DC01 vs DC04 vs DC06 Fine Blanking | Cold Rolled Low Carbon Steel Comparison

Material Comparison

EN 10130 Cold Rolled Steel Grades Overview

EN 10130 specifies cold rolled low carbon steel flat products for cold forming, with grades DC01 through DC06 in order of increasing formability and decreasing yield strength. These grades represent the most commonly fine blanked materials globally, accounting for approximately 60 percent of all fine blanked parts by weight. The grades differ in chemical composition limits, mechanical property requirements, and annealing treatments.

EN 10130 defines five grades: DC01 (commercial quality, annealed), DC03 (deep drawing quality), DC04 (deep drawing quality, special), DC05 (extra deep drawing quality), and DC06 (extra deep drawing quality, special). For fine blanking, DC01, DC04, and DC06 are most relevant, representing progression from basic quality for simple flat parts to ultra-formable grades for complex multi-stage formed components.

Cold rolled steel fine blanked parts showing different EN 10130 grade applications

Mechanical Properties

Yield Strength, Elongation, r-Value and n-Value

The mechanical properties of EN 10130 grades vary systematically, with each grade representing a compromise between strength and formability. Fine blanking requires sufficient ductility for clean sheared edges while maintaining adequate strength for finished component function.

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Yield and Tensile Strength

DC01 exhibits the highest yield strength at 130 to 260 MPa and tensile strength of 270 to 410 MPa. DC04 offers reduced yield strength of 120 to 210 MPa with tensile strength of 270 to 350 MPa. DC06 provides the lowest yield strength at 100 to 180 MPa and tensile strength of 270 to 330 MPa. Lower yield strength reduces blanking force, minimizes tool wear, and improves edge quality by allowing more plastic deformation before fracture. For functional parts requiring rigidity, DC01 may be preferred despite inferior blanking performance.

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Elongation and Formability

DC01 provides minimum elongation of 28 percent, adequate for simple flat parts. DC04 achieves 34 percent minimum, suitable for moderate post-blanking forming such as flanging. DC06 delivers 38 percent minimum, enabling complex geometries including deep drawn cups. Higher elongation produces larger shear zones and smaller fracture zones, resulting in improved edge finish and reduced post-processing requirements.

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r-Value (Lankford Coefficient)

The plastic strain ratio measures resistance to thinning during deformation. DC01 has no specified r-value. DC04 requires minimum average r-value of 1.3, indicating good drawing performance. DC06 requires minimum 1.6, reflecting superior deep drawing capability. Higher r-values reduce tearing risk at blank edges during forming, particularly for parts with deep draws.

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n-Value (Strain Hardening Exponent)

The strain hardening exponent determines how rapidly material strengthens during deformation. DC04 requires minimum n-value of 0.17, while DC06 requires 0.20. Higher n-values provide better resistance to localized necking, distributing deformation more uniformly. For fine blanking, higher n-values produce more gradual transitions from shear zone to fracture zone, improving edge appearance and reducing burr formation.

Blankability Analysis

Fine Blanking Suitability and Blankability Index

Fine blanked parts from DC01 DC04 and DC06 steels showing edge quality differences

Grade-Specific Suitability

DC01 is best suited for simple flat parts such as washers, spacers, and brackets where post-blanking forming is minimal. Its limited ductility produces a larger fracture zone, acceptable for non-critical edges but may require deburring for functional contact surfaces. DC01 is typically supplied annealed with hardness of 50 to 70 HRB.

DC04 is the preferred grade for general fine blanking requiring balance of blanking performance and moderate formability. It produces excellent sheared edges with 85 to 95 percent shear zone, and provides sufficient ductility for flanging, bending, and shallow drawing. DC04 is the standard recommendation for automotive components such as seat recliner parts, brake caliper brackets, and transmission plates.

DC06 is optimal for complex formed components where the fine blanked edge serves as starting point for multi-stage forming. Ultra-high formability enables deep drawing, severe stretching, and complex bending without edge cracking. Superior edge quality reduces or eliminates preparation before forming, improving process economics for complex automotive and appliance components.

