As you tighten a bolt, these metric washers flatten to add tension to the threaded joint and prevent loosening from small amounts of vibration. They meet a DIN or ASME standard for split lock washer dimensions.

Curved and wave split lock washers can be used with fasteners that have right- or left-hand threads to prevent clockwise and counterclockwise rotation. These washers are reusable—they retain their shape when untightened and will not damage fasteners. Wave washers touch fasteners at more points, so they grip tighter than curved washers. Their shape also compensates for uneven surfaces and tolerance variations.

Stainless steel washers resist corrosion better than steel and are nearly as strong. 18-8 stainless steel washers withstand humid, damp, and washdown environments but will corrode when exposed to salt water and other chlorine solutions. Stronger and more durable than stainless steel, zinc-plated and yellow zinc-plated steel washers withstand wet environments. However, they will corrode in salt water and chlorine solutions. The zinc plating temporarily protects against rust, but once it wears off, the steel will rust.

Steel washers are stronger and resist wear better than zinc-plated steel and stainless steel washers. Use them in dry environments. Black-oxide steel washers have a black residue that forms from being heat treated; the color will wear away over time.

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