MICROSTRUCTURE AND TOUGHNESS OF HAZ IN X80 PIPELINE STEEL WITH HIGH Nb CONTENT

Cheng-Liang, MU; Cheng-Jia, Chang; Hua-Min, YU; Zhang, Longfei

doi:10.3724/sp.j.1037.2009.00803

Cited by 35 publications

(25 citation statements)

References 12 publications

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“…16. Similar series of microstructures were observed in 23) and reduced effective grain size, as a result, give rise to the high strength (hardness) and enhanced ductile fracture resistance. At 3.0 kJ/mm, similar microstructure and hardness are observed that lead again to excellent toughness even at -60°C.…”

Section: Weldabilitysupporting

confidence: 63%

“…At 3.0 kJ/mm, similar microstructure and hardness are observed that lead again to excellent toughness even at -60°C. At 5.0 kJ/mm and above, however, microstructures are featured by UB+GB associated with coarse M/A constituents, that have low fraction of high angle grain boundaries and large effective grain size, [8][9][10]23) leading to decreased hardness and toughness. The present study suggests that the upper limit of heat input during welding practice for the investigated plate is 3.0 kJ/ mm, which is generally consistent with the early study.…”

Section: Weldabilitymentioning

confidence: 99%

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F460 Heavy Steel Plates for Offshore Structure and Shipbuilding Produced by Thermomechanical Control Process

Cheng

Luo

2011

ISIJ Int.

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Key parameters for controlled rolling and accelerated cooling process have been determined to industrially produce 45-50 mm heavy plates of microalloyed low carbon-equivalent SiMnCrNiCu steel for offshore structures and shipbuilding. The plates were hot rolled from continuously cast slabs with a four-high 5000 mm width mill and cooled with an accelerate-cooling system. The process was characterized by heavy finish rolling reduction ratio over 63% in austenite non-recrystallization region and interrupted accelerated cooling at 460°C to form quasipolygonal ferrite and acicular ferrite as majorities of microstructure. Yield-strength greater than 460 MPa was achieved at room temperature, and Charpy V notch impact energies of 150 to ~300 J were secured even at -80°C. Coarse granular bainite and/or degenerate upper bainite were identified harmful, causing cleavage fracture. The correlation between the fraction of highangle grain boundaries (≥15 deg) and ductile-brittle transition temperature was derived quantitatively for the advanced heavy plates. The effect of heat input during heavy plate welding on the microstructure and mechanical properties in the coarse-grained heat affect zone was discussed.

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Section: Weldabilitysupporting

confidence: 63%

Section: Weldabilitymentioning

confidence: 99%

F460 Heavy Steel Plates for Offshore Structure and Shipbuilding Produced by Thermomechanical Control Process

Cheng

Luo

2011

ISIJ Int.

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“…Recently effect of high angle boundary on impact toughness in CGHAZ has caught people's attention because of its ability to arrest crack or make it deviate during propagation [10,11]. Some researchers [7,12] have also confirmed that high density of high angle boundary is beneficial to improve CGHAZ toughness. But both the evolution of the density of high angle boundary with different thermal cycles, and the relation between high angle boundary and crystallographic feature of transformation products, have not been shown transparently and discussed in detail.…”

Section: Introductionmentioning

confidence: 95%

“…Martensite/austenite constituent (M/A) is formed during the cooling stage of the welding thermal cycles and is most commonly high carbon martensite with some retained austenite (retained austenite: the un-transformed austenite after transformation) [6]. Studies on M/A constituent [7][8][9] show that high fraction of coarsened M/A constituent could be very harmful for CGHAZ toughness. Recently effect of high angle boundary on impact toughness in CGHAZ has caught people's attention because of its ability to arrest crack or make it deviate during propagation [10,11].…”

Section: Introductionmentioning

confidence: 99%

Investigation on the microstructure and toughness of coarse grained heat affected zone in X-100 multi-phase pipeline steel with high Nb content

You

Chen

Wenjin

et al. 2012

Materials Science and Engineering: A

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107

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“…[30] Miao et al [31] found that the LB microstructure has a high density of high-angle grain boundaries ( ‡15 deg) between the bainite plates formed in identical prior austenite grain and hence reduced effective grain size, which in turn enhance the ductile fracture resistance. High heat input during welding results in the formation of coarse M/A constituents associated with GB and low misorientation grain boundaries leading to large effective grain size, deteriorating the toughness in the HAZ.…”

Section: F Microstructures and Mechanical Properties Achieved In Indmentioning

confidence: 98%

Microstructure and Mechanical Properties in Hot-Rolled Extra High-Yield-Strength Steel Plates for Offshore Structure and Shipbuilding

Qing-liang

Emi

2010

Metall Mater Trans A

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Key parameters for a thermomechanically controlled processing and accelerated cooling process (TMCP-AcC) were determined for integrated mass production to produce extra high-yieldstrength microalloyed low carbon SiMnCrNiCu steel plates for offshore structure and bulk shipbuilding. Confocal scanning microscopy was used to make in-situ observations on the austenite grain growth during reheating. A Gleeble 3800 thermomechanical simulator was employed to investigate the flow stress behavior, static recrystallization (SRX) of austenite, and decomposition behavior of the TMCP conditioned austenite during continuous cooling. The Kocks-Mecking model was employed to describe the constitutive behavior, while the JohnsonMehl-Avrami-Kolmogorov (JMAK) approach was used to predict the SRX kinetics. The effects of hot rolling schedule and AcC on microstructure and properties were investigated by test-scale rolling trials. The bridging between the laboratory observations and the process parameter determination to optimize the mass production was made by integrated industrial production trials on a set of a 5-m heavy plate mill equipped with an accelerated cooling system. Successful production of 60-and 50-mm-thick plates with yield strength in excess of 460 MPa and excellent toughness at low temperature (213 K (-60°C)) in the parent metal and the simulated coarse-grained heat affected zone (CGHAZ) provides a useful integrated database for developing advanced high-strength steel plates via TMCP-AcC.

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MICROSTRUCTURE AND TOUGHNESS OF HAZ IN X80 PIPELINE STEEL WITH HIGH Nb CONTENT

Cited by 35 publications

References 12 publications

F460 Heavy Steel Plates for Offshore Structure and Shipbuilding Produced by Thermomechanical Control Process

F460 Heavy Steel Plates for Offshore Structure and Shipbuilding Produced by Thermomechanical Control Process

Investigation on the microstructure and toughness of coarse grained heat affected zone in X-100 multi-phase pipeline steel with high Nb content

Microstructure and Mechanical Properties in Hot-Rolled Extra High-Yield-Strength Steel Plates for Offshore Structure and Shipbuilding

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