Fastener Corrosion and Stainless Steel
In short: Corrosion weakens fasteners and makes them hard to remove. Choosing the right material and coating, avoiding contact between dissimilar metals and handling stainless steel correctly prevents most problems.
See: HardwareTalk to our technical team
Corrosion is one of the most common reasons fasteners fail. It weakens the fastener, damages the parts around it and makes removal difficult.
How fasteners corrode
Moisture, salt, chemicals and pollution cause steel to rust. Coastal, mining, chemical and outdoor sites are the most demanding.
Prevention: choose the right material (stainless steel, coated or galvanised steel), keep coatings intact, avoid trapping water, and inspect regularly.
Galvanic corrosion
When two different metals touch in the presence of moisture, the less noble metal corrodes faster. A common example is a zinc-plated steel fastener in an aluminium or stainless steel assembly.
Prevention:
- Use fasteners of the same or a compatible metal.
- Insulate dissimilar metals with washers, sleeves or coatings.
- Keep the joint dry and sealed where possible.
Getting the best from stainless steel fasteners
Stainless steel resists corrosion well, but it is not indestructible.
- Choose the right grade: A4 (316) for coastal and chemical environments; A2 (304) for general use.
- Prevent galling: tighten slowly and use anti-seize. See Fastener Threads Explained.
- Avoid contamination: carbon steel tools and debris can cause rust spots.
- Remember that stainless steel is generally lower in strength than high-tensile steel.
Recycling fasteners
Steel, stainless steel and aluminium fasteners are all recyclable. Separating them by material when stripping equipment improves their scrap value and reduces waste.
Avlock’s hardware range includes coated and corrosion-resistant fasteners for industrial use. See also Choosing Fastener Material, Size and Strength.