No. A diode cuts half the waveform so 50% power, but a US 110V element is one quarter of the (hot) resistance of an equivalent rest of world 220V element (for double the current at half the voltage to get the same power), and at 220V would be overrun by a factor of four, so even with the diode would still be overrun by a factor of two. Also that would put DC across the magnastat switch which is likely to shorten its life