Heat treat/ cold rolled

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????

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Plasma cut edges are alwasy nasty. Quenching in water would have little or no effect.. By the time you hang up your torch and grab the piece to throw it in water the edges have long ago lost their red heat. The hard edge is created by the heat sink effect of the metal adjacent to the plasma kerf. I suspect the carbon content on the edge is also different than the parent metal. Welding on mild steel and high carbon steel with MIG would not be different to the person welding. The alloying of the extra carbon in the weld metal is what changes things. The rate that the steel cools through critical temp and the hydrogen trapped in the weld bead are the items of concern. Randy

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Randy Zimmerman

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