How to tell if found "iron" is wrought iron?

[rich pierce]

Sometimes it's easy to tell if a badly rusted piece of iron is wrought iron because the grain which is easily seen. I imagine that's coarse quality stuff with lots of silica still in it.

How can one determine if a piece in nice shape is wrought iron or mild steel?  I found a nice piece of old iron in a creekbed.   It makes a "bonk" sound instead of ringing when I hold it up and hit it with a hammer, so it's definitely very mild.  Can one tell by sparks off a grinder if it's wrought or mild steel?  Or by grinding a section bright across 2 planes (showing the surface and the ends)?  Or do I have to try to forge weld it to find out?

[Randy Hedden]

Rich,

One way to find out if it is wrought iron would be to spark test it with a grinding wheel or compressed air.  During my apprenticeship I did a 3 month stint as a spark tester in our steel warehouses. Just Google "spark testing wrought iron" and you can get a quick education about spark testing.  The compressed air method is more accurate, but you should do fine with the grinding method.  You could probably Google "spark testing steel video" and see some actual spark testing.

Spark testing seems to be rarely used these days.  I had not spark tested anything for 30 years and then the company was trying to find someone with knowledge of spark testing to test some castings. They could only locate two of us who had spark tested in the past and wanted one of us to fly to Bombay, India. I let the other guy go on the trip. This lucky got to Bombay and then had to travel almost 200 miles on a bus to get to the foundry.  You know, one of those buses with the chicken and pigs inside and people riding on top the bus.

Randy Hedden

[Acer Saccharum]

I will look up spark testing in some of my machinery's handboks. I imagine dull red sparks for iron, little or no starburst sparks. With higher carbon steel, brighter sparks, with more little 'explosions' or starbursts at the end of the spark trail?


http://shopswarf.orconhosting.net.nz/spark.html

 WIki:    Wrought iron sparks flow out in straight lines. The tails of the sparks widen out near the end, similar to a leaf.  http://en.wikipedia.org/wiki/Spark_testing

If you want to read about life in India, read "Shantaram". Fascinating, frightening, beautiful. http://www.amazon.com/Shantaram-Novel-Gregory-David-Roberts/dp/0312330529#reader

[jerrywh]

It is extreemly hard to tell the difference between the sparks of wrought iron and something like 1117 or 12L14  or even 1018.   If you take a peice of wrought iron and break it by bending it back and forth , you can see the grain in the break.  You can also see the grain if you put acid on it for a while.

[jmforge]

If it shatters, it's cast iron.   Most folks in the knife biz looking for wrought want the "dirty" stuff with all of those silicate inclusions because it looks very cool when you etch it, and they warn you not to forge it down too much or you will break up and distribute the gunk and lose your pattern kind of like forging down a piece of nickel-iron meteorite..  With that said,  I wouldn't want to use any of that stuff anywhere on a gun!!!

[flintriflesmith]

Just to follow up on what Jerry said, on my web site the is a picture of a broken bar of wrought iron that shows the grain he mentioned.

http://www.flintriflesmith.com/Writing&Research/WebArticles/iron_and_steel.htm

Gary

[rich pierce]

That'll do it.  I'll grind some then cut partway through the bar and break it the rest of the way.

[jmforge]

Just to follow up on what Jerry said, on my web site the is a picture of a broken bar of wrought iron that shows the grain he mentioned.

http://www.flintriflesmith.com/Writing&Research/WebArticles/iron_and_steel.htm

Gary

Good pictures, Gary.  The way that I was going to describe it was that a bar of wrought kind of breaks like you would expect a waterlogged popsicle stick to break.

[JCKelly]

Here are two parts of the wrought iron anchor from the Pewabic, which sunk in 1865. Currently on display outside the Jesse Besser Museum, exposed to the nice weather, in Alpena, Michigan.
The anchor 

And a band around the anchor shaft (terminology, Navy guys?)


If you found your iron in a creek bed, I'd expect it to show nice lines vaguely like on this old wrought iron.

Do you have a good photo, perhaps with low angle lighting to bring out the surface texture?

[rich pierce]

The stuff I found in the creek was not wrought, it was medium carbon steel.  But my old horseshoe, where I can clearly see the grain, sure sparks just like the illustration in the websites you guys provided.  Long straight sparks with some blobs at the end.