Fracture behavior of stainless steel-toughened NiAl composite plate

Abstract

Analysis of the tensile and fracture behavior of a composite system consisting of boron carbide particulate-reinforced NiAl with continuous 304 stainless steel toughening regions was performed. The composite was fabricated by extrusion, with the toughening regions extending along the length of the plate in the extrusion direction. Mechanical properties were determined as a function of orientation. Tensile testing revealed that the composite modulus varied only slightly as a function of testing direction, the strength was approximately 25 pct greater in the longitudinal relative to the transverse orientation, and the transverse failure strain was only 0.3 pct compared to values in excess of 10 pct for longitudinal testing. Notched Charpy impact testing indicated that the energy absorption values varied significantly as a function of specimen location and crack growth direction, ranging from 2 to 40 Joules. In addition,K _IC values measured on subsize compact tension samples were found to range from 17 to 27 MPa ⋅ m^1/2. It was also established that theK _max values determined from the maximum load measured during compact tension testing were similar to theK _Q values calculated from instrumented notched Charpy impact testing. Finally, the fatigue crack growth characteristics of the composite were determined as a function of orientation.