1.What should you check first upon arrival? What are the key points for inspecting the packaging and appearance?
First, check if the outer packaging is intact.
Inspect the rust-proof paper, plastic film, iron corner protectors, and steel straps for damage, moisture, rust, or displacement. If the packaging is torn or shows signs of water ingress, be wary of rust on the internal steel coils.
Check the ends of the steel coils for impact deformation, whether the corner protectors are crushed, and whether the steel straps are broken or loose. If wooden crates or pallets are used, check for cracks in the crates and mold on the pallets.
Record the packaging condition and take photos as evidence for future claims.
2. How to inspect the surface quality of cold-rolled coils? What are the common defects?
After unpacking, focus on inspecting the inner and outer surfaces and edges of the steel coil.
Rust: Observe for yellow spots, red rust, or black spots, paying particular attention to interlayer gaps, edges, and areas where the packaging is damaged.
Scratches and Indentations: Check the surface for longitudinal or transverse scratches, roller marks, and indentations.
Edge Defects: Check for cracked edges, serrated edges, rolled edges, or burrs.
Oil Stains and Foreign Object Indentation: Confirm that the surface is free of residual oil stains, emulsion spots, or foreign object indentations.
Flatness: Visually inspect or use a ruler to check for edge waviness, center waviness, or warping.
For critical applications (such as automotive steel sheets), it is recommended to use a portable surface roughness tester or oil film thickness gauge to randomly check key indicators.
3. How to inspect the dimensional accuracy of cold-rolled coils? What parameters need to be measured?
The following dimensional parameters need to be measured and verified against the purchase contract or warranty certificate:
Thickness: Use a micrometer or ultrasonic thickness gauge to measure at least 25mm from the edge. Take at least three sections from the beginning, middle, and end of each coil, measuring multiple points at each section.
Width: Measure along the coil width using a steel tape measure, ensuring the width is consistent at both ends and in the middle.
Inner Diameter/Outer Diameter: Confirm that the inner diameter meets the requirements of the uncoiling equipment (usually 508mm or 610mm), and that the outer diameter does not exceed the lifting limit.
Coil Weight: If possible, verify by weighing, or calculate the total weight from the unit weight.
Permissible deviations should refer to the relevant standards (such as GB/T 708, ASTM A568, etc.). Deviations exceeding the tolerance range are considered unacceptable.
4. How are mechanical properties and chemical composition inspected? Is sampling and re-inspection required?
Accompanying Documents: During acceptance, the quality assurance certificate (material certificate) must be verified to confirm the grade, heat number, coil number, mechanical properties (yield strength, tensile strength, elongation), chemical composition (C, Si, Mn, P, S, etc.), and processing condition (annealing method, flatness).
Appearance and Document Consistency: Check whether the label information on the steel coil is consistent with the quality assurance certificate.
Is Re-inspection Required: For critical applications or in cases of quality disputes, samples can be taken after uncoiling according to standards (such as GB/T 228.1) and sent to a third-party laboratory for testing. Sampling locations are usually on the outer or inner coil, avoiding obvious defects.
Note: The performance of cold-rolled coils may be related to the heat treatment process (such as continuous annealing or bell-type annealing). If performance discrepancies are suspected, re-inspection should be completed before processing.
5. What to do if non-conformities are found during acceptance? What are the common reasons for rejection?
If the following situations are found, unloading should be stopped immediately, and photos and videos should be taken as evidence. The supplier and the transporter should be notified simultaneously:
Severe corrosion: More than slight yellowing, red rust or pitting appears.
Severe deformation: Core misalignment, collapse, oval end face.
Severe packaging damage resulting in visible contamination or water damage.
Severe dimensional deviation: Thickness or width exceeds standard tolerance range.
Performance non-compliance: Missing warranty certificate, incorrect grade, or failure to meet mechanical performance standards upon re-inspection.
Handling procedure:
Fill out the acceptance record form, recording the location, extent, and measurement data of the defects in detail.
Retain samples or seal part of the goods, and apply for notarized inspection if necessary.
Request a return, exchange, downgrade acceptance, or claim according to the contract terms.
For minor defects (such as a small amount of surface oil stains, minor burrs on the edges), a concession can be negotiated with the supplier, deducting the corresponding price difference.