The Turbine Blade - A Case Study in Creep-limited Design

The turbine blade - a case study in creep-limited design 

In the last chapter we saw how a basic knowledge of the mechanisms of creep was an important aid to the development of materials with good creep properties. An impressive example is in the development of materials for the high-pressure stage of a modern aircraft gas turbine. Here we examine the properties such materials must have, the way in which the present generation of materials has evolved, and the likely direction of their future development. 

As you may know, the ideal thermodynamic efficiency of a heat engine is given by 

Let us first examine the development of turbine-blade materials to meet the challenge of increasing engine temperatures. Although so far we have been stressing the need for excellent creep properties, a turbine-blade alloy must satisfy other criteria too. They are listed in Table 20.1. 

The first - creep - is our interest here. The second - resistance to oxidation - is the subject of Chapter 21. Toughness and fatigue resistance (Chapters 13 and 15) are obviously important blades must be tough enough to withstand the impact of birds 

---