Experimental investigation of Fracture Toughnees for Superalloy LDZ-125

This paper describes a new high temperature moire interferometric method that uses the lithephotographic technique to etch a high density cross zero-thickness grating on the surface of a thin LDZ-125 nickel base alloy,single edge notch(SEN) specimen.The specimer was put in the furnace with quartz window to transmit the optical information.Otherwise,a U-V set was arranged in the optical path in order to gain both the fringe pattern graphs of vertical and horizontal displacenent fields simultaneously.The experimental scanned and digitized data were provided for the automatical numerical computation of the J-integral and associatecd HRR field within the confines of a constitutive relation and the final output was the fracture criterion J_1c.