Spring Lock Washers are similar to Flat Washers, with a small twist. The major difference between Spring Lock Washer and a Flat Washer is that the Spring Lock Washer is separated at one point, which disconnects the washer.
The Flat Washers will also have a larger outer diameter comparing to the Spring Lock Washer will have a small outer diameter, because force distribution is not its main concern. The Spring Lock Washer will become like a Flat Washer once it is fastened and flattened.
However, the difference is when the fastener starts to loosen up, the spring like action of the Spring Lock Washer will increase friction and stops the fastener from rotating.
The Spring Lock Washers is also used as a component in some fasteners, such as the SEMS Screw.
The common material for Spring Lock Washer is carbon steel with a zinc or yellow zinc coating. However, they are also made in stainless steel and brass.