The effect of increasing strength through grain refinement and solid solution or precipitation strengthening by microalloying additions on near-threshold fatigue behavior has been investigated in HSLA-1 which has 0. 07%C, 0. 51%Mn and 0. 014%Nb and an as-received yield strength of 365 MPa. HSLA-2 has 0. 06%C, 0. 35%Mn and 0. 03%Nb and an as-received yield strength of 415 MPa. Results of fatigue crack propagation tests indicate dependence of crack propagation rates and threshold stress intensities on microstructure, load ratio (R) and test temperature. The dependence of fatigue thresholds on R ratio appears to be closure controlled; the effect of test temperature appears to be a combined contribution of yield strength and closure. The differences in the fatigue crack propagation behavior result from variations in Nb(CN) particle contents, size and distribution.
|Original language||English (US)|
|Title of host publication||Unknown Host Publication Title|
|Number of pages||13|
|State||Published - Dec 1 1984|