熱間等方加圧処理（HIP）によるNi基鋳造合金の疲労強度改善

抄録

Hot isostatic pressing (HIP) has generally considered to improve fatigue strengths of cast materials. To study the effect of HIP on the fatigue strength of Ni-based cast alloy IN100, a fatigue test was carried out on both as-cast and HIP specimens at 650 and 850°C. The test results showed that HIP increased the fatigue strength by 20 ~ 30％ at both temperatures and reduced the data scatter. For the as-cast specimens, the fatigue cracks always initiated from the inside of specimens and their fracture origins were casting defects. For the HIP specimens, however, some fatigue cracks initiated from the surface and others initiated from the inside. In most cases, their fracture origins were not casting defects but carbides of Ti and Mo. It was found that when HIP was conducted and the casting defects became small enough, the fatigue strength was dominated by the carbide size.