PTSE-2: HSST pressurized thermal shock experiment with low upper-shelf energy toughness material

The second pressurized thermal shock experiment (PTSE-2) of the Heavy-Section Steel Technology Program was conceived to investigate fracture behavior of steel with low ductile-tearing resistance. In overcooling accidents, damage by fracture is potentially a problem of serious concern only in instances of vessel materials that have high transition temperatures and low Charpy impact energies at upper-shelf temperatures. In some cases the outcome of an overcooling accident analysis is principally determined by the transition temperature of the material and its influence on the initiation of brittle fracture; in such cases, low tearing resistance concomitant with low impact energy may be unimportant. If, however, crack arrest is also a contributing factor, then ductile tearing should also be considered. An arrested cleavage crack may be unstable with respect to ductile tearing. PTSE-2 is designed to produce a cleavage arrest under conditions that will immediately induce unstable tearing. The flawed material in the test vessel was fabricated to have low toughness at Charpy upper-shelf temperatures. It is the principal objective of this test to elucidate this fracture process. A secondary objective of PTSE-2 is to extend the investigation of warm prestressing that was started in the first pressurized thermal shock experiment