I'm doin research for materials engineering at ubc and decided to throw a couple of sprocket teeth in the scanning electron microscope and run some tests to see how good these things are. The sprocket was a stock steel 16 tooth front from a 97 gsxr with 27 k on it.
Metalography shows different steel structures on the edge than the center. From these compositions and metalography images my best guess is that they use 4160 steel, that been thoughly heat treated. This is a tough metal. Although not the best steel, it is easily heat treatable and relatively cheap.
Vickers micro hardness = 550 at edge, 500 at center, (diamond, hardest material known is about 700)
Hardness can be correlated to wear resistance and perhaps to increase this one could carburize/nitride the surface. Maybe i'll do this with a rear sprocket layin around.
Does anyone have a used aftermarket sprocket they are willing to donate that i can use to compare agaisnt stock? Would be intresting to see the quality difference.
Also, i think aluminium sprocket are crap if your running any serious amounts of torque. Aluminium has the worst wear rate of any metal. Anodizeing helps this but it's only a thin layer, i'm not sure if it even covers the teeth.
Did a whole write up on this shit, so any questions let me know.