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Recrystallization Reduction for Directionally Solidified / Single Crystal Superalloys by Shot Peening at the Same Flow Stress of γ and γ' Phase

IP.com Disclosure Number: IPCOM000198274D
Published in the IP.com Journal: Volume 10 Issue 8B (2010-08-23)
Included in the Prior Art Database: 2010-Aug-23
Document File: 1 page(s) / 90K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

The mechanical properties of Directionally Solidified (DS) and Single Crystal (SC) superalloys have been significantly improved due to elimination of the transverse grain boundaries perpendicular to the applied stress. Advanced DS and SC superalloys are widely used for gas turbine applications due to their superior thermal, fatigue and creep properties. Although these superalloys have desirable mechanical strengths to very high temperatures, they tend to be susceptible to environmental influence on the surface, and especially, recrystallization layers may be formed during manufacturing process, high temperature application or rejuvenation/repair process. When the recrystallization layer is formed, the interface of the layer and matrix is sensitive to external loading because of incompatibility of deformation. Therefore, it has detrimental effects on the mechanical properties such as LCF, HCF or creep (LCF: Low-Cycle Fatigue; HCF: High Cycle Fatigue).

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Recrystallization Reduction for Directionally Solidified / Single Crystal low Stress of γ and γ' Phase

Superalloys by Shot Peening at the Same F

Idea: Guofeng Chen, Ph.D, CN-Beijing; Lei Cao, Ph.D, CN-Beijing

The mechanical properties of Directionally Solidified (DS) and Single Crystal (SC) been significantly improved due to elimination of the transverse grain boundaries p applied stress. Advanced DS and SC superalloys are widely used for gas turbine a their superior thermal, fatigue and creep properties.

Although these superalloys have desirable mechanical strengths to very high tempe
to be susceptible to environmental influence on the surface, and especially, recrystallizatio may b
process. When the recrystallization layer is formed, the interface of the layer and m external loading because of incompatibility of deformation. Therefore, it has detri mechanical properties such as LCF, HCF or creep (LCF: Low-Cycle Fatigue; HCF Fatigue).

The prevention of recrystall
hard to control. γ and γ' are the main equilibrium phases in the cast superalloys most of the volume. It has been found that the dissolution of γ' phase is the main rea to the rapid growth of recrystallization grain. The driving force for the disso
density of stacking defaults and dislocations in the γ' phase generated during plastic room temperatures.

So, it is useful to treat the γ/γ' phase superalloy at high temperatures t
density of γ' phase in order to reduce the stored energy in the γ' phase. This leads t dissolution of γ' phase during the subsequent solution treatment. However, with incr temperature, it is difficult to treat and also impractical for the actual application. Mo increased treating temperatures also lead to stress decreasing for b...