Abstract
The X90 pipeline steel with high-strength and high-toughness become the most popular pipeline steel. Due to the stress triaxial constraint and fracture toughness properties are the key factors for the stable work of pipeline steel, the research on the fracture toughness of X90 is a great significance to promote the engineering application of high-strength pipeline steel. In order to investigate the stress triaxial constraint and fracture toughness properties of X90 pipeline steel, the experimental rules with different grooves size are proposed using the common toughness experiment and the corresponding numerical models are established in this paper. The resistance curves and fracture toughness of each type of specimens are obtained and compared with that of finite element analysis. Furthermore, the stress distribution, J-integral distribution and stress triaxial constraint of the specimen are analyzed, as well as the influence of side grooves size on the determination of fracture toughness is also discussed. The results obtained from the study will provide a reference to the fracture toughness evaluation research and application of X90 pipeline steel.
Highlights
With the advantages of large transportation volume, strong economy and high safety, pipeline transportation has become the main transportation mode of oil and natural gas [1].Due to the long distance and complex terrain of pipeline transportation, the high toughness, fatigue resistance, corrosion resistance and fracture resistance are the necessary properties of pipeline steel
The results showed that the fracture toughness of X80 pipeline steel decreased obviously with the decrease of temperature, and the fracture type of the specimen gradually tended to brittle fracture
In order to investigate the stress triaxial constraint and fracture toughness properties of X90 pipeline steel, the experimental rules with different side grooves are proposed using the standards experiment and the corresponding numerical models are established in this paper
Summary
Due to the long distance and complex terrain of pipeline transportation, the high toughness, fatigue resistance, corrosion resistance and fracture resistance are the necessary properties of pipeline steel. The research shows that improving the grade of pipeline steel is the most effective way to increase the oil and gas transport capacity and reduce the cost of pipeline construction and transportation [2,3,4]. The reason for this is that upgrading the grade of pipeline steel, such as X70 to X80, can reduce the amount of pipeline steel by 8% to 12%. X100 and X120 have made very slow progress in industrial application due to their high requirements for strength and toughness
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