Fracture toughness properties of two grades of X80 supermartensitic welded pipes

摘要

Supermartensitic 13Cr stainless steels with low carbon and nitrogen content find increased applications in the oil and gas industry especially for flowlines and processing of mild sour gas. This paper focusses on the fracture toughness of tow low carbon supermartensitic stainless steel grades with 13 percent Cr produced by CLI-FAFER: X80 12Cr-4,5Ni-1,5Mo or medium alloy and X80 12Cr-6, 5Ni-2, 5Mo or high alloy, (Ref. 1). Different welded joints have been realised in 20 mm thick plates and pipes. Testing of these weldments included mechanical testing, metallographic examination and hardness measurements, impact and CTOD testing at - 40 deg C as well as realistic wide plate testing with surface notches in the weld metal and HAZ. Correlations between impact test results, CTOD and wide plate behaviour have been explored resulting in a proposal for requirements in terms of impact and/or CTOD fracture toughness.