We ALWAYS specify both the raw material and any secondary operations such as post machining heat treatment or plating. For most raw materials we require chemistry and depending on the application may require hardness, tensile strength, grain size or even magnetic properties. For a lot of critical bar stock we also require ultrasonic crack inspection. Heat treatment or plating specifications always have pass/fail requirements for hardness, case depth, plating thickness, etc. There may well be other tests for toughness or adhesion, etc.
Our drawing format has individual blocks for the raw material specification, the heat treatment specification and the finish specification (paint, plating, etc.). If you can't put it in one line in the block then either reference a note or if you can't write it in a couple of lines of a note then write a detailed specification and reference it in the drawing format.
I know some people say you should only specify the final product but after we spend 4 years qualifying a design that was made from bar stock the last thing on earth we want is some supplier to start using powder metal blanks or vice versa. We actually do most machining in house as well as heat treatment but sometimes we get too busy and have to outsource. It's critical that parts we buy outside have the same provenance as parts we make.
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