H11 tool steel is a 5% chromium hot work tool steel that is represented by its excellent impact toughness. Chromium hot-work tool steels are designated as group H steels according to the AISI classification system, and specified in ASTM A681 standard. The most commonly used chromium hot-work steels are H11 tool steel, H12 tool steel, and H13 steel, within the series from H1 to H19.

If we compare between H11 and H13, H11 tool steel consists of less vanadium than the commonly used H13 hot work tool steel. This gives H11 steels the higher toughness, with some reduction in wear resistance and temper resistance. H11 tool steel is a deep-hardening, air-hardening steel and H11 alloy steel could be deep hardened by heat treatment and air-quenching. That gives minimal size change during heat treatment. H11 how work steel also has super resistance to thermal fatigue cracking and superb resistance to gross cracking and thermal shock when water cooled in service.