Numerical and experimental study on the effects of welding environment and input heat on properties of FSSWed TRIP steel

Mostafapour, Amir; Ebrahimpour, Ali; Saeid, T.

doi:10.1007/s00170-016-9430-6

Cited by 13 publications

(9 citation statements)

References 34 publications

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“…It was determined that HIC stopped at the boundary representing a low KAM in the 2 to 5° range, which corresponds to bainite. Therefore, the EBSD measurements and microstructural observations of the end point of the HIC propagation confirmed that bainite resisted HIC propagation [26,27].…”

Section: Resultsmentioning

confidence: 79%

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Effects of Molybdenum on HIC Susceptibility in Normalized Pressure Vessel Steels for Sour Service Applications

Park¹,

Cho²,

Park³

et al. 2019

Korean J. Met. Mater.

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This paper discusses a molybdenum-added alloy design for normalized pressure vessel steels, to reduce hydrogen induced cracking (HIC) and inhibit crack propagation. The change in microstructure produced by the modified alloy composition was analyzed to determine its effect on HIC characteristics. The microstructural change was observed by optical microscopy, hardness tests, scanning electron microscopy, and electron backscattered diffraction. The crack length ratio and crack thickness ratio were evaluated using the NACE TM 0284 standard, and ultrasonic testing was used for HIC analysis. The formation of polygonal ferrite and pearlite during the processing of the alloy creates localized areas of high stress concentration at the polygonal ferrite/pearlite interface, due to the expansion/contraction of various structures during the transformation. This results in the generation of potential hydrogen-trapping sites, subsequent HIC, and crack propagation. The addition of molybdenum leads to a decrease in the volume fraction of the pearlite structure in the steel in favor of a more beneficial bainitic ferrite microstructure, which is generated during the normalizing process. This bainitic transformation creates a more favorable expansion/contraction compatibility and reduces/breaks up the ferrite/pearlite banding. The combination of these two characteristics can result in an overall lower stress-intensity state, which can minimize hydrogen-trapping and crack propagation. This study demonstrates that the resistance of normalized pressure vessel steels to HIC can be significantly improved by incorporating molybdenum in the alloy design.

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Section: Resultsmentioning

confidence: 79%

“…It has been reported that bainite can be identified by measuring the kernel average misorientation (KAM) using EBSD. It exhibited a low KAM value, which ranged from 0.7 to 5° [ 27]. The red line in Fig.…”

Section: Resultsmentioning

confidence: 93%

Effects of Molybdenum on HIC Susceptibility in Normalized Pressure Vessel Steels for Sour Service Applications

Park¹,

Cho²,

Park³

et al. 2019

Korean J. Met. Mater.

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“…Finite element modeling was performed at rotational speed of 900, 1200, 1500 and 1800 rpm and thermal history and strain and strain rate distribution were obtained in all models. The details of the finite element model and the temperature dependent properties of the BM have been presented in the previous work of the authors of this paper [5,6].…”

Section: Methodsmentioning

confidence: 99%

“…It is reported that the thermal history and degree of deformation have significant influence on the microstructures of FSSWed TRIP steels [5,6]. Since the calculation of the thermal history and deformation during FSW/FSSW is expensive and time consuming, only a few experimental investigations were focused on thermomechanical parameters in FSW/FSSW [7][8][9], and majority of the researchers have implemented the numerical methods in this regard.…”

Section: Introductionmentioning

confidence: 99%

Finite element and experimental investigation on the effects of temperature, strain and strain rate on microstructure and mechanical properties of FSSWed TRIP steel joints

Ebrahimpour¹,

Mostafapour²,

Samadian³

2018

Mater. Res. Express

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“…9,[17][18][19] The role of RA in these multiphase microstructures is very complex and could have positive as well as adverse effects on the final engineering properties depending on the morphology, distribution, and of course the volume fraction of this microphase in the microstructures. [20][21][22] While fine bainitic ferrite and/or RA are present, besides martensite (both fresh and tempered martensite), in the case of samples isothermally held below the M s temperature, a sharply different bainite-austenite structure is achieved after isothermal holding above the M s temperature with the possibility of some FM during final cooling. This research work investigates the mechanical behaviour of a medium carbon high-silicon steel (DIN 1.5025) after the application of different holding times both above (quenching and bainitic holding (Q&B)) 23) and below (quenching and partitioning (Q&P)) the M s temperature and envisages understanding the influence of microstructural characteristics and phase constituents in establishing the structure-property correlation.…”

Section: Structure-property Correlations Of a Medium C Steel Followinmentioning

confidence: 99%

Structure-Property Correlations of a Medium C Steel Following Quenching and Isothermal Holding above and below the M<sub>s</sub> Temperature

2021

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The processing of advanced multiphase high strength steels often includes isothermal treatments around the martensite start temperature (M s) for achieving a refined microstructure comprising bainiteaustenite and/or bainite-martensite-austenite phase constituents. The objective of this research work was to investigate the structure-property relationship for a medium carbon, high-silicon DIN 1.5025 steel (Fe-0.529C-1.67 Si-0.72Mn-0.12Cr (in wt.%)) following isothermal holding close to the M s temperature (~275°C) to enable low temperature austenite decomposition. For realizing multiphase microstructures, DIN 1.5025 steel samples were austenitized at 900°C for 5 min and then quenched to the isothermal holding temperatures 350 and 250°C for various times ranging from 5 to 3 600 s. Microstructural investigation corroborated the formation of multiphase microstructure comprising tempered martensite, bainite, retained austenite, and fresh martensite in both the samples isothermally held above (350°C) and below the M s (250°C) temperature. The sample isothermally held at 250°C showed a much more refined microstructure in comparison to that held at 350°C due to the presence of a fraction of initial martensite laths which acted as potential sites for bainite nucleation. Also, the evaluation of mechanical behaviour showed that the best tensile properties in terms of high tensile strength and good ductility were achieved in samples with high volume fractions of both interlath and blocky retained austenite, particularly those isothermally treated at 350°C for 200 s and at 250°C for 600 s, respectively.

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Numerical and experimental study on the effects of welding environment and input heat on properties of FSSWed TRIP steel

Cited by 13 publications

References 34 publications

Effects of Molybdenum on HIC Susceptibility in Normalized Pressure Vessel Steels for Sour Service Applications

Effects of Molybdenum on HIC Susceptibility in Normalized Pressure Vessel Steels for Sour Service Applications

Finite element and experimental investigation on the effects of temperature, strain and strain rate on microstructure and mechanical properties of FSSWed TRIP steel joints

Structure-Property Correlations of a Medium C Steel Following Quenching and Isothermal Holding above and below the M<sub>s</sub> Temperature

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