Selection of Tool Steel for Shears
Shearing is a process used to separate sheet, plate, or bar stock by forcing material to fracture along a defined line. In operation, shear blades are subjected to high contact pressure and repeated sliding against the workpiece.
In most cases, blade failure is driven by two mechanisms: edge wear from abrasion and edge damage, such as chipping or spalling, from impact. Under hot-shearing conditions, additional thermal exposure leads to softening and surface cracking, further accelerating edge degradation.
Selection Factors
Selecting tool steel for shears requires matching material properties to the dominant failure mode in the application, rather than pursuing maximum hardness alone.
Impact Toughness vs. Wear Resistance
Shear blades experience intermittent impact during cutting, especially when processing thick sections or high-strength materials. If toughness is insufficient, the cutting edge will chip or fracture.
At the same time, continuous sliding contact causes abrasive wear. Increasing hardness improves wear resistance but reduces toughness. The correct balance depends on whether failure is dominated by edge chipping or gradual wear.
Compressive Strength
During cutting, the blade edge is subjected to extremely high localized compressive stress. If the steel lacks sufficient compressive strength, the edge plastically deforms, resulting in rounding and loss of cutting accuracy.
Thermal Stability and Fatigue Resistance
In hot shearing, blades are repeatedly heated and cooled. The steel must retain hardness at elevated temperatures to avoid rapid wear and resist thermal fatigue to prevent surface cracking. Without these properties, edge failure occurs quickly even if the initial hardness is adequate.
Recommended Tool Steels
AISI S7 Tool Steel Supplier | DIN 1.2355
S7 is used in applications where impact loading is the primary cause of failure. It provides very high toughness, which reduces the risk of edge chipping and breakage under heavy or interrupted cutting conditions.
With a typical working hardness of 56–58 HRC, S7 maintains structural integrity under load. It is suitable for thick sections, high-impact shearing, and conditions where blade failure occurs suddenly rather than through gradual wear. Its wear resistance is lower than that of high-carbon cold-work steels, so it is not ideal for highly abrasive materials.
AISI D2 Tool Steel | 1.2379 | SKD11
D2 is selected when abrasive wear is the dominant factor limiting blade life. Its high carbon and chromium content form a large volume of hard carbides, which resist wear and maintain edge sharpness.
At 58–60 HRC, D2 provides high compressive strength and strong resistance to edge deformation. It is suitable for long production runs involving abrasive materials or clean, stable cutting conditions with limited impact. Due to its lower toughness, it is not recommended where chipping is a frequent failure mode.
AISI S1 Tool Steel | 1.2550 | SKS41
S1 is used when both impact loading and moderate temperature are present. It offers a balance between toughness and resistance to softening at elevated temperatures.
Depending on the application, S1 is typically used at 54–57 HRC for cold shearing or 44–52 HRC for hotter conditions. It is suitable for mixed-use scenarios where neither wear nor impact alone dominates, and where cold-work or hot-work steels alone do not provide stable performance.
H13 Tool Steel Supplier | 1.2344 | SKD61
H13 is used in continuous hot-shearing operations where temperature effects control tool life. It maintains hardness at elevated temperatures and resists thermal fatigue caused by repeated heating and cooling.
At 44–52 HRC, H13 provides a combination of hot strength and toughness. It is suitable for sustained contact with heated materials, where cold-work steels would soften rapidly or develop thermal cracks.
Summary Table
| Tool Steel Grade | Typical Hardness | Primary Advantage for Shears |
| AISI S7 | 56–58 HRC | High toughness for impact-heavy applications |
| AISI D2 | 58–60 HRC | High wear resistance for abrasive materials |
| AISI S1 | 44–57 HRC | Balanced performance under mixed conditions |
| AISI H13 | 44–52 HRC | Stability in hot-shearing environments |