Development, reliability evaluation and service experiences of gas turbine blade life regeneration technology

To reduce the maintenance cost by extending the replacement life of gas turbine hot parts, various methods are being developed and practically used. The life-regeneration process using hot iso-static pressing (HIP), BLE (Blade Life Extension) process™, for the 1100°C-class gas turbine buckets is one of our accomplishments and is applied for more than 16 sets since 1999. Based on those accomplishments this technology was modified and applied for the 1300°C-class gas turbine buckets. Serviced buckets operated up to the scheduled life were used to identify how the microstructures and the mechanical properties of tensile, v-notch Charpy impact, creep and low cycle fatigue properties were rejuvenated by using this technology. The microstructures and mechanical properties were confirmed to rejuvenate equivalent to or even better than the new ones. Based on the above mentioned accomplishments, the regenerated buckets were reinstalled to 1300°C-class gas turbine rotors and operated successfully since 2004.