SYMPOSIA PAPER Published: 01 January 1978
STP28727S

Corrosion-Fatigue Behavior of Coated 4340 Steel for Blade Retention Bolts of the AH-1 Helicopter

Source

The main rotor blade bolt for the 540 helicopter rotor system of the AH-1G, UH-1C, and UH-1M helicopters is proposed to be improved by substituting a plasma-sprayed tungsten carbide coating on the outer shank of the 4340 steel bolt for the present cadmium or chromium plate. This study was undertaken to determine the effects of these coating systems on the fatigue behavior of 4340 steel in environments likely to be encountered in service. Both axial tension-tension and rotating bending fatigue testing of coated specimens were carried out in air and in 3.5 percent sodium chloride (NaCl) solution. The NaCl environment causes reductions in fatigue strength of bare and coated 4340 steel. The severity of the degradation depends on the coating applied and the type of fatigue test utilized.

Author Information

Levy, M
Department of the Army, Army Materials and Mechanics Research Center, Watertown, Mass
Morrossi, JL
Department of the Army, Army Materials and Mechanics Research Center, Watertown, Mass
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Details
Developed by Committee: E08
Pages: 300–312
DOI: 10.1520/STP28727S
ISBN-EB: 978-0-8031-4714-0
ISBN-13: 978-0-8031-0314-6