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

Standard split lock washers have a left-hand helix, which means you can only use them with bolts that have right-hand threads to prevent clockwise rotation from vibration. When tightened, their uneven split ends bite into unhardened nuts and bolts for a tighter hold than curved or wave washers, but only for applications with clockwise rotation. The washers, nuts, and bolts will be deformed when untightened, so none of them can be reused. Do not use these washers on hardened surfaces.

Stainless steel washers are more corrosion resistant than steel, and nearly as strong. 18-8 stainless steel washers are good for humid, damp, and washdown environments, but will corrode when exposed to salt water and other chlorine solutions. 316 stainless steel washers have the best corrosion resistance. They stand up to wet environments, just like 18-8 stainless steel washers, but unlike 18-8 stainless steel, they resist corrosion caused by salt water, chlorine solutions, and chemicals.

Use zinc-plated and yellow zinc-plated steel washers in mostly dry environments. The zinc plating offers temporary rust protection, but once it wears away the steel will rust. All of these washers are stronger and more wear resistant than stainless steel.

Steel washers are stronger and more wear resistant than zinc-plated steel and stainless steel. Use them in dry environments because they will rust in wet and corrosive environments.

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