a	Crack length
A(T,ν,th)	Constant in mid-ΔK fatigue crack growth rate equation
b	Strain range exponent in short-crack creep-fatigue crack growth equation
B'	Constant in short-crack creep-fatigue crack growth equation
C, F, CF	Creep; Fatigue; Creep-fatigue
C*	Parameter characterising stress and strain rate fields at tip of crack in material deforming due to creep
da/dN	Total crack growth rate (per cycle)
(da/dN)C, (da/dN)F	Crack growth rate (per cycle) due to creep and fatigue respectively
DC, DF	Total creep damage fraction; Total fatigue damage fraction
D(εR)	Constant in creep crack growth law, dependent on creep-rupture ductility
kp	Parabolic oxide growth law constant
K, ΔK	Stress intensity factor; Range of stress intensity factor
Keq	Equivalent stress intensity factor (K with a plasticity correction, similar to J)
LCF	Low cycle fatigue
Lf, Lt	Cumulative length of cracked grain boundaries per unit length of section; Total length of grain boundaries in the same area (being characteristic of the grain size and shape)
J	Parameter characterising stress and strain fields at tip of crack in material deforming plastically
m	Exponent in mid-ΔK fatigue crack growth rate equation
N, Ni	Number of cycles; Number of cycles to crack initiation
N + T	Normalised and tempered
Q	Crack size exponent in short-crack creep-fatigue crack growth rate equation
rp	Size of cyclic plastic zone
SENB	Single edge notched bend (specimen)
t, th, tR	Time; Hold time; Time to creep-rupture
TMF	Thermo-mechanical fatigue
x	Oxide thickness
ε, Δε	Strain; Strain range
εR	Creep-rupture ductility
Φ	Microstructural condition parameter
γ	C* exponent in creep crack growth law
ν	Frequency