The effect of hot isostatic pressing (HIP) on the fatigue life of A206-T71 aluminum castings

The effect of hot isostatic pressing (HIP) on fatigue properties of A206-T71 castings was investigated. Castings were (i) non-HIPed, or HIPed at (ii) typical HIP temperature, (iii) solution heat-treat temperature and (iv) eutectic melting temperature. HIP conditions were found to increase average and maximum fatigue life. However, the range in fatigue life also increased after HIP, which is attributed to the location of defects as well as HIP's ability to heal porosity and thin bifilms more effectively than thicker bifilms. The mechanism for healing bifilms by HIP appeared to be the fracture of bifilms and partial bonding across their surfaces. Fatigue life data were analyzed using three-parameter Weibull statistics, which showed that HIP significantly increases threshold fatigue life, but increasing HIP temperature has no effect on the threshold fatigue life.