Yesterday I plasma cut some notches in 3 x 1/2 x 4 cold rolled. The pieces were hot so I dropped them in a pail of cold water.
Today I tried to plunge a new 1" diam. end mill through the material to clean up the end of one notch....... no luck!!!!!..... That material really is hard. I didn't think one could "heat treat" cold rolled but, apparently one can........ that must explain why the slag on the bottom was difficult to remove.
I'll try cutting again w/o the cold water and see if the material is machinable...... I would guess that it will be.
Now for the question..... Is mig welding heat treated any different than on mild steel, in so far as the strength of the weld is concerned???? I would guess that the weld doesn't penetrate the base material very well and therefore, one would use a hotter setting..... right????