Blankability Index Calculation

The blankability index provides a quantitative measure of fine blanking suitability: BI equals 100 times A divided by Rm, where A is elongation in percent and Rm is tensile strength in MPa. DC01 (28 percent, 340 MPa) yields BI of 8.2. DC04 (34 percent, 310 MPa) yields 11.0. DC06 (38 percent, 300 MPa) yields 12.7. Values above 10 indicate excellent fine blanking performance. Additional factors include strain hardening exponent, grain size, and inclusion content. Fine grain size of DC04 and DC06 (ASTM 7 to 9) promotes uniform deformation and delays crack initiation.

Surface Quality Classes

EN 10130 defines two surface quality classes: Class A and Class B (improved for exposed surfaces). For fine blanking, Class B is strongly recommended because surface defects propagate into sheared edges. Surface roughness Ra should be 0.6 to 1.5 micrometers; slightly rough surfaces (Ra 0.8 to 1.2 micrometers) retain lubricant better than highly polished surfaces. For exposed automotive applications, Class B with controlled roughness provides the best combination of blanking performance and cosmetic acceptability.

Quality Standards

Thickness Tolerance and Dimensional Accuracy

EN 10130 specifies thickness tolerances based on nominal thickness and width. For fine blanking, thickness consistency is critical because die clearance is calibrated to specific thickness.

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EN 10130 Thickness Tolerance

For thicknesses of 0.5 to 4.0 mm, class A tolerance is plus or minus 0.13 mm for 2.0 mm material. Class B provides plus or minus 0.08 mm. Fine blanking typically requires class B or better, as 0.13 mm variation changes optimal die clearance by 10 to 15 percent. For precision components, custom tolerances of plus or minus 0.05 mm are advisable. Thickness variation within a coil should not exceed 0.03 mm for consistent results.

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Flatness and Camber

Maximum flatness deviation should be 5 mm per meter for automatic feeding, with 3 mm preferred for high-speed applications. Camber should not exceed 3 mm per 2 meters. Excessive camber causes misalignment between strip and die, producing asymmetric edge quality and increasing scrap. DC04 and DC06, produced with controlled annealing, typically exhibit superior flatness compared to DC01.

Economic Analysis

Cost Comparison and Material Selection Guide

The cost differential between EN 10130 grades reflects production complexity. DC01 is the least expensive base grade. DC04 commands an 8 to 15 percent premium due to controlled annealing and stricter requirements. DC06 carries a 15 to 25 percent premium, reflecting complex intercritical annealing for ultra-high formability.

For simple flat parts, DC01 provides adequate performance at lowest cost. For general automotive structural components requiring moderate forming, DC04 offers optimal balance of blanking performance, formability, and cost. For complex drawn components where edge quality affects forming success, DC06 is justified despite higher cost because it eliminates edge preparation and reduces scrap. When selecting, evaluate total process cost (material plus blanking plus forming plus scrap), not just per-kilogram price.

Fine blanked oval spacer component made from DC04 cold rolled steel

Selection Decision Matrix

Select DC01 for simple flat parts with no post-blanking forming, where strength is important and edge quality requirements are moderate. Select DC04 for parts requiring flanging, shallow drawing, or bending; for automotive structural components with moderate complexity; and where edge quality must be excellent but ultimate formability is not required. Select DC06 for complex multi-stage drawn components; for parts where the edge undergoes severe deformation; for exposed cosmetic parts requiring best-in-class edge quality; and where scrap reduction justifies the material premium.

For thickness selection, standard fine blanking uses 0.5 to 6.0 mm, with 1.0 to 3.0 mm most common. Thinner materials (below 1.0 mm) require higher-grade material because reduced thickness amplifies edge quality deficiencies. Thicker materials (above 4.0 mm) can use DC01 or DC04 because absolute edge quality requirements are less stringent for heavy-section parts.

DC01 vs DC04 vs DC06 Fine Blanking: Cold Rolled Low Carbon Steel Comparison