H13 Die Steel

2. Forging of H13 Tool Steel Heating for forging must be done slowly and uniformly. Soak through at 1900°-2000°F and reheat as often as necessary, stopping work when the temperature drops below 1650°F. After forging, cool slowly in lime, mica, dry ashes or furnace. H-13 should always be annealed after forging.

3. Heat Treatment for H13 Tool Steels

• Annealing

Heat slowly to 1550°-1650°F, hold until entire mass is heated through, and cool slowly in the furnace (40F per hour) to about 1000°F, after which cooling rate may be increased. Suitable precautions must be taken to prevent excessive carburization or decarburization.

• Stress Relieving

When desirable to relieve the strains of machining, heat slowly to 1050°-1250°F, allow to equalize, and then cool in still air (Strain Relieving).

• Preheat Prior to Hardening

Warm slightly before charging into the preheat furnace, which should be operating at 1400°-1500°F.

• Hardening

H13 tool steel is a steel having very high hardenability and should be hardened by cooling in still air. The use of a salt bath or controlled atmosphere furnace is desirable to minimize decarburization, and if not available, pack hardening in spent pitch coke is suggested. The temperature employed is usually 1800°-1850°F, depending on size section.

• Quenching

Quench in still air or dry air blast. If complicated forms are to be hardened, an interrupted oil quench can be used. Quench part in oil and remove from bath when it just loses its color (1000°-1100°F). Finish cooling to below 150°-125°F in air, then temper immediately.

• Tempering

Tempering practice may vary with size and application, but is usually performed in the range of maximum secondary hardness or higher. Double tempering is recommended. The results below is H13 that was air quenched from 1800°F and tempered for 4 hours at various temperatures. The results may be used as a guide, keeping in mind that parts of heavy section or mass may be several points lower in hardness.