Accession Number:

ADA605272

Title:

Coated 4340 Steel

Descriptive Note:

Technical rept.

Corporate Author:

NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD

Report Date:

2013-08-26

Pagination or Media Count:

36.0

Abstract:

A study was conducted to evaluate the effects of three coating systems on the mechanical property, fatigue, and stress corrosion cracking SCC of 4340 steel. These coating systems were electroplated cadmium and chromate passivation, cadmium with chromate primer, and cadmium, chromate primer and polyurethane topcoat. The three coating systems reduced the bending strength and hardness of the base metal, 4340 steel, in air. Their respective effects on the fatigue resistance of bare 4340 steel were similar in both of the employed environments, air and 3.5 NaCl solution. In addition, they were found to reduce the fatigue resistance of bare 4340 steel in air, but protect the substrate partly from aggressive environmental attack in 3.5 NaCl solution. The reduction of bending strength, hardness and fatigue resistance in air is attributed to hydrogen embrittlement, induced by Cd-electroplating. The SCC resistance was found to be enhanced more by each additional coating on the initial electroplated cadmium.

Subject Categories:

  • Coatings, Colorants and Finishes
  • Metallurgy and Metallography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE