Three Core Stainless Steel Surface Treatments: Trends & Applications

Stainless steel is widely used in construction, medical, and food sectors for its corrosion resistance and aesthetics, but processing causes oxide scale or scratches. Its surface treatment relies on three core technologies, with green and intelligent development emerging.

I. Natural Color Whitening
It removes black oxide scale (e.g., NiCr₂O₄) and boosts corrosion resistance. Sandblasting uses compressed air to spray glass beads, ideal for large parts like chemical tanks—one petrochemical project saw 3x better epoxy adhesion. The chemical method uses eco-friendly pastes to form a Cr₂O₃ film, suiting precision tools (304 instruments endured over 1,000 hours of salt spray).

II. Mirror-Like Brightening
It creates reflection via polishing, graded by finish (8K: Ra≤0.1μm, ≥85% reflectivity; 10K: Ra≤0.05μm). Mechanical polishing uses abrasive belts/wheels—an elevator trim project hit 600GU gloss. Electrolytic polishing (stainless steel as anode) treats complex parts evenly, forming a 10-50nm film that lifts corrosion resistance by 2-3x; medical endoscopes saw 90% less bacterial adhesion.

III. Surface Coloring
Colored oxide films enhance decor, wear resistance (2-3x), and corrosion resistance (3-5x longer salt spray). Chemical coloring (e.g., INCO method) controls ΔE≤1.5 (subway bronze columns lasted 500 hours). Electrochemical coloring adjusts voltage (20V=gold, 25V=blue) for phone frames (HV600 hardness). PVD (vacuum sputtering) offers 20+ colors—high-end watches had HV2000 hardness.

Traditional pickling is replaced by laser cleaning (120 tons less waste/year). AI inspects polishing quality; "sandblasting+PVD" is used in home appliances. Future treatments will focus on efficiency, eco-friendliness, and multi-functionality.