In high-pressure, high-temperature industrial environments, molds face relentless stress. Substandard materials lead to frequent replacements and soaring maintenance costs. The solution? AISI H13 hot-work tool steel from Cincinnati Tool Steel—a material engineered to endure extreme conditions while extending mold life and boosting productivity.

Renowned for its exceptional red hardness, wear resistance, and thermal crack resistance, AISI H13 is a vacuum-degassed steel that delivers uniform composition, consistent heat treatment response, and prolonged service life. Its dominance in aluminum and zinc die-casting molds is unmatched, while its ability to withstand rapid cooling during high-temperature operations makes it equally valuable for extrusion dies.

• Die-Casting Excellence: The preferred material for aluminum and magnesium die-casting molds, H13 also performs reliably in prolonged zinc production runs and is widely used for sliders and cores in tool assemblies.
• Plastic Mold Superiority: With a hardness range of 45–52 HRC, H13 excels as a plastic mold steel. Its high polishability makes it ideal for optical lenses and cutlery molds.
• Extreme Environment Stability: H13 thrives in applications demanding rapid cooling cycles, high red hardness, and thermal crack resistance—including zinc, white metal, aluminum, and magnesium die-casting; extrusion dies; trimming tools; hot shear blades; and similar thermal processing equipment.

In fully annealed condition, H13 demonstrates good machinability, scoring 75 on the machinability index (compared to 100 for 1% carbon tool steel).

When air-cooled from proper hardening temperatures, H13 typically expands by 0.001 inch per inch of cross-section.

Heat to 1600°F, soak for one hour per inch of maximum thickness, then furnace-cool at 30°F per hour to 900°F before air cooling. Proper annealing in neutral packing within sealed containers yields a maximum Brinell hardness of 207.

Preheat thoroughly at 1300–1400°F in controlled atmosphere, then heat to 1850°F with one-hour soak per inch of cross-section. Air-quench and temper immediately. For maximum hardness, oil quenching is possible but carries cracking risks similar to oil-hardening tool steels.

For hot-work applications, temper to 38–48 HRC. Die-casting molds typically use 44–48 HRC (achieved at ~1100°F). For impact resistance, temper near 1150°F for 40–44 HRC. Maintain temperature for two hours per inch of cross-section, with double tempering recommended—especially where thermal cracking is a concern.

This vacuum-degassed steel combines purity with uniform microstructure, delivering predictable heat treatment responses and extended service life under thermal cycling. Its balanced chemistry—particularly the 5.25% chromium and 1.05% vanadium—creates a robust matrix of carbides that resist softening at elevated temperatures while maintaining toughness.