Cadmium plated 35NCD16 steel threaded fasteners are used for aerospace applications. One such fastener parted into two pieces during application of required torque. The fracture surface of the failed fastener consisted of two distinct regions, a bright region at the center encircled by a relatively dark region. The dark region spread all along the periphery of the fracture surface. Fractography revealed that the central bright region consisted of dimples, while the dark region consisted of intergranular facets. From the evidences it was concluded that the fastener failed due to hydrogen embrittlement. The possible sources for hydrogen entrapment in the material were the uncontrolled furnace atmosphere during long spheroidization treatment and inadequate baking after cadmium plating.
Hydrogen embrittlement of 3.5Ni-1.5Cr-0.5Mo steel fastener
Wasserstoffversprödung eines Befestigungselementes aus Stahl 3,5Ni-1,5Cr-0,5Mo
Engineering Failure Analysis ; 15 , 5 ; 431-439
2008
9 Seiten, 12 Bilder, 1 Tabelle, 5 Quellen
Aufsatz (Zeitschrift)
Englisch
Steel, Carburizing 3.5ni 1.5cr (.14 - .20c)
SAE Technical Papers | 1946
Steel, Carburizing 3.5ni 1.5cr (.11 - .17c)
SAE Technical Papers | 1946
STEEL BARS, FORGINGS, AND TUBING 1.5Cr - 3.5Ni (0.07 - 0.13C) (SAE 3310)
SAE Technical Papers | 1967
Steel Bars, Forgings, and Tubing 1.5Cr - 3.5Ni (0.07 - 0.13C) (SAE 3310)
SAE Technical Papers | 2006