A6 Tool Steel

A6 de-carb free tool steel is an air hardening tool steel with higher manganese and lower chromium and carbon than A2, offering moderate wear resistance and toughness. It has the advantage of hardening from a lower austenitizing temperature for easy heat treatment. A6 hardens with very little movement or distortion. A6 offers medium resistance to softening at elevated work temperatures, medium to high resistance to decarburization, and has good machinability. One main advantage of A6 is its deep hardening with high safety in hardening.


A.I.S.I. A6 conforms to ASTM A681


Typical applications for A6 tool steel are blanking dies, forming dies, trim dies, stamping dies, coining dies, notching dies, bending tools, rim rolls, punches, cams, thread roll dies, spindles, retaining rings, master hobs, precision tools, mandrels, compression molds, plastic molds requiring high hardness, ball screws, lead screws, general purpose tooling, etc



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 1600°F. After forging, cool slowly in lime, mica, dry ashes or furnace. A6 should always be annealed after forging.


Heat slowly to 1350°-1375°F, hold until entire mass is heated through, and cool slowly in the furnace (20F per hour) to about 1000°F, after which cooling rate may be increased. Suitable precautions must be taken to prevent excessive carburization or decarburization.


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).


Preheating is often not necessary depending on the size and complexity of the part. If a preheat is desirable, a 1200°-1250°F temperature should be used. Heat slowly.


Parts at room temperature or as pre-heated should be placed in a hardening furnace operating at 1525°-1600°F. After parts have reached the furnace temperature, hold 20 minutes for small parts and up to 45 minutes for large parts


A6 is a deep hardening tool steel and will reach full hardness by cooling in freely circulating air.


A single temper (one hour at temperature for small pieces; proportionately longer time for larger sizes) is usually all that is required with tempering carried out in the range of 300°-1000°F. For most applications, the best combination of hardness and toughness is accomplished at 350°-400°F. Specimens 1 inch square by 3 inches long were air hardened from 1550°F and tempered at various temperatures for two hours. The resulting harnesses were as follows:

Tempering Temperature F Rockwell C Tempering Temperature F Rockwell C
300 62 800 52
350 60 900 51 400 59 1000 49
500 58 1100 47
600 56 1200 41
700 54    


A6 de-carb free rounds are produced .015-.035 oversize. A6 de-carb free flats and squares are produced .015-.035 oversize on thickness, and widths are milled or cut oversize sufficiently to clean to nominal size.


1.625" 1/2" {A} Rd A-6 De-Carb Free Tool Stee 5/8" {A} Rd A-6 De-Carb Free Tool Stee
3/4" {A} Rd A-6 De-Carb Free Tool Stee 1" {A} Rd A-6 De-Carb Free Tool Stee 1-1/4" {A} Rd A-6 De-Carb Free Tool Stee
1-1/2" {A} Rd A-6 De-Carb Free Tool Stee 1-3/4" {A} Rd A-6 De-Carb Free Tool Stee 2" {A} Rd A-6 De-Carb Free Tool Stee
2-1/4" {A} Rd A-6 De-Carb Free Tool Stee 2-1/2" {A} Rd A-6 De-Carb Free Tool Stee 2-3/4" {A} Rd A-6 De-Carb Free Tool Stee
3" {A} Rd A-6 De-Carb Free Tool Stee 3-1/4" {A} Rd A-6 De-Carb Free Tool Stee 3-1/2" {A} Rd A-6 De-Carb Free Tool Stee
4" {A} Rd A-6 De-Carb Free Tool Stee 8" {A} Rd A-6 De-Carb Free Tool Stee