Abstract
Microstructure and mechanical properties of CB7Cu-1 (17-4 PH) steel modified by addition of niobium, vanadium, and nitrogen were explored. Four heats of CB7Cu-1 steel: base, niobium modified to remove carbon from solution, vanadium modified, and vanadium plus nitrogen modified were melted in a 45 kg (100 lb) induction furnace under Ar atmosphere and cast into no-bake phenolic bonded sand molds and preheated ceramic shell molds. Computational thermodynamics, Scanning Electron Microscopy (SEM), X-ray diffraction, and optical microscopy techniques were used to characterize microstructures produced during homogenization, austenite conditioning, and quenching treatments. Age hardening kinetics were studied at 460°C (860°F) and 482°C (900°F). Tensile an Charpy impact properties were measured in peak-aged and over-aged conditions. Fracture surfaces were observed using SEM and complex niobium-vanadium carbonitrides were identified as fracture initiation sites. For a fixed elongation to failure, a higher tensile strength was obtained by over-aging the CB7Cu-1 steel modified with niobium, vanadium, and nitrogen; however, the Charpy impact energy was lower as compared to the peak aged base CB7Cu-1 alloy.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.