Originally Posted by
squirtdad
Crank arms are supposed to be torqued at around 35 to 40 nm, which is not insubstantial, my guess is that is why you don't find aluminum crank bolts
There were aluminum crank bolts, as smd4 noted. The general recommendation was to use steel bolts to apply full torque and then substitute the aluminum bolts as replacement. More than one aluminum bolt was broken by not following this procedure.