A2 Tool Steel

A2 tool steel is a 5% chromium medium alloy cold work tool steel possessing sufficient hardenability to be air hardened to 60 Rc surface hardness level with good depth of hardening. This widely used tool steel has low distortion in heat treatment, good machinability, good toughness for severe service, high abrasion resistance, and deep hardening properties in large sections. A2 has a fully spheroidized structure and has exceptionally low inclusion levels. A2 is available in de-carb free rounds, flats and squares, as well as drill rod and ground flat stock.

ANALYSIS

A.I.S.I. A2 conforms to ASTM A681, DIN 1.2363, SAE J437, J438

APPLICATIONS

Typical applications for A2 tool steel are blanking, forming, and trim dies, stamping dies, coining dies, thread roller dies, knurls, knurling tools, mandrels, master hobs, cold forming tools, spindles, shear blades, slitter blades, molds, punches, block and ring gauges, punch plates, reamers, brick mold liners, forming rolls, etc

HEAT TREATING

FORGING

Heating for forging must be done slowly and uniformly. Soak through at 1900-2000F and reheat as often as necessary, stopping work when the temperature drops below 1650F. After forging, cool slowly in lime, mica, dry ashes or furnace. A2 should always be annealed after forging.

ANNEALING

Heat slowly to 1550-1600F, hold until entire mass is heated through, and cool slowly in the furnace (40F per hour) to about 1000F, 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 1050-1250F, allow to equalize, and then cool in still air (Strain Relieving).

PREHEAT PRIOR TO HARDENING

Preheat slowly to 1350-1450F and hold at this temperature until part is uniformly heated.

HARDENING

After thorough preheating, heat to 1750-1800F. Hold the work piece at the hardening temperature until it is completely and uniformly heated.

QUENCHING

A2 is an air hardening steel and will develop full hardness on cooling in still air. To avoid scaling of the work piece surface, controlled atmosphere or vacuum furnaces are recommended. If these types of furnaces are not available, salt baths or wrapping the part in stainless steel foil will provide a degree of surface protection in the hardening process, Parts should be allowed to cool to 150F, or to where they can be held in the bare hand, and then temper immediately.

TEMPERING

The tempering temperature may be varied according to the desired hardness. If maximum hardness is desired, tempering should be in the range of 300-400F, but if a lower hardness is acceptable, tempering at 950F will give the optimum combination of hardness and toughness. The Rockwell C hardness obtained on specimens 1 inch square when quenched in air from 1775F and tempered at various temperatures, held for 4 hours, are as follows:

TOLERANCES

SPEEDY METALS ITEMS