I may be wrong here (I know power transformers, but not the pecularities of welding transformers), read the plate on the welding transformer, it will probably state 50-60HZ.
If the welding transformer is made for 50-60HZ, this is not a good Idea, a power transformer will be made for the frequency of the supply. It will probably burn under heavy load if you feed it 3* the nominal frequency.

Welding transformers used in my machines are not bought from outside but are made in house. Our transformer designer can design transformers for 150Hz or any desired frequency. The main advantage in using a higher frequency transformer is my number of cycles for welding will increase and I can use PID control for getting desired RMS welding current.

Regards,
Prahlad Purohut