Bend Radius Chart (Steel, Aluminum & Copper)

What Is Bend Radius?

The bend radius refers to the inner radius of curvature in a bent metal part, where ‘t’ represents the material thickness. This parameter is crucial in sheet metal fabrication and structural design.

During the bending process, the material undergoes significant stress distribution. The outer layer of the bend experiences tensile stress and stretches, while the inner layer compresses. The severity of this deformation is inversely proportional to the bend radius; a smaller inner radius results in more extreme material stretching and compression for a given material thickness.

If the tensile stress on the outer bend surface exceeds the material’s ultimate tensile strength, it can lead to cracking or fracture. Consequently, the structural design of bent components should carefully consider the minimum allowable bend radius to prevent material failure.

The minimum bend radius varies depending on the material properties, particularly its ductility and work hardening characteristics. Here are some guidelines for common materials used in metal fabrication:

• For low-carbon steels and austenitic stainless steels such as 08, 08F, 10, 10F, DX2, SPCC, E1-T52, 0Cr18Ni9, 1Cr18Ni9, 1Cr18Ni9Ti, and aluminum alloys like 1100-H24, as well as copper alloys like T2, the minimum bend radius is typically 0.4t.
• Medium-carbon steels and some structural steels including 15, 20, Q235, Q235A, and 15F require a slightly larger minimum bend radius of 0.5t.
• Higher-carbon steels and higher-strength structural steels such as 25, 30, and Q255 necessitate a minimum bend radius of 0.6t due to their reduced ductility.
• For high-strength steels and work-hardening stainless steels like 65Mn, 60SiMn, 1Cr17Ni7 series (including 1Cr17Ni7-Y and 1Cr17Ni7-DY), SUS301, 0Cr18Ni9, and SUS302, the minimum bend radius increases significantly to 2.0t due to their high yield strength and tendency to work harden.

It’s important to note that these are general guidelines, and factors such as grain orientation, surface finish, and bending direction relative to the rolling direction can influence the actual minimum bend radius. In precision applications or when working with critical components, it’s advisable to conduct bending tests or consult material-specific data sheets for more accurate values.

Bend Radius Chart