The C231M has a max. rep. off-state voltage of 600 volts, a max.
static on-state current of 25 amps at 70 °C, a max gate firing
gate current of 9 mA, a max. gate voltage of 1,5 volts, a max.
holding current of 50 mA, a max off-state current of 1 mA at
100 °C, . . . .
Now that you've got the major characteristics, I think you can
find a suitable replacement for it.