Classification of martensite-austenite constituents according to its internal morphology in high-strength low alloy steel

Ramachandran, Dileep Chandran; Kim, Sung Dae; Moon, Joonoh; Lee, Chang‐Hoon; Chung, Jihoon; Biro, E.; Park, Yeong-Do

doi:10.1016/j.matlet.2020.128422

Cited by 35 publications

(15 citation statements)

References 15 publications

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“…On the other hand, the microstructure feature of blocky and island FCC, as shown in Figure 4 a, coinciding with the fractography shown in Figure 6 , were undetected after the EPT, suggesting this blocky and island MA feature was responsible for the lower toughness of the as-welded HAZ. This result was in agreement with some other studies [ 20 , 21 ] in which thin-film austenite was reported, but was contrary to another study [ 8 ] in which blocky austenite surrounded by martensite was found to be more effective in hindering crack propagation.…”

Section: Discussionsupporting

confidence: 91%

Eliminating the Brittleness Constituent to Enhance Toughness of the High-Strength Steel Weld Heat-Affected Zone Using Electropulsing

Chen

Xiong

et al. 2022

Materials

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The evolution of the martensite–austenite (MA) constituent in the heat-affected zone (HAZ) of high-strength steel FH690 welds when subjected to electropulsing (EP) treatment was investigated herein, with the aim of eliminating brittle MA to enhance toughness. The features induced by EPT were correlated with the microstructure and fractography through scanning electron microscopy and electron backscatter diffraction analyses, together constituting an impact property evaluation. The Charpy V-notch impact results showed EPT could improve toughness of the HAZ from 34.1 J to 51.8 J (the calibrated value was 46 J). Examinations of EP-treated microstructure showed a preferred Joule heating: at the site of the MA constituent, the cleavage fractography introduced by the MA constituent was substituted with ductile dimples with various sizes. Decreases in grain size of 40% and 47% for the matrix and the retained austenite, respectively, were achieved; while for regions without the MA constituent, microstructural modification was negligible. The temperature rise at sample surface was less than 60 °C. The mechanism behind this favorable Joule heating for the MA constituent was correlated with the electrical properties of the MA constituent in contrast with martensite matrix. The toughness enhancement of the HAZ was thus attributed to the elimination of the coarse MA constituent. The present investigation suggested that electropulsing, characterized as a narrow-duration current, is a promising method for preferred elimination of brittle factors and thus improving the toughness of HAZ of high-strength steel within a limited region with a width less than 2 mm.

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Section: Discussionsupporting

confidence: 91%

Eliminating the Brittleness Constituent to Enhance Toughness of the High-Strength Steel Weld Heat-Affected Zone Using Electropulsing

Chen

Xiong

et al. 2022

Materials

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“…The impact toughness mainly depends on the crack’s steady propagation energy. Based on Griffith’s crack propagation criterion that was developed by Orowan [ 42 ], as the grain or the second phase at the cleavage initiation could induce the micro-crack unsteady propagation, the cleavage fracture stress

and the critical event size,

, of the grain or the second phase at the crack initiation, must meet Equation (1). In other words, the critical stress,

, of local cleavage fracture is inversely proportional to the square root of the structural parameters (such as inclusions, the second phase, and grain diameter) that induce the cleavage fracture.…”

Section: Discussionmentioning

confidence: 99%

Influence of Post-Weld Heat Treatment on Microstructure and Toughness Properties of 13MnNiMoR High Strength Low Alloy Steel Weld Joint

Tian

Zhang

et al. 2021

Materials

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Weld and base metals require hot or cold working during the steel equipment manufacturing process. As a result, the components should be subjected to a normalizing heat treatment in order to recover their mechanical properties. In this study, the submerged-arc welding of the high strength low alloy (HSLA) thick steel plate(13MnNiMoR) is adapted for the vessel head under the normalizing and tempering heat treatment. The findings showed that the material toughness decreases after heating to simulate a vessel head forming process. The stamping process is carried out under the conditions of 980 °C for one hour, normalizing at 920 °C for 1 h and tempering between 600–660 °C for 2 h, respectively. The martensite-austenite (M-A) constituent is distributed in granular bainite and the boundary of austenite in island constituent. Therefore, it was deemed to be the most detrimental to Charpy-V impact toughness. Between normalizing and tempering, intercritical normalizing at 740 °C was added. As a result of the ferrite with fine particles M-A constituent, the toughness increases significantly.

