AISI D3 High-Carbon Cold-Work Tool Steel

AISI D3 (UNS T30403, DIN 1.2080, JIS SKD1) is a higher-carbon variant of D2 (2.0–2.35 % C vs D2 1.4–1.6 % C), with proportionally more M₇C₃ primary carbides. It gives the highest wear resistance in the D-series but the lowest toughness (Charpy 15–25 J vs D2 20–30 J), and cannot be water-quenched. Used on highly abrasive substrates — ceramic, glass fibre, rock-wool insulation.

Standard composition: C 2.00–2.35 %, Cr 11.0–13.0 %, Mo ≤ 0.80 %, V ≤ 0.50 %, Mn ≤ 0.60 %, Si ≤ 0.60 %, balance Fe

Hardness: Annealed HB 217–248; hardened HRC 58–64

Heat treatment: Austenitise 950–980 °C, oil or air cool, double temper 150–200 °C

Properties: Very high wear resistance from the M₇C₃ primary carbides (larger fraction than D2). Lower toughness than D2 (Charpy 15–25 J). Deep-hardenable but with more distortion than D2. Cannot be cooled in water — air or oil only.

Applications: Slitter blades on abrasive paper, ceramic, glass fibre and rock-wool insulation; drawing dies; powder-compaction tooling; cold-extrusion dies for brass.

Cross-reference: ≈ JIS SKD1, DIN 1.2080, GB Cr12, BS BD3.

See also.