Fatigue Cracking of a Forged 4337 Steel Master Connecting Rod Because of Nonmetallic Inclusions
The master connecting rod of a reciprocating aircraft engine revealed cracks during routine inspection. The rods were forged from 4337 (AMS 6412) steel and heat treated to a specified hardness of 36 to 40 HRC. H-shaped cracks in the wall between the knuckle-pin flanges were revealed by visual examination. The cracks were originated as circumferential cracks and then propagated transversely into the bearing-bore wall. No inclusions in the master rod were detected by magnetic-particle and x-ray inspection. Three large inclusions lying approximately parallel to the grain direction and fatigue beach marks around two of the inclusions were revealed by...
Fatigue Cracking of a Forged 4337 Steel Master Connecting Rod Because of Nonmetallic Inclusions, ASM Failure Analysis Case Histories: Air and Spacecraft, ASM International, 2019, https://doi.org/10.31399/asm.fach.aero.c0047856
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