On Wed, 12 Jan 2005 17:25:23 -0500, Paul J Shelc
wrote:

I ran across some of this in a scrap pile. What is maraged steel m300?
What would be a good use for it. I have a piece about 1" dia x 48"
long. Can it be heat treated?

It has been heat treated.
Heat treating it again would make it something else.

Maraged Steel - A high-nickel-content, low-carbon steel that is heated
to 1500F (822C), air-cooled, and then aged at 900F (486C). Maraged
steel is generally considered a superalloy.