critical for the bendability. 5,6 Hole expansion tests (HET) allow the evaluation of the stability of punched edges. There, the pre-damage of the punching has a high influence on the expandability of the hole.…”

Section: Introductionmentioning

confidence: 99%

Effect of Morphological Differences on the Cold Formability of an Isothermally Heat-Treated Advanced High-Strength Steel

Weißensteiner

Suppan

Hebesberger

et al. 2018

JOM

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Steel sheets of Fe-0.2C-2Mn-0.2Si-0.03Ti-0.003B (m%) for the automotive industry were isothermally heat-treated, comprising austenitizing and subsequent isothermal annealing at temperatures between 300°C and 500°C. As a consequence, microstructures ranging from granular bainite over lower bainite to auto-tempered and untempered martensite were obtained. In tensile, hole expansion and bending tests, the performances in different forming conditions were compared and the changes of microstructure and texture were studied by complementary electron backscatter diffraction (EBSD) analyses. Samples with granular bainitic microstructures exhibited high total elongations but lower hole expansion ratios; in subsequent EBSD and texture analyses, evidence for inhomogeneous deformation was found. In contrast, the lath-like bainitic/martensitic microstructure showed higher strength and lower elongation to fracture. This results in a reduced bendability, but also in a high tolerance against damage induced by the shearing of edges, and, thus, allows homogeneous deformation to higher strains in the hole expansion test.

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Effect of impurity level and inclusions on the ductility and toughness of an ultra-high-strength steel

Cited by 75 publications

References 39 publications

The Influence of Microstructure on the Bendability of Direct Quenched Wear Resistant Steel

The Influence of Microstructure on the Bendability of Direct Quenched Wear Resistant Steel

The effect of TiN inclusions on the fracture mechanism of 20CrMnTi steel with lath martensite

Effect of Morphological Differences on the Cold Formability of an Isothermally Heat-Treated Advanced High-Strength Steel

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