Stress Corrosion Susceptibility of Ultra-High Strength Steels for Naval Aircraft Applications PDF Download

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Languages : en
Pages : 47

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Book Description
Low alloy quenched and tempered steels used in current Naval aircraft applications, particularly the ultrahigh strength steels used in landing gear, have characteristically small critical flaw sizes and extreme susceptibility to stress corrosion cracking in a shipboard environment. Newly developed steels which develop ultrahigh strengths with secondary hardening based on precipitation of M2C carbides offer significantly larger critical flaw sizes; and while susceptible to stress corrosion cracking, their susceptibility is substantially less than that of low alloy steels. A long term test program conducted by the Naval Air Warfare Center Aircraft Division Warminster has characterized the stress corrosion cracking susceptibility of the newly developed steels. Results of the program have shown that, compared to low alloy steels, the newly developed steels show substantially reduced susceptibility to stress corrosion at short exposure times and maintain their advantage to a lesser extent at exposure times up to 1 0,000 hours. The test program has demonstrated also that 1,000 hour exposure times, characteristically used for stress corrosion tests of steels, are insufficient to establish stress corrosion thresholds (Klscc), as numerous failures were observed at exposure times between 1,000 and 1 0,000 hours. Fracture characteristics of the stress corrosion failures are shown.