Terminology

TEMPERS

Overview
O: Annealed / Fully softened, maximum formability.
F: As fabricated / Raw material after rolling, not annealed.
H: Strain hardened / Strengthened by work hardening through cold forming.
T: Heat treated / Strengthened by precipitation hardening.

1st Digit (Method)
H1x: Cold forming only
H2x: Cold forming + partial annealing
H3x: Cold forming + stabilizing anneal
H4x: Cold forming + prepared for paint hardening

2nd Digit (Hardness Grades)
Hx2: Quarter hard ¼ / High formability
Hx4: Half hard 2/4 / Balance point
Hx6: Three-quarter hard ¾ / Strength priority
Hx8: Full hard 4/4 / Minimum formability
Hx9: Extra hard / Special applications

3rd Digit (Modification)
Hxx1: Slight correction
Hxx2: Alternative tolerance
Hxx3: Stabilized variant
Hxx4: Stretch + correction (tab stock)
Hxx6: Marine grade stabilized
Hxx7-9: Special manufacturer variant