Common refurbishment methods for overheated H13 parts include re-engraving serial numbers, partial polishing to cover damage, recoating after welding repairs, and using ordinary steel to impersonate parts and forging material certificates. These operations aim to disguise them as usable parts or high-value recyclable parts, posing serious safety hazards.
1. Re-engraving Part Serial Numbers and Forging Marks
Refurbishers grind away the original serial number or stamp and re-engrave a false serial number, or even copy the serial number of other genuine parts; some use lasers to re-engrave QR codes or barcodes, forging traceability information and misleading recycling or reuse decisions.
Risk Points: Misaligned serial numbers, inconsistent fonts, and burrs on the edges are typical signs of refurbishment.
2. Partial Polishing and Selective Repair
Partially polishing areas with obvious overheating (such as nozzle tips and manifold connections) to cover oxidation, blistering, or "prickly heat" bulges; only surface defects are treated, internal grain boundary oxidation and microcracks are not eliminated, and sudden fractures may still occur during service.
Identification Techniques: The surface gloss differs between old and new, with obvious transition areas and non-uniform wear.
3. Weld Repair and Coating Disguise: Cracks or chips are repaired using ordinary welding materials, then the weld marks are covered by grinding; the welded area shows abnormal composition (e.g., Ni or Fe enrichment), which XRF testing can detect as incompatible with the H13 matrix; Safety Warning: H13 steel cannot be repaired by welding. Any welding will introduce thermal stress and accelerate failure.
4. Substituting Inferior Goods and Forging Material Certificates: Ordinary carbon steel or low-alloy steel parts are passed off as H13, with fake Certificates of Assurance (COA) or Bills of Materials (BOM); during recycling, they are falsely labeled "PM-H13" to obtain higher prices, when the actual composition is far from meeting the standards.
