metalurgy

[gunnut14]

Not sure if this belongs here so the mods can move it elsewhere if they want!
Back when I was a young pup I grew up in a machine shop (literally) . My Dad owned it and my Mother was book keeper so I grew up in the office until I was old enough to run around underfoot.
My Dad had a way of telling what kind of steel a piece was by grinding it and watching the sparks.
I have been away from the machine shop business for so long I have forgotten what it was. So to me it is lost forever.
I think it was a red spark was like rebar mild steel and the whiter the spark the more it became high carbon steel.
Does anyone know what I am talking about?
Maybe Molly?

I would like to know for my own knowledge. God I hate getting old.



gunnut14

[heathydee]

Some things can be learned from the spark given off as the steel is ground . Higher grades of steels tend to have a starburst spark which is easily compared to a straight line spark . This is not definitive and I would hesitate to classify a steel only by the spark test . However if other simple tests are performed , an educated guess can be made about the material you are dealing with .
I would start with a spark test ,comparing it with a piece of mild steel .
A scratch test using the workpiece against a piece of mild steel with give a comparitive hardness test .
Heating red hot and then quenching is another simple test . Comparing both the hardness and ductility before and after gives further indications of the composition of the steel .
Seeing if the steel can be tempered after quenching will give more knowledge .

[JIMinPHX]

If you only keep 4 or 5 types of steel in the shop, then you can probably identify which of the 4 or 5 types you have in your hand by the spark test. If you grab something from the local scrap yard, or the remnants pile of a local steel yard, then a spark test is not going to be very reliable. If you do a spark test on something like magnesium or titanium, you might be in for a surprise. Those two burn & are quite difficult to extinguish once lit.

[MtGun44]

Finer and lacy sparks come off of harder steels, coarser sparks from softer steels. Not real
accurate, but a rough test.

Bill

[gunnut14]

Thanks Guys,
It is strange where your mind will go when you are tired.
I do not know why I even remembered the spark thing but it has been bugging me for several days.

Maybe it is just getting old and remembering your childhood, I don't know.
It has been happening a lot lately.
I keep trying to remember how he turned (sharpened) a plow disk without removing any metal.
I remember the forge work to make the scoloped edged ones and the case hardening with cyanide.


gunnut14

[old turtle]

How lucky you were to have such a childhood, So many of these skills are being lost. True craftsmen are few and far between these days. People who have these skills are leaving us at a rapid rate.

[Cap'n Morgan]

We have a German metalworking handbook laying around somewhere which must be at least fifty years old. It has a color inlay with different spark examples from various steel types. It works, kinda... but like Jim says, it's best for comparing to a known steel type.

[dragonrider]

A bright white spark will be titanium, yellow sparks will be steels, various straw to red colors can determine what types of steel. there is a list somewhere in the WWW that shows what to look for. A properly worded google search should turn up something.

[dagger dog]

More carbon in the steel gives a thinner white short lived sparks with a starburst at the end when it burns out.

Cast iron or low carbon mild steels give off thick course dull red sparks of long duration, that are long lived some will even stay red once they have fallen to the floor.

This test is relative, to the pieces you test, but you can use it to tell if the steel you're working with will be of sufficient carbon to be able to be hardened.

Try it yourself with a peice of soft mild steel, and an old drill bit , it works better if the samples are the same size,or you can test a corner on a larger sample. Try to use the same amount of pressure when trying it on the grinder.

[oneokie]

I keep trying to remember how he turned (sharpened) a plow disk without
removing any metal. gunnut14

Could have been similar to this:
http://www.google.com/url?sa=t&sourc...A9OJFJgaK9-MzA

[shunka]

It was a common method, my old blacksmith and machining books all had photos. Here you go, from wiki -

http://en.wikipedia.org/wiki/Spark_testing
http://en.wikipedia.org/wiki/File:Spark_testing_1.png

http://en.wikipedia.org/wiki/File:Spark_testing_2.png

[Bret4207]

Thanks Guys,
It is strange where your mind will go when you are tired.
I do not know why I even remembered the spark thing but it has been bugging me for several days.

Maybe it is just getting old and remembering your childhood, I don't know.
It has been happening a lot lately.
I keep trying to remember how he turned (sharpened) a plow disk without removing any metal.
I remember the forge work to make the scoloped edged ones and the case hardening with cyanide.


gunnut14

He probably rolled them. Back in the day before huge equipment and enormous tractors an 8 foot disc might weight 5-600 lbs. You needed sharp edges to penetrate. There was machine made that rolled the disc edge between hardened steel rollers. It sort of swaged the edge on and you wouldn't lose your temper or any metal that way and it was done with the disc on the harrow, no dis assembly required. I've only seen pictures.