Study of MA Effect on Yield Strength and Ductility of X80 Linepipe Steels Weld

Huda, Nazmul; Lazor, Robert; Gerlich, A.P.

doi:10.1007/s11661-017-4171-1

Cited by 17 publications

(8 citation statements)

References 30 publications

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“…In addition, Davis and King [2] suggest that there will be debonding of MA from matrix due to a difference in hardness between MA and the matrix during tensile tests, along with debonding of MA in elevated temperature tensile testing at 196°C. Huda et al [50] showed the debonding of MA in room temperature tensile test. Figure 12 shows that the hardness difference between the MA and ferrite matrix is reduced after tempering.…”

Section: Tensile Testingmentioning

confidence: 99%

Temper-treatment development to decompose detrimental martensite–austenite and its effect on linepipe welds

Huda

Ding

Gerlich

2017

Materials Science and Technology

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A tempering cycle was developed via heat treatment to study the decomposition of detrimental martensite–austenite (MA). The heat treatment cycle was found to preferentially decompose hard MA with a critical size of ≥1 µm, which decreases the hardness of these microconstituents after tempering at 300°C for 10 min. The dislocation density inside the MA and in the surrounding matrix was also decreased. Tempering of the X80 weldments containing MA reveals a similar decomposition behaviour. During transverse weld tensile testing of welds, a fracture occurred in the heat-affected zone due to void formation at the MA/ferrite interfaces. However, a fracture occurred in base metal with improved strength and ductility after tempering, in comparison to the fracture in the heat-affected zone of as-welded samples.

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Section: Tensile Testingmentioning

confidence: 99%

Temper-treatment development to decompose detrimental martensite–austenite and its effect on linepipe welds

Huda

Ding

Gerlich

2017

Materials Science and Technology

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“…When the amount of retained austenite stabilized at room temperature was recorded maximum at about 15.3 (±1) vol.% in the Q&B samples held for a moderate time of 200 s at 350 • C salt bath ( Figures 5 and 6, Table 3), more carbon atoms have been rejected from bainite into the adjacent prior austenite areas. As a result, a fraction of films and pools of retained austenite which were located between bainitic crystals were stabilized down to room temperature on the subsequent water quenching, resulting in the retention of a high fraction of carbon-enriched stable austenite in the micro-composite microstructures with mostly thin film-like or blocky morphologies [61].…”

Section: Fe-sem Micrographsmentioning

confidence: 99%

Detection and Estimation of Retained Austenite in a High Strength Si-Bearing Bainite-Martensite-Retained Austenite Micro-Composite Steel after Quenching and Bainitic Holding (Q&B)

Pashangeh

Zarchi

Banadkouki

et al. 2019

Metals

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To develop an advanced high strength steel with reasonable ductility based on low alloying concept as well as micro-composite microstructure essentially consisting of bainite, martensite and retained austenite, a Si-bearing, low alloy medium carbon sheet steel (DIN1.5025 grade) was subjected to typical quenching and bainitic holding (Q&B) type isothermal treatment in the bainitic region close to martensite start temperature (Ms) for different durations in the range 5s to 1h. While the low temperature bainite has the potential to provide the required high strength, a small fraction of finely divided austenite stabilized between the bainitic laths is expected to provide the desired elongation and improved work hardening. Various materials characterization techniques including conventional light metallography, field emission scanning electron microscopy FE-SEM, electron backscatter diffraction (EBSD), differential thermal analysis, X-ray diffraction (XRD) and vibrating sample magnetometry (VSM), were used to detect and estimate the volume fraction, size and morphology and distribution of retained austenite in the micro-composite samples. The results showed that the color light metallography technique using LePera’s etching reagent could clearly reveal the retained austenite in the microstructures of the samples isothermally held for shorter than 30s, beyond which an unambiguous distinction between the retained austenite and martensite was imprecise. On the contrary, the electron microscopy using a FE-SEM was not capable of identifying clearly the retained austenite from bainite and martensite. However, the EBSD images could successfully distinguish between bainite, martensite and retained austenite microphases with good contrast. Although the volume fractions of retained austenite measured by EBSD are in accord with those obtained by XRD and color light metallography, the XRD measurements showed somewhat higher fractions owing to its ability to acquisition and analyze the diffracted X-rays from very finely divided retained austenite, too. The differential thermal analysis and vibrating sample magnetometry techniques also confirmed the stabilization of retained austenite finely divided in bainite/martensite micro-composite microstructures. In addition, the peak temperatures and intensities corresponding to the decomposition of retained austenite were correlated with the related volume fractions and carbon contents measured by the XRD analysis.

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“…Larger prior austenite grains and coarse M/A components in the coarse grain zone of pipeline steels lead to poor low-temperature toughness. [6,22,23] The toughness of high strength low alloys (HSLA) steel is negatively impacted by the presence of rough upper bainite structure and M/A components, as suggested by Lambert Perlade et al [18] According to Davis et al [24] the formation process of the M/A components will generate significant internal stress, which will eventually lead to the formation of microcracks. Di et al [25] have suggested that the chain like M/A components distributed at grain boundaries can lead to a significant decrease in toughness.…”

Section: Introductionmentioning

confidence: 99%

Effect of Microstructure on Mechanical Properties of X65MS Welded Pipe Joint

Zhang,

Wei,

Wang

et al. 2024

steel research int.

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The mechanical properties of welded joints have a crucial impact on the safety of pipelines. This article focuses on examining the correlation between the microstructure and mechanical properties of welded joints of X65MS pipeline steel for sour service. The results indicate that the welding thermal cycle forms the microstructure consisting of acicular ferrite, granular bainite, and polygonal ferrite. The hardness across the joint ranges from 210 and 270 HV, peaking within the welded zone and decreasing towards the base metal (BM). At −40 °C, the welded zone shows the lowest impact energy of 53 J, while heat‐affected zones exhibit superior impact toughness exceeding 270 J with the highest impact energy of 326 J. This can be attributed to the exceptionally fine‐grained microstructure, a small quantity of small‐sized martensite‐austenite (M/A) constituents in the heat affected zone. As for the low toughness of the weld, the main factors can be attributed to the presence of large‐sized elongated M/A constituents and inclusions.

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Study of MA Effect on Yield Strength and Ductility of X80 Linepipe Steels Weld

Cited by 17 publications

References 30 publications

Temper-treatment development to decompose detrimental martensite–austenite and its effect on linepipe welds

Temper-treatment development to decompose detrimental martensite–austenite and its effect on linepipe welds

Detection and Estimation of Retained Austenite in a High Strength Si-Bearing Bainite-Martensite-Retained Austenite Micro-Composite Steel after Quenching and Bainitic Holding (Q&B)

Effect of Microstructure on Mechanical Properties of X65MS Welded Pipe Joint

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