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Multi-Scale FEA Modeling of Brazed Joint Structures in Ni-based Superalloys for Gas Turbine Applications

Brazed joints are commonly used for manufacture and repair of aerospace components including high temperature turbine components. However, when designing and modeling brazed joints it is important to be able to account for the size and distribution of phases and microconstituents, for their properties, and for property gradients across the joint. Therefore, Rolls Royce is interested in the development of a multi-scale finite element analysis (FEA) model for prediction of microstructure and mechanical properties in brazed joints and braze repaired structures of Ni-based superalloy castings.

This is a broad scope that will be accomplished in multiple phases that may include effects of braze process parameters on microstructural evolution, estimation of mechanical properties, fracture toughness and fatigue life, and fitness-for-service assessment. Research objectives for the first phase are to characterize and model property gradients in braze lap joints of CMSX-4 alloy, vacuum furnace brazed with AMS 4777 and Amdry 775 filler metals. Phase transformation analysis was determined with a novel SSDTA technique for braze alloys. Metallurgical characterization and thermodynamic simulations are used to develop FEA models of both micro-scale and macro-scale features of the braze joints. Corresponding micro-scale and macro-scale mechanical testing will be performed to validate/adjust these models.  The data and modeling methodology generated during this research will enable Rolls Royce to begin developing a database for brazed joint properties; and to model and design simple brazed joints

Sponsor:  Rolls Royce Corporation
Research Scientists: Dr. Boian Alexandrov and Dr. Avraham Benatar
Graduate Student: Bryan Riggs
Collaborator: Dr. Ray Xu, Rolls Royce