Basic Study On Reconstitution Of Charpy-size Impact Specimen

The aging degree of reactor pressure vessel (RPV) can be evaluated through the ductile to brittle transition curve from the Charpy impact specimens preplaced in RPV. However the number of impact energy data is limited due to the compact structure of RPV. One of the solutions is to reconstitute new Charpy specimen from the impacted ones in order to get more impact data. However, there’s little basic research on reconstitution both in domestic and overseas although its high project application value. Against this context, basic research on charpy sized specimen reconstitution was carried out in this paper. The main research contents and conclusions are shown as follows:(1) The new location of V-notch and length of insert section used in the reconstituted specimen was studied. Based on the Cowper Symonds model and GTN model, the charpy impact at room temperature was simulated by ABAQUS. Besides, micro-hardness field of the broken specimen was used to deduce the plastic area distribution. All this suggests, the length of impacted specimen was about14mm.(2) The feasibility of reconstitution by argon arc and laser welding was explored.20mm length of elastic area from broken specimen was taken as the insert section to reconstitute new charpy specimen by argon arc and laser welding. Subsequent performance tests showed sufficient welding strength and lower temperature of the plastic zone compared with temp index290℃.(3) The temperature field of all the central test area was proved to be lower than the temp index290℃with the laser welding simulation according to the actual welding parameter.(4) Hardness and small punch test were applied to the heat treatment specimen from200℃to400℃to verify that the temperature index of290℃was prone to to be conservative.