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“…Although the YS and UTS of R2 are close to that of R3, its elongation is considerably lower than that of R3 probably due to the presence of massive M/A constituents in R2. Extensive studies have demonstrated that massive M/A constituents in steel are prone to trigger crack initiation due to local stress concentration between M/A and matrix and are detrimental to ductility and toughness [62][63][64][65][66][67][68]. However, M/A constituents are not always harmful and sometimes they could be favorable for mechanical properties, if they are fine in size and are homogeneously distributed [69][70][71].…”

Section: Mechanical Propertiesmentioning

confidence: 99%

“…Firstly, the M/A constituents could generate local stress concentration under applied stress due to deformation incompatibility with the matrix [71,82]. Many literature works have demonstrated that massive M/A constituents were prone to trigger crack initiation because of local stress concentration [63][64][65][66][67][68]. Meanwhile, the massive M/A constituents could result in micro-galvanic corrosion between M/A constituents and matrix due to Volta potential variation [34,87].…”

Section: Scc Mechanismmentioning

confidence: 99%

“…13 Cross-sectional morphologies of the fractures of R1 a, R2 b and R3 c, d in simulated marine atmosphere. The images in red boxes are magnified ones in white boxes [65,67,93], larger size of M/A constituents with sharp corner would cause higher local stress concentration [62,66,67,94]. Moreover, the micro-galvanic corrosion effect of larger M/A consistent could be more prominent due to their larger cathode area based on the galvanic corrosion theory [87,95].…”

Section: Scc Mechanismmentioning

confidence: 99%

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Simultaneously Improving Mechanical Properties and Stress Corrosion Cracking Resistance of High-Strength Low-Alloy Steel via Finish Rolling within Non-recrystallization Temperature

Zhao

Yang

et al. 2020

Acta Metall. Sin. (Engl. Lett.)

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The effect of hot rolling process on microstructure evolution, mechanical properties and stress corrosion cracking (SCC) resistance of high-strength low-alloy (HSLA) steels was investigated by varying the finish rolling temperature (FRT) and total rolling reduction. The results revealed granular bainite with large equiaxed grains was obtained by a total rolling reduction of 60% with the FRT of 950 °C (within recrystallization temperature T r ). The larger grain size and much less grain boundaries should account for the relatively lower strength and SCC resistance. A larger rolling reduction of 80% under the same FRT resulted in the formation of massive martensite-austenite (M/A) constituents and resultant low ductility and SCC resistance. In contrast, a good combination of strength, ductility and SCC resistance was obtained via 80% rolling reduction with the FRT of 860 °C (within non-recrystallization temperature T nr ), probably because of the fine grain size and M/A constituents, as well as a high density of grain boundary network.

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Classification of martensite-austenite constituents according to its internal morphology in high-strength low alloy steel

Cited by 35 publications

References 15 publications

Eliminating the Brittleness Constituent to Enhance Toughness of the High-Strength Steel Weld Heat-Affected Zone Using Electropulsing

Eliminating the Brittleness Constituent to Enhance Toughness of the High-Strength Steel Weld Heat-Affected Zone Using Electropulsing

Influence of Post-Weld Heat Treatment on Microstructure and Toughness Properties of 13MnNiMoR High Strength Low Alloy Steel Weld Joint

Simultaneously Improving Mechanical Properties and Stress Corrosion Cracking Resistance of High-Strength Low-Alloy Steel via Finish Rolling within Non-recrystallization Temperature

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