Case Study: Engine Exhaust Tip

Process: Metal Additive Manufacturing (AM) 

Density: 99% of Theoretical

Material: Inconel 625 Nickel-Based Superalloy

Ultimate Tensile Strength: 950 MPa minimum

Elongation: 42%

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End Use and Function

This exhaust tip is used to direct reaction gases away from combustion inside the engine of the Czinger 21 C hybrid sports car.  

Fabrication

The part was built using laser powder-bed-fusion (PBF-LB) and a built-in honeycomb structure was iteratively positioned along the flow pathway to optimize weight balance and ideal pressure drop. The exhaust tip is made from nickel-based superalloy Inconel 625 to greater than 99% theoretical density and has an ultimate tensile strength of 950 MPa, a yield strength of 655 MPa, and an elongation of 42% in the as-built condition. No post processing heat treatment is required to homogenize the microstructure. Four parts are built per day on a single AM machine using novel laser scanning strategies. The built part has a tolerance of ± 1.5 mm.

Results

Additive manufacturing enabled rapid iterative design loops, manufacturing, and testing to optimize the product design in less than one month. A similar product would take 6 months to produce via conventional manufacturing. Light weighting was a particular focus of the part design aimed at improving fuel economy.