Definetly check the speed settings on the saw. If you're regularly losing blades before their time, the most likely culprit is either too low on the blade speed or too high on the cutting pressure (or both). Another possibility lies in the vise jaws. If the jaws aren't gripping properly, even a slight slippage of the material can torque the blade enough to cause it to bind and snap.
Odd thought- Is your operator cutting heat-treated material? That can be a bit tricky, as well, depending on how it's treated. I had a problem with some cast steel parts I was cutting down to save the machinists some time. Turns out the parts hadn't been treated to spec- instead of hardened all the way through, they were only hardened to about a half-inch depth.