There should be a sticker somewhere on the frame to indicate that. I had a 1999 M50 which was a mix of chromoly and hi-tensile steel. Bikepedia is very helpful for these things: http://www.bikepedia.com/quickbike/B...=M50&Type=bike

You can do a Google search for any bike (made after ~1991) like this. I typed in "1999 Raleigh M50 bikepedia"