Bulk and Sheet Thermal-Deformation Processing and Microstructure Development in Metals – Characterization, Experiments and Modeling: Session I
Sponsored by: TMS Shaping and Forming Committee
Program Organizers: Daniel Coughlin, United States Steel Corp; Kester Clarke, Los Alamos National Laboratory; Piyush Upadhyay, Pacific Northwest National Laboratory
Monday 2:00 PM
November 2, 2020
Room: Virtual Meeting Room 34
Location: MS&T Virtual
Session Chair: Daniel Coughlin, Los Alamos National Laboratory
2:00 PM
Microstructure and Mechanical Properties of Diffusion Bonded IN740H: Kaimiao Liu1; Tao Liu1; Omer N Dogan1; 1National Energy Technology Laboratory
Diffusion bonding is an important joining technique for compact heat exchangers used in supercritical CO2 (sCO2) power cycles. IN740H is one of the recently developed nickel superalloys used in extreme environment applications. There is a desire to use this alloy in compact heat exchangers to increase efficiency of sCO2 power cycles. Microstructure and mechanical properties of diffusion bonded IN740H have been studied. The detailed SEM and TEM results showed formation of (Nb, Ti)C at the bond line mainly driven by increased strain at the mating surfaces. Failure of the lap shear specimens occurred in the parent material suggesting diffusion bonding is a reliable technique to join thin IN740H sheets.
2:20 PM
Characterisation of static recrystallisation and grain growth in designed gradient microstructures: a pathway to high-throughput microstructural testing?: Nicholas Breeuwer1; Daniel Lewis2; Milo Kral1; Catherine Bishop1; 1University of Canterbury; 2Rennselaer Polytechnic Institute
High-throughput testing has been identified as a key method required to identify specific high entropy alloys for commercialisation from the enormous compositional search space. Here a method of parallel microstructural testing is demonstrated in alpha brass that shows potential for accelerating alloy testing and qualification.We use finite element analysis to design samples with controlled, inhomogeneous cold work. Subsequent interrupted annealing and optical characterisation allow the determination of recrystallisation and grain growth behaviour. We validate (i) sample design against strain from digital image correlation and (ii) grain size analysis using optical methods against EBSD methods. The results derived from gradient samples compare favourably with those obtained from homogeneous samples. The potential of this method to be used in alloy testing and qualification will be discussed.