Effects of Nb/Cr on the cryogenic impact toughness of the deposited metal of ENiCrFe-9

The influence of Nb/Cr (in weight percent) on the cryogenic impact toughness of the deposited metals of ENiCrFe-9 was investigated. It was found that the round Al and Ti oxides and irregular Nb-enriched particles were dispersed in the interdendritic regions and the M23C6-type carbides were precipitated on grain boundaries. When the Nb/Cr ratio reached 0.19, an eutectic-type laves phase appeared. The volume fraction and average size of these precipitates increased significantly as the Nb/Cr ratio increased. Although the austenitic matrix exhibited ductile fracture manner, the precipitates significantly deteriorated the cryogenic impact toughness. The cryogenic impact values evidently decreased as the precipitates increased in average size and volume fraction.