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CharEffect of normalising on grain refinement of large low pressure rotors: Numerical and experimental studies
J. F. Gu, L. Z. Han,R. K. Chen
Abstarct: Experimental investigations, numerical simulation and physical simulation were undertaken to study the effect of normalising on grain refinement of large low pressure (LP) rotors. Specimens were pretreated to obtain coarse grained structures after forging then normalised. The results indicated that lower normalising temperature produces a more pronounced grain refining effect. Grain size evolution in the centre of the LP rotor during normalising in production was predicted using a method combining numerical simulation with laboratory scale physical simulation. The grain size was found to decrease with increasing number of normalising cycle, with the grains at the centre of the LP rotor coarsening most during processing. A four-cycle normalising process is proposed that can refine the grain size of a 2·8 m diameter rotor forging to finer than ASTM 5·9.
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