Believe it or not, car and truck leaf springs make great knife blades!
These discarded automotive parts are a very good source of knife steel as they are usually made from 5160 carbon steel. Many highly regarded custom knife makers use this steel source to great effect for their highly desirable custom creations.
A young barefoot bladesmith we discovered working in Vietnam uses this interesting source to make some very funky and fun blades for us. They are rough and ready basic blades that will make a great project knife for budding sharpeners or chefs and enthusiasts looking for something to play with. The actual grinds of these blades are rather special, they are sharp and they hold an edge beautifully.