Analysis of the impact of position in fatigue cracks on the fracture toughness of thick-walled pressure vessel material

AbstractThe testing of fracture toughness thick-walled pressure vessel material showed a vast range of different results. Pressure vessels were made by hot plastic deformation treatment. Three sets of specimens were cut-out from the vessel, each having a same orientation of fatigue cracks in relation to the vessel axis. Fracture toughness tests were performed on the SENB specimens in accordance with ASTM 1820-11. The results showed a large range of different results, even within each sets of specimens. The results of fracture toughness in the initiation zone of stable crack growth were processed by means of Weibull statistical analysis. Based on these results of a direction distribution coefficient m was obtained and results reliability interval of fracture toughness was defined