Handbook of Case Histories in Failure Analysis
An Environmentally Assisted Cracking Evaluation of UNS C64200 (Al–Si–Bronze) and UNS C63200 (Ni–Al–Bronze)
An air system on a marine platform unexpectedly shut down due to the failure of a union nut, which led to an investigation to quantify the material limitations of bronze alloys in corrosive marine environments. The study focused on two alloys: Al-Si bronze, as used in the failed component, and Ni-Al bronze, which has a history of success in naval applications. Material samples were examined using chemical analysis, SEM imaging, and corrosion testing. Investigators also analyzed precracked tension specimens, exposing them to different conditions to quantify stress intensity thresholds for environmentally assisted cracking. Al-Si bronze was found to be susceptible to subcritical intergranular cracking in air and seawater, whereas Ni-Al bronze was unaffected. Both materials, however, are susceptible to cracking in the presence of ammonia, although the subcritical crack growth rate is two to three times higher in Ni-Al bronze. Based on the results of this work, the likelihood of subcritical cracking under various conditions can be reasonably estimated, which, in the case at hand, proved to be quite high.
Michelle Koul, Jennifer Gaies, An Environmentally Assisted Cracking Evaluation of UNS C64200 (Al–Si–Bronze) and UNS C63200 (Ni–Al–Bronze), Handbook of Case Histories in Failure Analysis, Vol 3, Edited By Larry Berardinis, ASM International, 2019, p 266–276, https://doi.org/10.31399/asm.fach.v03.c9001789
Download citation file:
The ASM Data Ecosystem is a new and innovative product line that arms ASM Members and the scientific community with the tools and data required to exponentially expand the boundaries of materials science to meet the needs of Industry 4.0.