Fracture and Crack Propagation Behavior of 560 MPa Microalloyed Pipeline Steel under Different Cooling Schedules

Jin Hua Zhao; Dong Fang Li; Guo Yuan; Xue Qiang Wang; Rui Hao Li; Jian Kang; Hong Shuang Di

doi:10.4028/www.scientific.net/MSF.898.1094

Paper Titles

Application of State of the Art Assessment for Pipeline Girth Weld
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Metal Magnetic Memory Testing of Welded Joints under Fatigue Load
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Microstructure and Mechanical Properties of X80 Girth Welds with Different Welding Processes
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Mechanical Properties of Micro-Zones of X80 Pipeline Welding Joints
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Fracture and Crack Propagation Behavior of 560 MPa Microalloyed Pipeline Steel under Different Cooling Schedules
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Failure Analysis of Dissimilar Steel Weld Cracking on High and Medium Pressure Guide Pipe
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Microstructure Characterization of Inertial Friction Welding Zone for Nickel-Based Superalloy FGH96
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Welding Performance of Several New Rare Earth Tungsten Electrodes
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Abnormal Grain Growth on the Surface of Cold-Rolled AA1235 Aluminum Plate during the Annealing Process
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HomeMaterials Science ForumMaterials Science Forum Vol. 898Fracture and Crack Propagation Behavior of 560 MPa...

Fracture and Crack Propagation Behavior of 560 MPa Microalloyed Pipeline Steel under Different Cooling Schedules

Abstract:

Three kinds of pipeline steel with different microstructures were fabricated by varying cooling schedules during thermo-mechanical controlled processing (TMCP). Charpy impact property of the pipeline steels were obtained, and the fracture and crack-arrest mechanisms were further studied. The results indicated that the steels were classified into two kinds according to their microstructures, the mixture of acicular ferrite (AF), quasi-polygonal ferrite (QF), granular bainite (GB) and small fraction of degenerate pearlite (DP), and the mixed microstructure of AF and GB, respectively. The processed steel with microstructure of AF and GB exhibited more excellent low-temperature toughness and crack-arrest properties with upper shelf energy of ~281 J and energy transition temperature of ~-76°C. The mixed microstructure (AF + GB) possessing smaller effective grain size hindered the propagating of crack and consumed large amount of energy during fracture. The effective grain size of microstructure was the dominant factor controlling low-temperature toughness and crack-arrest properties of pipeline steel, which increased the high-angle boundary length per unit area and further increased the crack propagation energy during fracture.