Effects of P and S on low temperature toughness of tempered martensite in low alloy steel

抄録

It is crucial for casing steel pipes for CCS injection wells to have excellent low-temperature toughness. In this study, the effects of impurity elements P and S on the low-temperature toughness of API 5CT L80, which has a strength of 552 MPa class, were evaluated. Fracture surfaces after Charpy impact testing were subjected to fractography using machine learning to quantify the classification and fracture ratio of each fracture surface. The results revealed that the intergranular fracture surface fraction decreased with decreasing amounts of P and S.