Effect of high-temperature water and hydrogen on the fracture behavior of a low-alloy reactor pressure vessel steel

摘要

Structural integrity of reactor pressure vessels (RPV) is critical for safety and lifetime. Possible degradation of fracture resistance of RPV steel due to exposure to coolant and hydrogen is a concern. In this study tensile and elastic-plastic fracture mechanics (EPFM) tests in air (hydrogen pre-charged) and EFPM tests in hydrogenated/oxygenated high-temperature water (HTW) was done, using a low-alloy RPV steel. 2-5 wppm hydrogen caused embrittlement in air tensile tests at room temperature (25 degrees C) and at 288 degrees C, effects being more significant at 25 degrees C and in simulated weld coarse grain heat affected zone material. Embrittlement at 288 degrees C is strain rate dependent and is due to localized plastic deformation. Hydrogen pre-charging/HTWexposure did not deteriorate the fracture resistance at 288 degrees C in base metal, for investigated loading rate range. Clear change in fracture morphology and deformation structures was observed, similar to that after air tests with hydrogen. (C) 2016 Elsevier B.V. All rights reserved.