Ductile-to-brittle Transition in a Quenched and Tempered Low Carbon High Strength Steel with Intermediate Stage Transformation Microstructures

Izumiyama, Yuta; Kayano, Rinzo; Nagai, Kotobu

doi:10.2355/tetsutohagane.100.704

Cited by 5 publications

(1 citation statement)

References 15 publications

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“…The grain distribution was dividied between the core with the coarse grains and the shell with the fine grains by the threshold of 10 μm. Average grain size is a weighted average by the area fraction [6,7]. The tensile tests were carried out on specimens with the gauge length of 3 mm and the rectangular cross section of 1 mm 2 , using a Shimadzu's Autograph AG-50kNXplus tensile testing machine at the strain rate of 5.6 × 10 -4 s -1 at room temperature.…”

Section: Methodsmentioning

confidence: 99%

A Unique Hall-Petch Relation of Harmonic Structure Designed Pure Ni

Matsuzaka,

Nagano,

Kambara

et al. 2023

MSF

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Harmonic structure has a heterogeneous microstructure consisting of bimodal grain size together with a controlled and specific topological 3D distribution of fine and coarse grains. These microstructural features of the harmonic structure materials lead to unique mechanical properties. In this study, harmonic structure was designed using the severe plastic deformation powder metallurgy process at room and cryogenic temperatures on pure nickel. There is no difference in appearance between mechanically milled (MM) powder at room and cryogenic temperatures. The compacts of the MM powder show the harmonic structure with a network fine grained area and the dispersed coarse grain area. The MM at cryogenic temperature affects the compact of the MM powder milled for 86.4 ks and its effects include an increase in shell fraction and a decrease in core grain size. Moreover, the harmonic structure materials show a synergy extra hardening in Hall-Petch relation. It is noteworthy that the harmonic structure materials exhibit a higher Hall-Petch coefficient than the homogeneous compacts despite of the same material.

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Section: Methodsmentioning

confidence: 99%

A Unique Hall-Petch Relation of Harmonic Structure Designed Pure Ni

Matsuzaka,

Nagano,

Kambara

et al. 2023

MSF

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Effect of Pearlite Volume Fraction on Two-step Ductile to Brittle Transition in Ferrite + Pearlite Structure Steel Sheets

Kawata

Umezawa

2019

ISIJ Int.

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Multi structural steels exhibit high strength and good formability; however, their performance depends on the volume fraction of the secondary phase. In our previous study, ferrite + pearlite structural steel sheet showed the characteristic two-step ductile-to-brittle transition (DBT) with decreasing temperature, and the absorbed energy curve exhibited a distinct middle shelf. In this study, we evaluated the effect of pearlite volume fraction (V P) on the DBT behavior by the Charpy impact test with sub-size specimens. For specimens without pearlite, the absorbed energy directly dropped from the upper shelf to the lower shelf with decreasing temperature. For samples with 2-3% pearlite, the absorbed energy corresponding to the transition temperature range was dispersed between the two shelves, and the transition behavior seemed to be the typical DBT behavior. When V P was increased to 21%, the absorbed energy just above the transition-finish temperature became stable at a middle level between the two shelves; thus, the existence of a distinct middle shelf was confirmed. Although the transition-start temperature increased with increasing V P , V P did not affect the transition-finish temperature and the absorbed energy at the middle shelf. These results were analyzed with a simple model based on the Yoffee diagram.

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Dominant Factor Governing Toughness in a Cr-Mo Steel for Pressure Vessel with Intermediate Stage Transformation Microstructures

2016

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The steels with intermediate stage transformation microstructures (Zw) show a good balance of strength and toughness. Especially, fracture appearance transition temperature (FATT) in Charpy impact test is one of the most important properties of steel to assure material reliability. As microstructural factors to govern FATT, the effective grain size (d EFF) on cleavage fracture surfaces is well known in ferrite-pearlitic and martensitic steels. However, the relationship between FATT and d EFF have not yet been clarified for the steels with Zw. Low-alloy heat-resistant steels for pressure vessels such as Cr-Mo steels are the type with Zw and demands for better low temperature toughness are becoming severer in recent years. The present study aims to determine the relationship between FATT and d EFF , and to clarify the microstructural factor to govern toughness in quenched and tempered Cr-Mo steel with a Zw microstructure by varying the prior austenite grain size. Not the prior austenite grain size but the bainite block section width corresponded to d EFF in the size distribution. Accordingly, FATT decreased with decreasing block section width.

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Ductile-to-brittle Transition in a Quenched and Tempered Low Carbon High Strength Steel with Intermediate Stage Transformation Microstructures

Cited by 5 publications

References 15 publications

A Unique Hall-Petch Relation of Harmonic Structure Designed Pure Ni

A Unique Hall-Petch Relation of Harmonic Structure Designed Pure Ni

Effect of Pearlite Volume Fraction on Two-step Ductile to Brittle Transition in Ferrite + Pearlite Structure Steel Sheets

Dominant Factor Governing Toughness in a Cr-Mo Steel for Pressure Vessel with Intermediate Stage Transformation Microstructures

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