Mechanical Effects of Simulated Plasma Disruptions in Cr-Ni and Cr-Mn Stainless Steels

PLASMA DISRUPTION PHENOMENON OBSERVED IN ALL TOKAMAK FUSION REACTORS IS A MAJOR MATERIALS RELATED ISSUE. ITS EFFECTS ON THE FIRST WALL COMPONENTS HAVE TO BE CONSIDERED FOR DESIGN PURPOSE. IN FACT THESE COMPONENTS ARE SUBJECTED, IN CASE OF A DISRUPTION, TO EXTREMELY HIGH HEAT FLUXES (ABOVE 108 W/M2) ON VERY SHORT TIME SCALES (1MS). THE HIGH HEAT FLUX CAUSES VAPORIZATION AND THE PRODUCTION OF A MOLTEN LAYER. THE RESULTING DAMAGE CAN BE EVALUATED BY DETER- MINING THE PROPERTIES OF THE RESOLIDIFIED AND HEAT AFFECTED MATERIAL. IN THIS STUDY THE MORPHOLOGY, THE MICROSTRUCTURE AND THE MECHANICAL BEHAVIOUR OF SOME RESOLIDIFIED AND HEAT AFFECTED (CR-NI AND CR-MN) AUSTENITIC STAINLESS STEELS, OF INTEREST FOR NUCLEAR FUSION PURPOSE, WERE INVESTIGATED AFTER PLASMA DISRUP- TIONS, SIMULATED BY AN ELECTRON BEAM FACILITY (POWER DENSITY 8 KW/CM2, PULSE LENGTH 5-20 MS). CELLULAR CELLULAR-DENDRITIC AND DENDRITIC GROWTH MODES OCCUR- RING DURING RESOLIDIFICATION PROCESSES, SEGREGATION AND SOLIDIFICATION CRACKS WERE ANALYSED BY OPTICAL AND SCANNING ELECTRON MICROSCOPY AND MICROCHEMICAL MEASUREMENTS. THE DEGRADATION OF MECHANICAL PROPERTIES WAS EVALUATED BY HARD- NES MEASUREMENTS AND UNIAXIAL TENSILE TESTS ON SPECIMENS TAKEN FROM ZONE AFFEC- TED BY SIMULATED DISRUPTIONS. SOME FRACTURE MECHANICS PROCEDURES HAVE BEEN APPLIED IN ORDER TO EVALUATE THE IMPORTANCE OF THE RESOLIDIFICATION CRACKS

PIATTI Giovanni; 

1995-03-15

JRC5243

https://publications.jrc.ec.europa.eu/repository/handle/JRC5243,