Identifying Scrap Metals with Spark Testing

Spark testing your metals is in my opinion, usually the easiest way to identify your metal types.

This is a simple process, generally you'd take an angle grinder to your metal, and observe the sparks (if any), to determine the type, since all metals spark differently.

Here's a piece of an article I found at Wikipedia with some simple guidelines for a few of the common types of metals, including 300, 310, and 400 series stainless steels. Link to the full page below.

Wrought iron
Wrought iron sparks flow out in straight lines. The tails of the sparks widen out near the end, similar to a leaf.

Mild steel
Mild steel sparks are similar to wrought iron's, except they will have tiny forks and their lengths will vary more. The sparks will be white in color.

Medium-carbon steel
This steel has more forking than mild steel and a wide variety of spark lengths, with more near the grinding wheel.

High-carbon steel
High-carbon steel has a bushy spark pattern (lots of forking) that starts at the grinding wheel. The sparks are not as bright as the medium-carbon steel ones.

Manganese steel
Manganese steel has medium length sparks that fork twice before ending^.

High-speed steel
High-speed steel has a faint red spark that sparks at the tip.

300-series stainless steel
These sparks are not so dense as the carbon steel sparks, do not fork, and are orange to straw in color.

310-series stainless steel
These sparks are much shorter and thinner than the 300-series sparks. They are red to orange in color and do not fork.

400-series stainless steel
400-series sparks are similar to 300-series sparks, but are slightly longer and have forks at the ends of the sparks.

Cast iron
Cast iron has very short sparks that begin at the grinding wheel.

Nickel and cobalt high-temperature alloys
These sparks are thin and very short, they are dark-red in color, and do not fork.

Cemented carbide
Cemented carbide has sparks under 3 inches, which are dark-red in color and do not fork.

Titanium
Although titanium is a non-ferrous metal, it gives off a great deal of sparks. These sparks are easily distinguishable from ferrous metals, as they are a very brilliant, blinding, white color.

Spark testing - Wikipedia, the free encyclopedia

Additional spark testing information

ALUMINUM
Generally does not throw sparks.

I know this depends on the yard but how exactly would chrome plated al be graded ? Breakage maybe ?