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Zinc Plating is known for its ability to prevent most corrosion, and it is done by just dipping a metal in hot pool of zinc and letting it cooldown. Meanwhile, stainless steel, an alloy that is capable of resisting corrosion.

Zinc Plating Advantages:

  • Cheap

Stainless Steel Advantages:

  • Is not coating (hence, scratching will not expose for corrosion)
  • Hardnesss of Material ($UTS_{Stainless} \approx 860 \frac {N}{mm^2}$) comparatively to Mild Steel ($UTS_{Mild Steel} \approx 470 \frac {N}{mm^2}$)

Other than what is said, in what circumstance would you use stainless steel over galvanized steel?

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  • $\begingroup$ Much zinc coating is electroplated . Also , zinc rich primer ( paint) gives about the same protection. The main advantage of zinc is that it is cheap ( compared to SS ). $\endgroup$ – blacksmith37 Nov 13 '18 at 15:39
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    $\begingroup$ A little bit of nitpicking on terminology, "zinc plating" is likely to be interpreted as electroplating; which isn't quite the same as hot-dip galvanizing. They accomplish a similar task; but electroplating is generally less expensive and less protective; as it's a thinner layer of protection. $\endgroup$ – JMac Nov 13 '18 at 20:36
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Stainless steel can be used up to temperatures of about 1000C. The corrosion resistance of zinc plating decreases rapidly above 100C, and embrittlement can occur above 500C.

Zinc plating has lower resistance to chemical corrosion from acids and alkalis than stainless steel.

Aside from mechanical damage caused by scratching, the rate of corrosion may not be uniform over the whole structure, leading to local failures of the protective layer.

Zinc plating will fail if it is in contact with some common construction materials, including copper, brass, chrome plated materials, unplated iron and steel, bitumen, some species of timber (including oak, cedar, and some fir species) etc.

Fabricating a structure from plated raw materials may damage the plating layer and reduce the corrosion resistance (e.g. assembly using bolts and screws, bending plated sheet metal, etc).

Welding plated steel requires special precautions to make good quality joints and to protect the operator from fumes containing zinc compounds.

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