Masao Shiga

Development of 12CR Steel Disc for Heavy Duty Gas Turbines

This paper describes research and development of 12Cr steel for heavy duty gas trubine disc. The 1300°C class gas turbine developed by Hitachi, Ltd. (H25) is commercially operated for land-based power generator (25MVA) which is realized after five years designing.The quantitative study of alloying elements, which increase mechanical properties such as creep rupture strength, tensile strength, and toughness, is discussed. The sixteen pieces of real scale disc for 1300°C class gas turbine are examined to evaluate mechanical properties in terms of real operation. The recent study of 12Cr steel disc for 1500°C class gas turbine is also discussed.© 1994 ASME

CHARACTERISTICS OF TITANIUM ALLOY 40 INCH LAST STAGE BLADE OF STEAM TURBINE

ABSTRACT Enlargement of the last stage blade (LSB) is one of the most effective ways to improve thermal efficiency. This requires development or selection of the materials which have a high tensile strength-to-weight ratio suitable for long low pressure LSBs of the steam turbine. It was confirmed that Ti-6Al-4V alloy was suited to a 40 inch last stage blade for 3600 rpm turbine instead of 12Cr materials. Shot peening was effective to improve high cycle fatigue strength. A trial 40 inch blade which was manufactured from Ti-6Al-4V alloy had offered excellent characteristics to satisfy the specified requirements.