Synergistic action of hydrogen gas and weld defects on fracture toughness of X80 pipeline steel. (March 2019)

• Record Type: Journal Article
• Authors: An, Teng; Zhang, Shuai; Feng, Min; Luo, Bingwei; Zheng, Shuqi; Chen, Liqiang; Zhang, Lin
• Is Part Of: International journal of fatigue. Volume 120(2019)
• Page Start: 23
• Page End: 32
• Publication Date: 2019-03
• Subjects: X80 weld metal -- Hydrogen gas -- Fracture toughness -- Weld defects; Materials -- Fatigue -- Periodicals; Materials -- Fatigue; Periodicals; 620.1122
• DOI: 10.1016/j.ijfatigue.2018.10.021
• Languages: English
• ISSNs: 0142-1123

Abstract

Highlights: Measured FCG rates and fracture toughness of X80 steel welds in H2 environment. The synergistic action of weld defects and hydrogen was discussed. Defects governed the decrease in fracture toughness. Hydrogen increased the reduction of fracture toughness caused by defects. Abstract: This study investigates the influence of hydrogen gas on the fatigue crack growth and fracture toughness of X80 welded metal. Tests are conducted in nitrogen and hydrogen environments. The results indicate that hydrogen increased the fatigue crack growth rate by an order of magnitude and reduced the Jm ( 12.7 ) (fracture toughness) of the base metal and weld metal. Jm ( 12.7 ) of the welded specimens decreased by 38.55% because of the hydrogen. The decrease in Jm ( 12.7 ) of the specimens with welding defects depended on the type of defects. The inside welding cracks began to grow because of hydrogen and stress. The fracture mode was brittle fracture which result in a 51.63% reduction in Jm ( 12.7 ) . The inclusion Mn3 TiSi governed the reduction in Jm ( 12.7 ) for specimens with inclusions, and hydrogen increased this reduction by 76.52%. Therefore, defects were the dominant factor for the decrease in fracture toughness, and hydrogen facilitated the failure of the material.