Cold extrusion process and steel selection

Cold extrusion is a process that deforms metal by stabilizing pressure. It is divided into forward and backward extrusion, of which cold impact extrusion is a special form. It requires a high steel compressive strength (hardness), often at the expense of toughness. Commonly used steels such as A2, D2, and M2 have low toughness (ratings 1-5), and the dies need to be prestressed and fitted with shrink rings made from H11 steel to increase durability. M2 steel provides longer mold life, while the more ductile H11 steel (ratings 6-9) is recommended for best results in difficult cases where cracking is a concern.

Cold Extrusion Tool Steel Recommendation Form

Table 1: Tool Steels for Cold Extrusion – Punches

Steel	Wear Resistance (Rating)	Toughness (Rating)	Working Hardness (HRC)
T15	9	1	64-66
M4	9	2	64-66
D4	8	1	62-64
D2	8	2	60-62

Table 2: Tool Steels for Cold Extrusion – Punch Shank or Mandrel

Steel	Wear Resistance (Rating)	Toughness (Rating)	Working Hardness (HRC)
A2	6	5	56-58
S1	4	3	56-58
S5	2	8	56-58

Table 3: Tool Steels for Cold Extrusion – Die Insert

Steel	Wear Resistance (Rating)	Toughness (Rating)	Working Hardness (HRC)
T15	9	1	65-67
M4	9	2	64-66
D4	8	1	62-64
M2	7	3	64-65
D2	8	2	60-62

Table 4: Tool Steels for Cold Extrusion – Die Base

Steel	Wear Resistance (Rating)	Toughness (Rating)	Working Hardness (HRC)
A2	6	5	54-56
S1	4	8	54-56
L6	3	6	54-56
O1	4	3	54-56

Table 5: Tool Steels for Cold Extrusion – Die Holder

Steel	Wear Resistance (Rating)	Toughness (Rating)	Working Hardness (HRC)
H11	3	9	48-50

Table 6: Tool Steels for Cold Extrusion – Knockout Pin

Steel	Wear Resistance (Rating)	Toughness (Rating)	Working Hardness (HRC)
H11	3	9	53-55
S5	2	8	54-56
L6	3	6	54-56
O1	4	3	54-56
S1	4	8	54-56

Table 7: Tool Steels for Cold Extrusion – Die Anvil

Steel	Wear Resistance (Rating)	Toughness (Rating)	Working Hardness (HRC)
M4	9	2	60-62
D2	8	2	58-60
A2	6	5	58-60
O1	4	3	58-60