The effect of L-T and S-T orientations on FCGR is here in studied in 7050-T7451 and 2050-T8 aluminum alloys. The Low-cycle fatigue tests and hardness measurements have shown that specimen orientation has a minor effect on material plastic hardening. Lower FCG rates are obtained for both materials in the L-T orientation, which can be associated to the resistance at grain boundaries. The larger cyclic plastic zone attained in the L-T direction leads to an increase of the plasticity inducing crack closure. Crack deflection observed for L-T direction also affects the FCGR due to roughness inducing crack closure, longer crack path and lower effective ΔK.

LT 和 ST 取向对 FCGR 的影响在 7050-T7451 和 2050-T8 铝合金中进行了研究。低周疲劳试验和硬度测量表明，试样取向对材料塑性硬化的影响很小。两种材料在 LT 取向上都获得了较低的 FCG 率，这可能与晶界处的电阻有关。在 LT 方向获得的较大的循环塑性区导致塑性增加，导致裂纹闭合。由于粗糙度导致裂纹闭合、裂纹路径较长和有效 ΔK 较低，在 LT 方向观察到的裂纹偏转也会影响 FCGR。