Q235 black annealed cold rolled full hard coil is a steel coil product made of Q235 carbon structural steel as raw material, which is kept in full hard state (not annealed and softened) after cold rolling.
Q235 Black Annealed Cold Rolled Coil Full Hard Performance Index:
|
Item |
Parameter range |
Test Standards |
|
Tensile strength (Rm) |
550-700 MPa |
GB/T 228.1 |
|
Yield strength (Rp0.2) |
450-600 MPa |
GB/T 228.1 |
|
Elongation (A50mm) |
5%-12% |
GB/T 228.1 |
|
Hardness |
HRB 80-95 |
GB/T 230.1 |
|
Thickness tolerance |
±0.05mm(≤2mm) |
GB/T 708-2019 |
Full hard Cold Rolled Steel Coils Black Annealed Features:
Material standard: Meets GB/T 700-2006 Q235B requirements
Status characteristics: No annealing after cold rolling, retains work hardening characteristics
Surface treatment: Black oxide film (not pickled, no coating)
Mechanical properties: High strength, low plasticity
Black Annealed CRFH process features:
Cold rolling compression ratio: 60%-80% (determines the final hardness)
Surface roughness: Ra 1.2-2.5μm
Metallurgical structure: ferrite + pearlite (cold deformation structure)
Residual stress: needs to be controlled through the flattening process
Compared with conventional Q235
|
Characteristics |
Fully hard Q235 |
Annealed Q235 |
|
Tensile strength |
550-700 MPa |
370-500 MPa |
|
Yield strength |
450-600 MPa |
235-400 MPa |
|
Elongation |
5%-12% |
22%-26% |
|
Applicable process |
Shearing/punching/welding |
Deep drawing/bending |
Q235 Full hard CRBA Coil processing precautions
Pressing:
Suitable for simple punching only (aperture ≥ plate thickness)
Recommended die clearance: 8%-10% plate thickness
Requires high hardness die steel such as SKD11
Welding process:
Recommended gas shielded welding (MAG)
Preheating temperature: 100-150℃ (when plate thickness > 6mm)
Stress relief annealing is required after welding (such as 300℃×1h)
Surface treatment:
Sandblasting is required before phosphating (Sa2.5 grade)
The recommended electrostatic spraying film thickness is 60-80μm
Q235Black Annealed Full hard cold rolled steel strip Applications
Building structures: curtain wall keels, earthquake-resistant brackets
Machinery manufacturing: conveyor rails, equipment guard plates
Auto parts: reinforced linings, fixed brackets
Hardware products: high-strength fastener substrates
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