Effect of simulated welding thermal cycle on microstructure and mechanical properties of X90 pipeline steel

Zhao, Wei‐Guang; Wang, Wei; Chen, Shaohui; Qu, Jinbo

doi:10.1016/j.msea.2011.06.046

Cited by 49 publications

(12 citation statements)

References 16 publications

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“…During the cooling process, to ensure the stability of austenite, the carbon atoms constantly diffuse into untransformed austenite, leading to a carbon-rich zone formed, and this concentration does not reach the extent of carbide precipitation. The part of the carbonrich austenite transforms into martensite, the other part is retained austenite, and the M-A constituent is formed [17,18]. M-A constituent becomes a potential crack source, which causes stress concentration, and an embrittlement appears [19,20].…”

Section: Resultsmentioning

confidence: 99%

Microstructure evolution and properties of reheated coarse grain heat-affected zone of 900 MPa grade HSLA steel

Qin¹,

Qiao²,

Wu³

et al. 2020

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The welding thermal simulation technology was used to simulate secondary thermal cycle of coarse grain heat-affected zone (CGHAZ) of BWELDY960Q steel, and the change of microstructure and toughness in CGHAZ after reheating was studied in detail. The results show that when the peak temperature of the secondary thermal cycle is 1200 and 1000 • C, the microstructure of reheated coarse grain heat-affected zone (RCGHAZ) is martensite; when the peak temperature is 800 • C, the microstructure of RCGHAZ constitutes of martensite, granular bainite and M-A constituent. The toughness of CGHAZ is improved undergoing secondary thermal cycle, but it is still lower than that of base metal. Compared with the mechanical properties of CGHAZ, the hardness values of inter-critical and sub-critical RCGHAZ are decreased, while the toughness of super-critical and sub-critical RCGHAZ is increased. Impact fracture exhibits evident plastic deformation, the edge of fracture has tearing edges and corners, and microscopic morphology presents the characteristics of dimp fracture. K e y w o r d s : HSLA steel, reheated coarse grain heat-affected zone, microstructure, properties

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Section: Resultsmentioning

confidence: 99%

Microstructure evolution and properties of reheated coarse grain heat-affected zone of 900 MPa grade HSLA steel

Qin¹,

Qiao²,

Wu³

et al. 2020

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“…Although the PAG sizes and microstructures in HAZ are changed with increasing heat input from 100–400 kJ cm −1 during the welding thermal cycle simulation process, LBZ, which is comprising coarse GBFs, ferrite side plate (FSP) and upper bainite (Bu), has not been formed within the HAZs of all three steel samples. In addition, the HAZ microstructures in M100 and M200 mainly compose of bainite lathes are beneficial to obtain excellent toughness . In addition, the well‐developed IAF in the HAZ microstructure of M400 brings the excellent HAZ toughness.…”

Section: Discussionmentioning

confidence: 99%

Effect of Welding Heat Input on Microstructure and Toughness of Heated‐Affected Zone in Steel Plate with Mg Deoxidation

Yang

Wang³

et al. 2017

steel research int.

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Effect of heat input on the microstructure and toughness of heat-affected zone (HAZ) in steel plate with Mg deoxidation has been investigated through welding thermal cycle simulation method. With the heat input increasing from 100-400 kJ cm À1 , the average prior-austenite grain (PAG) size is increased from 43 to 56 and then to 173 mm, and the HAZ microstructure is changed from fine bainite lath to relative larger bainite lath and then to grain boundary ferrite (GBF) and intragranular acicular ferrite (IAF). With the heat input increasing up to 400 kJ cm À1 , a great amount of IAF is nucleated by the MgO-MnS inclusions with the size about 2 mm. The Charpy impact values at À40 8C of HAZ are larger than 140 J, and excellent low temperature HAZ toughness is obtained for the 68 mm thickness steel plate with Mg deoxidation with the heat input in the range from 100-400 kJ cm À1 .

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“…With the further application of pipeline steels for long distance transportation and in harsh environments, the combination of excellent toughness and weldability becomes more and more important, in addition to high strength [2]. However, the balance of high strength and good toughness in steels can be disturbed by the thermal cycles experienced during welding, resulting in the poor toughness of local areas [3].…”

Section: Introductionmentioning

confidence: 99%

The Role of the Bainitic Packet in Control of Impact Toughness in a Simulated CGHAZ of X90 Pipeline Steel

Guo

Fan

Wang

et al. 2016

Metals

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X90 pipeline steel was processed with the simulated coarse grain heat affect zone (CGHAZ) thermal cycle with heat input varying from 30 kJ/cm to 60 kJ/cm, the microstructures were investigated by means of optical microscope (OM), scanning electron microscope (SEM), electron backscattering diffraction (EBSD), and transmission electron microscope (TEM), and the impact properties were evaluated from the welding thermal cycle treated samples. The results indicate that the microstructure is primarily composed of lath bainite. When decreasing the heat input, both bainite packet and block are significantly refined, and the toughness has an increased tendency due to the grain refinement. The fracture surfaces all present cleavage fracture for the samples with different heat inputs. Moreover, the average cleavage facet size for the CGHAZ is nearly equal to the average bainite packet size, and the bainitic packet boundary can strongly impede the crack propagation, indicating that the bainitic packet is the most effective unit in control of impact toughness in the simulated CGHAZ of X90 pipeline steel.

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Effect of simulated welding thermal cycle on microstructure and mechanical properties of X90 pipeline steel

Cited by 49 publications

References 16 publications

Microstructure evolution and properties of reheated coarse grain heat-affected zone of 900 MPa grade HSLA steel

Microstructure evolution and properties of reheated coarse grain heat-affected zone of 900 MPa grade HSLA steel

Effect of Welding Heat Input on Microstructure and Toughness of Heated‐Affected Zone in Steel Plate with Mg Deoxidation

The Role of the Bainitic Packet in Control of Impact Toughness in a Simulated CGHAZ of X90 Pipeline Steel

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