Re: What is going on with the phenomena of spark patterns of steel grinding?

Roger,
Spark testing is an elementry method for identifying steel alloys. 
Emission spectrometers and X-Ray emmission analyzers, some being portable 
for field work, has replaced spark testing.

But anyhow, spark testing is an inexpensive method to identify steel 
alloys within a range of suspected types. Spark streams emmitted from 
holding a steel sample against a grinding wheel will produce spark 
patterns characteristic of specific alloys. Some of the characteristics 
are the color of the spark, length of the spark stream, intensity, single 
or multiple bursts and lots of experience.

I cannot find a cross-reference of spark patterns vs. steel type probably 
because there are hundreds of steel alloys to catagorize involving lots of 
time and research.
 
The way to set up a test is to have available specimens of known alloys 
involved in a search that can be compared with the unknown sample. This is 
also required for analyzers which are capable of storing spectographic and 
X-Ray data. 


Ref: http://www.escribe.com/science/keelynet/m8562.html