(Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China)
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DOI:
10.7502/j.issn.1674-3962.2013.01.02
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Abstract:
Turbine blades used in heavy duty industrial gas turbines (IGT) serve at high temperatures and in an aggressive environment. The present paper gives an overview of the materials and processing techniques of IGT blades. Comparing to the turbine blades used in aero engines, IGT blades operate at high temperature, hot corrosion environment for longer time, and are with much larger size. The principles of material design and manufacture of these large blades are therefore required with special considerations. The temperature capability of materials used as IGT blade is increasing over the past decades due to the development of directionally solidified (DS) and single crystal superalloys. Features such as high Cr content and Ti/Al ratio are unique in these alloys comparing to the alloys used in aero engines. Consequently, development of alloys with high strength, high hot corrosion resistance, as well as good long term stabilities is a very challenged task. Directional solidification is one of the most important techniques in manufacturing the large blade. The development of advanced high gradient DS processliquid metal cooling process has been described. Typical microstructure and properties of superalloys processed by different DS techniques are compared. Some recent progresses in manufacturing the large blades in China have also been depicted.