Not a good idea. The 12 V relay has contacts rated at 12V20Amps DC.
To switch AC at mains potential there is not enough clearance when the contacts are open.
Generally it is harder to break DC current, so 12 V dc rated contacts will break 24 V ac allright at 20 Amps.
Bear in mind that the peak value of 230V mains is 325 Volts !!
Other matter is that the relay is not insulated to the mains voltage level, and a possible flashover might occur between your 12V control circuit and the 110 or 230 V mains.
There are plenty of cheap 12 or 24 Volt control relays about which can safely switch 230 V at 8 Amps or higher.