Selection of Tool Steel for Deep Drawing Dies
Deep drawing dies are used in cold-forming operations to convert flat sheet metal into hollow components. The process is typically performed at or near room temperature and rarely exceeds 200°C, so thermal softening does not control tool life.
Instead, failure is governed by contact pressure and sliding friction at the die-workpiece interface. Under these conditions, the dominant failure modes are abrasive wear and adhesive wear (galling). Material transfer to the die surface increases friction, disrupts metal flow, and accelerates surface damage. In practice, the life of a die depends on how well the material resists wear, adhesion, and surface instability under sustained contact.
Selection Factors
Material selection for deep-drawing dies is governed by mechanical loading and frictional behavior rather than temperature.
Resistance to plastic deformation is essential to maintain die geometry under high contact pressure. Once the surface deforms, clearance is lost, and part quality deteriorates rapidly.
Wear resistance must address both abrasion and adhesion. Continuous sliding contact requires a material that resists surface wear while also limiting metal pickup from the workpiece. This typically favors steels with sufficient carbide content, but excessive carbide volume increases brittleness and the risk of chipping.
Hardness improves wear resistance and reduces adhesion, but it must be balanced with toughness. In deep-drawing dies—especially those with small radii or complex geometries—insufficient toughness can lead to edge chipping or cracking.
Because operating temperatures are low, hot hardness is not a selection factor. Material selection should focus on wear resistance, adhesion, and resistance to mechanical damage under pressure.
Recommended Tool Steels
AISI D2 Tool Steel | 1.2379 | SKD11
D2 is the standard choice for long production runs where abrasive wear is the primary concern. Its high carbon and chromium content provide strong resistance to surface wear and deformation.
It performs best when lubrication is stable, and the galling tendency is not severe. In applications with a high risk of adhesion, its performance can decline due to material pickup. Typical working hardness is 58–62 HRC.
AISI A2 Tool Steel | 1.2363 | SKD12
A2 is used when higher toughness and dimensional stability are required. Compared with D2, it offers lower wear resistance but better resistance to chipping and cracking.
It is suitable for dies with complex geometry, higher stress concentration, or moderate production volumes where tool integrity is more critical than maximum wear life. Typical hardness is 57–60 HRC.
AISI O6
O6 is selected when galling is the dominant failure mode. The presence of free graphite reduces friction at the contact interface, limiting adhesion and stabilizing metal flow.
It is particularly effective in difficult drawing conditions where material sticking cannot be controlled through lubrication alone. Typical hardness is 58–62 HRC.
AISI M4
M4 is used in severe drawing conditions where conventional cold-work steels cannot maintain tool life. Its high vanadium carbide content provides superior resistance to abrasion and plastic deformation.
It is typically selected when D2 or A2 shows rapid wear under high-load or high-volume production. Due to lower toughness and higher cost, it is reserved for applications where wear resistance is the limiting factor. Typical hardness is 60–64 HRC.
Summary Table
| Tool Steel Grade | Typical Hardness | Primary Advantage for Deep Drawing |
| AISI D2 | 58–62 HRC | High wear resistance for long production runs |
| AISI O6 | 58–62 HRC | Reduced friction and strong resistance to galling |
| AISI A2 | 57–60 HRC | Better toughness and dimensional stability |
| AISI M4 | 60–64 HRC | Maximum wear resistance under severe conditions |