New insights from crystallography into the effect of refining prior austenite grain size on transformation phenomenon and consequent mechanical properties of ultra-high strength low alloy steel

Wu, Bobo; Wang, Xiaolei; Wang, Z.Q.; Zhao, Jingxiao; Jin, Yuansheng; Wang, C.S.; Chen, Shang; Misra, R.D.K.

doi:10.1016/j.msea.2018.12.057

Cited by 73 publications

(19 citation statements)

References 28 publications

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“…Coarse carbides are however noted within the martensite between the ferrite crystals and they are significantly coarser compared to the N H Q H condition. Many authors [3][4][5]19] have investigated the effect of martensite misorientation mechanical properties, and it has been shown that misorientations >45° are representat of the internal misorientation of the martensite. This misorientation is considered of s nificant utility to improve mechanical properties.…”

Section: Resultsmentioning

confidence: 99%

“…Two factors that contribute to toughness are high angle grain boundaries (HAGB) and retained austenite [1,2]. While HAGB have been reported to be of utility in arresting crack growth, the effect of retained austenite is convoluted [3][4][5]. In new third generation advanced high strength sheet steels, retained austenite is considered necessary to obtain the elevated ductility and work hardening rates measured through quasi-static tensile testing.…”

Section: Introductionmentioning

confidence: 99%

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Heat Treatment and Austenitization Temperature Effect on Microstructure and Impact Toughness of an Ultra-High Strength Steel

Field

Cluff

Limmer

et al. 2021

Metals

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Heat treatment parameters were varied to determine the effect of normalizing and austenitizing temperature on the properties of an ultra-high strength wrought steel. Normalizing temperature did not have a significant effect on strength and ductility. Higher normalizing temperatures led to an increase in final prior austenite grain size and a slight loss in toughness. Austenitizing temperature of 825 °C was insufficient to produce a fully austenitic structure prior to quenching and led to sub-par impact behavior. The best properties were obtained after austenitizing at 915 °C followed by water quenching; the resulting quasi static properties were shown to be a yield strength of 1380 MPa with an ultimate tensile strength of 1670 MPa and 12.5% total ductility. Charpy V-notch impact properties as high as 52 J at −40 °C and 75 J at 25 °C and the behavior were achieved using higher austenitizing temperatures as well.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Heat Treatment and Austenitization Temperature Effect on Microstructure and Impact Toughness of an Ultra-High Strength Steel

Field

Cluff

Limmer

et al. 2021

Metals

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“…Therefore, the intervariant boundary was concentrated in the same Bain group and CP group. The variant selection of the same Bain group causes the formation of low angle grain boundaries; thus it does not improve the grain refinement of martensitic microstructures 12,19,38,39 . Studies 19,39 have reported that the driving force of austenite transformation is a determining factor for the modification of variant selection from the same Bain group to different Bain groups or CP groups, which also cause martensitic/bainite grain refinement.…”

Section: Resultsmentioning

confidence: 99%

“…The variant selection of the same Bain group causes the formation of low angle grain boundaries; thus it does not improve the grain refinement of martensitic microstructures 12,19,38,39 . Studies 19,39 have reported that the driving force of austenite transformation is a determining factor for the modification of variant selection from the same Bain group to different Bain groups or CP groups, which also cause martensitic/bainite grain refinement. Wu et al 39 observed that the variant group in a single grain changes from the same Bain group to different Bain groups as the average prior austenite grain size decreases from 15 μm up to 6.4 μm.…”

Section: Resultsmentioning

confidence: 99%

Microstructure and Pitting Corrosion Resistance of Quenched, Single Tempered and Double Tempered AISI 420 Martensitic Stainless Steel

et al. 2021

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The crystallographic aspects after air-quenching treatment and the pitting corrosion resistance after single tempering and double tempering treatments of AISI 420 martensitic stainless steel were studied using optical microscopy, Electron Backscatter Diffraction and potentiodynamic polarization tests. The results showed that the observed average orientation relationship (OR) was closer to the Greninger-Troiano (G-T) OR model with a minimum average deviation of 2.66°. The average OR of AISI 420 steel with respect to austenite matrix was φ1 = 3.6°, Φ = 46.0°, φ2 = 6.2° in the area mapped. Blocks showed variant pairs belonging to the same Bain group forming sub-blocks with misorientation 5.51° < 6 0 11> (V1/V4 pair), consequently, the AISI 420 martensitic stainless steel showed higher intervariant boundary density for the same Bain group and close-packed plane group. In the same air-quenching condition, the different sizes of prior austenite grain in the microstructure did not influence the variant selection. The air-quenching and single tempering treatments did not impair the pitting corrosion resistance and did not cause significant loss of hardness in relation to the air-quenched treatment. Therefore, the double tempering should be dispensed saving production costs.

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“…Thus, the low-temperature toughness is decreased. In recent years, the toughness of high-strength low alloy steel can be improved by refining the prior austenite grain, because the fine prior austenite increases the density of PAGBs and high angle grain boundaries [46,47]. In fact, the refinement of prior austenite results in a finer packet/block size of the microstructure.…”

Section: The Effect Of Prior Austenite On Low-temperature Impact Tougmentioning

confidence: 99%

Microstructure and Charpy Impact Toughness of a 2.25Cr-1Mo-0.25V Steel Weld Metal

Yan

Cao

et al. 2020

Materials

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The demand for heat-resistant steel has increased owing to its utility in numerous devices that must withstand high steam pressures and high temperatures, such as turbine rotors and blades in ultra-supercritical power plants. It is inevitable to join heat-resistance steel part by welding method, so it is important to maintain the toughness of the weld metals. In this study, the microstructure, low-temperature impact toughness, and fracture surface of as-welded and post-weld heat treatment (PWHT) of 2.25Cr-1Mo-0.25V weld metal were investigated. The microstructures of the as-welded and PWHT specimens are granular bainite and ferrite, respectively. This work revealed the relationship between effective microstructure nearby crack initiation origin and low temperature impact toughness for both the as-welded and PWHT specimens. The evolution of the microstructure and prior austenite was then investigated using confocal laser scanning microscopy (CLSM) to observe the formation of coarse ferrite grain structures. A suggestion for enhancing the low-temperature toughness was provided based on the effect of adjusting Mn content and forming acicular ferrite.

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New insights from crystallography into the effect of refining prior austenite grain size on transformation phenomenon and consequent mechanical properties of ultra-high strength low alloy steel

Cited by 73 publications

References 28 publications

Heat Treatment and Austenitization Temperature Effect on Microstructure and Impact Toughness of an Ultra-High Strength Steel

Heat Treatment and Austenitization Temperature Effect on Microstructure and Impact Toughness of an Ultra-High Strength Steel

Microstructure and Pitting Corrosion Resistance of Quenched, Single Tempered and Double Tempered AISI 420 Martensitic Stainless Steel

Microstructure and Charpy Impact Toughness of a 2.25Cr-1Mo-0.25V Steel Weld Metal

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