Accession Number:

AD0661958

Title:

HYDROGEN-STRESS CRACKING OF 17-4PH STAINLESS,

Descriptive Note:

Corporate Author:

AEROSPACE CORP EL SEGUNDO CALIF LAB OPERATIONS

Personal Author(s):

Report Date:

1967-08-01

Pagination or Media Count:

26.0

Abstract:

The susceptibility of 17-4PH to hydrogen-stress cracking was found to increase as the hardness of the steel increased from 42 to 47 R sub c. Conditions of hydrogen-stress cracking were created by attaching a piece of aluminum 7075-T6 to a stress corrosion test specimen. In the absence of aluminum, under identical test conditions, no stress-corrosion cracking failures were recorded in times up to 1000 hr. Charging the bolts with hydrogen and statically loading the bolts in air produced failure times similar to those obtained with the test samples coupled to the aluminum alloy and periodically immersed in a 3-12 salt solution. When the 17-4PH was over-aged to a hardness of 40 R sub c or less, the susceptibility was eliminated. These variations in hardness did not change the yield point of the bolt as determined by the Johnsons 23 method. Three additional methods of protection against hydrogen-stress cracking were evaluated nickel-cadmium electroplating of the bolts, anodizing the aluminum, and insulating with a lubricant at the aluminumstainless steel interface. Nickel-cadmium plating AMS-2416 the 17-4PH to a thickness of from 0.2- to 0.4- mil nickel0.1- to 0.2- mil cadmium offered no resistance to hydrogen-stress cracking. The remaining two methods proved effective in inhibiting hydrogen-stress cracking under controlled laboratory conditions, but, with poor handling procedures, the dissimilar metal couple could be easily activated and cause failure by hydrogen-stress cracking. Author

Subject Categories:

  • Properties of Metals and Alloys
  • Fabrication Metallurgy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE