Skip to Main Content
ASM Failure Analysis Case Histories

Handbook of Case Histories in Failure Analysis

Edited by
Khlefa A. Esaklul
Khlefa A. Esaklul
Search for other works by this author on:
ASM International
Volume
2
ISBN electronic:
978-1-62708-215-0
Publication date:
1993
Book Chapter

Hydrogen-Assisted Stress Cracking of Carburized and Zinc Plated SAE Grade 8 Wheel Studs

By
Roy G. Baggerly
Roy G. Baggerly
Kenworth Truck Co.
Search for other works by this author on:
Published:
1993
Page range:
396 - 400

Abstract

Several case-hardened and zinc-plated carbon-manganese steel wheel studs fractured in a brittle manner after very limited service life. The fracture surfaces of both front and rear studs showed no sign of fatigue beach marks or deformation in the form of shear lips that would indicate either a fatigue mechanism or ductile overload failure. SEM analysis revealed that the mode of fracture was intergranular decohesion, which indicates an environmental influence in the fracture mechanism. The primary fracture initiated at a thread root and propagated by environmentally-assisted slow crack growth until final fracture. The natural stress concentration at the thread root, when tightened to the required clamp load concomitant with the presence of cracks in the carburized case, was sufficient to exceed the critical stress intensity for hydrogen-assisted stress cracking (HASC). The zinc plating exacerbated the situation by providing a strong local corrosion cell in the form of a sacrificial anode region adjacent to the cracked thread. The enhanced generation of hydrogen in a corrosive environment subsequently lead to HASC of the wheel studs.

You do not currently have access to this content.
Don't already have an account? Register

Roy G. Baggerly, 1993. "Hydrogen-Assisted Stress Cracking of Carburized and Zinc Plated SAE Grade 8 Wheel Studs", Handbook of Case Histories in Failure Analysis, Khlefa A. Esaklul

Download citation file:


Close
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal