Fracture and Tensile Properties of Boron Added Ni-Base Superalloy at 7 and 4.2 K, and the Effect of 13 Tesla Field
Tensile and fracture properties of an aged, boron added Ni-base superalloy are investigated in liquid helium and at 7 K. The 200 hour and 923 K aging of this superalloy specimens are performed under observation of an in situ oxygen emf sensor. For tensile tests carried out under 13 tesla magnetic field a new 4 K rig is designed capable to be fitted into an existing Nb3Sn 13.5 tesla split coil. The tests carried out at 7 K are performed with a 25 kN capacity servohydraulic machine using a helium flow cryostat. To obtain the possible magnetic field effect on tensile behavior extensive tests are carried out with titanium as non magnetic reference material. Fracture tests are conducted using 4 – 6 mm diameter EDM-notched round bars at 7 K and at 4.2 K with or without magnetic field using the JETT fracture test (J evaluation on tensile test). The obtained results indicate so far that the different stiffness of the used testing systems play a significant role for the total elongation at fracture for tensile behavior as well as for JETT results. In addition, elasticplastic J-tests are performed at 4.2 K using 15 mm thick standard compact tension specimens and the obtained results are compared with current JETT test results.
KeywordsFracture Toughness Oxygen Partial Pressure Liquid Helium Total Elongation Compact Tension Specimen
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