AISI D7 High-Carbon Cold-Work Tool Steel
AISI D7 — high-V D3 with 4 % V, highest abrasive wear in D-series. Compare with D2, D5 for granulator rotors on filled plastics and mineral wool.
AISI D7 (UNS T30407) is a vanadium- and molybdenum-enriched D3 (4 % Cr, 4 % V, 1 % Mo). The high vanadium content (vs D3/D5) produces a significant population of very hard VC carbides that give the highest abrasive wear resistance in the standard D-series — at the cost of grindability. Used on granulator rotors crushing highly abrasive feedstock (filled plastics, mineral wool).
Standard composition: C 2.15–2.50 %, Cr 11.5–13.5 %, Mo 0.70–1.20 %, V 3.80–4.40 %, Mn ≤ 0.60 %, Si ≤ 0.60 %, balance Fe
Hardness: Annealed HB 235–262; hardened HRC 58–64
Heat treatment: Austenitise 1,010–1,050 °C, air cool, double temper 150–200 °C
Properties: Excellent wear resistance from the high V content (4 %). Very difficult to grind — the V carbides chew up abrasive wheels. Toughness lower than D2. Use only when wear is the dominant failure mode.
Applications: Slitter blades on ceramic, fired-ferrite magnets, and sintered carbide blanks; brick and tile cutting; wear parts in abrasive environments.
Cross-reference: ≈ DIN 1.2380.
See also.
