AISI A8 Air-Hardening Cold-Work Tool Steel
AISI A8 — high-toughness air-hardening cold-work tool steel for impact loading. Compare with A2, A6, S7 for shear blades on thick plate.
AISI A8 (UNS T30108) is a high-toughness air-hardening cold-work tool steel with 5 % Cr and 1.5 % Mo plus W additions for impact resistance. Used where A2/A6 wear life is sufficient but impact loading is the dominant failure mode — shear blades on thick plate, granulator bed knives under shock.
Standard composition: C 0.50–0.60 %, Cr 4.75–5.50 %, Mo 1.15–1.65 %, W 1.00–1.50 %, V 0.30–0.50 %, Mn ≤ 0.50 %, Si 0.75–1.10 %, balance Fe
Hardness: Annealed HB 217–248; hardened HRC 56–60
Heat treatment: Austenitise 980–1,010 °C, air cool, double temper 175–540 °C
Properties: Better hot hardness than A6 from the W addition. Toughness similar to A6. Used for hot-work applications that do not need H13-class hot hardness.
Applications: Cold-header dies, punches for thick plate, shear blades on tough substrate, hot-piercing punches for billet.
Cross-reference: ≈ DIN 1.2343 (similar).
See also.
