Stainless Bolts on Steel Edges: Galvanic Corrosion and Why the Mix Matters

Scenario: a supplier suggests stainless bolts for a steel cutting edge to avoid rust. Direct answer: the general galvanic principle is that a small fastener of the more noble metal in a much larger part of the less noble metal normally causes little galvanic trouble, whereas the reverse can be a problem. That does not make stainless bolts right for an edge, because strength class, wear and crevices also matter. I read a Euro Inox guide on 24 October 2026; it does not discuss plows.

What the guide says

The guide’s argument is about area ratios rather than about stainless being better, and that distinction changes the answer.

• Galvanic corrosion can occur when two different metals touch in the presence of an electrolyte such as salt water.
• It is likely to occur if the anode (the less noble metal) is small and the cathode (the more noble metal) is large.
• Stainless fasteners on much larger galvanised steel components “do not normally cause corrosion”, and the guide says that in material combinations, fasteners should be made of the more noble material, so that the cathodic surface is small.
• Designs with small anodes and relatively large cathodes should generally be avoided.
• Design factors matter: crevices, stagnant water and dirt that keep surfaces damp increase the risk, while good drainage and drying reduce it.

What it suggests for a steel edge

The guidance points at the area ratio, which is the one variable a buyer can actually see.

1. A stainless bolt in a large steel edge is the “small cathode, large anode” arrangement, which the guide treats as the safer one in principle.
2. The reverse, a plain steel bolt in a large stainless part, is the arrangement to avoid.
3. Wet, salty crevices around bolt heads and under nuts still deserve attention.

What it does not say

The guide describes general practice, not plow edges in salt.

• It does not address plow edges, hardened steel or carbide, so any statement about your edge is an inference.
• It says nothing about bolt strength. A stainless bolt must still meet the strength class your edge needs; ask the maker.
• It does not cover wear, thread damage or cost.

Questions for your supplier

Stainless fasteners on a steel edge are a galvanic pair, and the answer depends on the environment as much as the grade. Three questions settle most of it.

1. What strength class and grade is the stainless bolt, and is it suitable for the load? Corrosion resistance and strength do not move together across stainless grades.
2. Has it been used on edges like mine, and what happened? Ask for the conditions: salt exposure, wash-down routine and service life.
3. Do you recommend any coating or lubricant on the threads? A barrier compound slows the couple but changes the torque figure, so ask for both answers together.

Boundary: The guide does not mention plows or bolt strength; the application to edges is an inference, so confirm strength class and suitability with the fastener maker.