Visual Examination and Light Microscopy

Ganguly²,

Pardal³

2022

Preprint

In developing a wire-arc direct energy deposition process for creep resistant alloys used in high-speed flight applications, structures were built from nickel-based superalloy Rene 41. Samples of AM material were analysed for their microstructural and mechanical properties, in both as deposited (AD) and heat-treated (HT) conditions. Tensile specimens were tested at room-temperature, 538, 760, and 1000 °C. Macroscopically, large columnar grains made up of a typical dendritic structure were observed. Microscopically, significant segregation of heavier elements, grain boundary precipitates, and secondary phases were observed, with key differences observed in HT material. There was a clear distinction between failure modes at different testing temperatures and between AD and HT variants. A fractographic investigation found a progressive move from brittle to ductile fracture with increasing testing temperature in both AD and HT conditions, as well as microstructural features which support this observation.

Section: Fracture Surfacesmentioning

confidence: 84%

Section: Fractographymentioning

confidence: 85%

High Temperature Failure and Microstructural Investigation of Additive Manufactured Rene 41

Ganguly²,

Pardal³

2022

Preprint

“…The cheveron patterns seen across several specimens (seen clearly in Figure S-10, images B1 and C1), are likely to be slip steps, though striations which occur microscopically are similar in appearance. These patterns which appear on predominantly on RT, 538°C can be indicative of rapid fractures associated with more brittle behaviour [31].…”

Section: Resultsmentioning

confidence: 99%

A performance comparison of additive manufactured creep-resistant superalloys

Science and Technology of Welding and Joining

Ganguly

Pardal

2023

Creep-resistant nickel, cobalt based superalloys, selected for a high-speed flight application, deposited using Wire + Arc Additive Manufacturing (WAAM), was reported. Three different alloys, Haynes 188, Inconel 718, and Rene 41, were deposited, and tested for their hightemperature tensile properties, and the results compared with wrought data. The alloys were tested from ambient temperature to 1000°C in their as-deposited condition and after undergoing industry standard age-hardening and solutionising heat-treatments, to down select the best performing alloy under two different processing conditions. The mechanical strength of the alloys fell short of the maximum achievable in wrought condition. Precipitation-strengthened alloys, Inconel 718 and Rene 41 were found to have underperformed the most significantly, whereas solid-solution-strengthened Haynes 188 suffered the least due to WAAM.

High-temperature failure and microstructural investigation of wire-arc additive manufactured Rene 41

Int J Adv Manuf Technol

Ganguly

Pardal

2023

In developing a wire-arc plasma direct energy deposition process for creep-resistant alloys used in high-speed flight applications, structures were built from nickel-based superalloy Rene 41. Samples of additive manufacturing (AM) material were analysed for their microstructural and mechanical properties, in both as-deposited (AD) and heat-treated (HT) conditions. Tensile specimens were tested at room temperature, 538, 760, and 1000 °C. Macroscopically, large columnar grains made up of a typical dendritic structure were observed. Microscopically, significant segregation of heavier elements, grain boundary precipitates, and secondary phases were observed, with key differences observed in HT material. There was a clear distinction between failure modes at different testing temperatures and between AD and HT variants. A fractographic investigation found a progressive move from brittle to ductile fracture with increasing testing temperature in both AD and HT conditions, as well as microstructural features which support this observation.