**Symbols Used**

ASTM—American Society of Testing and Materials KT diagram—Kitagawa Takahashi μ—Ratio of frictional stress to applied stress. BCS model—Bilby, Cottrell, and Swindon model a—Crack Length

*Crystals* **2020**, *10*, 358

ac—Critical Crack length σy—Normal Stress ET—Total Energy of the System ES—Self Energy of all dislocations EI—Interaction energy of all dislocation Eγ—Surface energy Eσ—Work done by applied stress τxy—Lattice frictional stress αc—Crack mouth angle Kt—Elastic Stress Concentration Factor ρ—Notch tip radius KSC—Stress intensity factor for short crack Kth—Threshold stress intensity factor for crack growth KIC—Fracture Toughness KISCC—Stress Corrosion Crack Growth Threshold Kpl—Stress intensity factor for short crack in the elastic plastic notch tip field. ΔKth—Fatigue crack growth threshold Stress intensity range. σapl—Applied Stress σys—Yield Stress σe—Endurance Stress σFS—Fracture Stress E—Elastic Modulus γ—Surface Energy ν—Poisson ratio
