Evaluation of the Relative Hydrogen Embrittlement Susceptibility of ESR 4340 and Its Heat Treat Distortion Properties
Abstract
A test program to compare the relative hydrogen embrittlement susceptibility of remelted 4340 steel with ESR and VAR methods has been completed. The issue of ESR's susceptibility to hydrogen embrittlement arose when unexpected difficulties were experienced with critical control system actuator pistons on the helicopter programs. High strength (above 260 Ksi) 4340 ESR steel is used in these applications because of 4340 ESR's demonstrated superior ballistic tolerance. Three heat treat levels and two grain orientations were evaluated; and three test methods were applied to measure embrittlement susceptibility. A significant reduction in embrittlement susceptibility is associated with lower strength approximately 43 HRC) as compared to high strength approximately 53 HRC) 4340. The short transverse grain direction is more susceptible than the longitudinal direction, and all test methods indicated that VAR is less susceptible to hydrogen embrittlement than ESR. A parallel effort during the test program focused on heat treat distortion difference between ESR and VAR 4340. While a difference in distortion propensity cannot be ruled out on the basis of test results, it can be concluded that such differences between ESR and VAR are small compared to heat treatment parameters affecting distortion.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1982
- Accession Number
- ADA122178
Entities
People
- C. Beneker
- L. Raymond