Fracture of High-Strength Screws During Installation
-
Published:2019
Abstract
Size M5 x 0.8 mm, class 8.8 metric screws were failing during application, reportedly at the normal installation torque. Investigation (visual inspection, metallographic analysis, and unetched 8.9x fractographs) supported the conclusion that the fasteners failed via ductile overload in the absence of gross defects or embrittlement. It was subsequently determined that a nonapproved lubricant had been used during installation. Tension preloads can be more than twice their normal level on lubricated fasteners because of reduced friction, and in this case, the preload was sufficient to fracture the screws. No recommendations were made.
Fracture of High-Strength Screws During Installation, ASM Failure Analysis Case Histories: Improper Maintenance, Repair, and Operating Conditions, ASM International, 2019, https://doi.org/10.31399/asm.fach.usage.c0090929
Download citation file:
Join Failure Analysis Society
The ASM Failure Analysis Society (FAS) is a community where failure analysis professionals from all over the world can learn and grow in their field.