Symbols	Description	Unit
Rp0.2	Yield strength	MPa
Rm	Ultimate tensile strength	MPa
E	Elastic modulus	GPa
ν	Poisson’s ratio
B	Thickness of specimen	mm
W	Width of specimen	mm
L	Length of specimen	mm
N	Number of cycles
a	Length of propagation crack	mm
Δa	Crack propagation quantity	mm
K	Stress intensity factor	MPa·m1/2
ΔK	Stress intensity factor range	MPa·m1/2
K max	Maximum stress intensity factor	MPa·m1/2
K IC	Plane strain fracture toughness	MPa·m1/2
K J0.2BL	Value of fracture toughness calculated by the J-integral method	MPa·m1/2
KC	Value of fracture toughness calculated by dimple size	MPa·m1/2
J	The experimental equivalent of the J integral	kJ/m2
J0.2BL	Intersection point of the J-Δa resistance curve and the 0.2 mm passivation line	kJ/m2
h	Height of dimple	µm
hl	Height of large dimple	µm
hs	Height of small dimple	µm
d	Diameter of dimple	µm
dl	Diameter of large dimple	µm
ds	Diameter of small dimple	µm
S	Area fraction of dimple
Sl	Area fraction of large dimple
Ss	Area fraction of small dimple