So I recently acquired two 3" thick, 9" in diameter cylindrical hunks of steel and I need a second opinion. I want to turn at least one of them into a striking anvil. In the meantime I would like to know if this is either mild steel or medium carbon, or just plain malleable iron. I just want to be sure before I make an attempt to heat this steel and harden and temper it (Seems to dent under direct cross pein hammer swipes). I have attached several photos.

 

Thanks.

 

EDIT: I was also using a worn out flap disk to create the spark.

Try this in a google search:  spark test site:iforgeiron.com

I feel a spark test is a poor shop test. There are a lot of folks that are really good at it but none of them were when they first started it. There are always folks on here tell new folks in here, "just spark test it" That supposes a lot of skills thatg may not be there and specific needed skills.

One of the main things needed for this procedure is a lot of samples of known materials to compare to. I do believe someone handy in  ashop can get good  at it, and also belive that if a few folks do this as a group thing it will go faster. I am not a fan of seeing in text or pics that this steel is this as the spark testing looks like this. How it appears to me may not be how you see it.

I  prefer testing for each specific piece I want to know about. And for wot you are loooking for I would slice off a piece and run it through heat treat testing and see how it does. See if it will  harden,,then draw that back with several step program until you can tell if it is going to work for you.

It doesn't matter anyway. I just re-read Brian's striking anvil thread and he uses mild steel incase of misses with heavy sledges, so I'm not going to harden it. Thanks anyway guys.

It doesn't matter anyway. I just re-read Brian's striking anvil thread and he uses mild steel incase of misses with heavy sledges, so I'm not going to harden it. Thanks anyway guys.

 

I was going to suggest the above but you got it. 

 

Perhaps now it is more about how you will get tooling in a hardy hole and how you will mount it on legs for solid support and striking...  height....

I agree that reading the sparks takes practice and that one should compare an unknown to a known. A hand held side grinder with a small wheel may have too much rpm to get a good reading, especially if one presses too hard. I find that a bench grinder works best with a light touch on the wheel with the sample piece. Pressing too hard causes a bigger shower which is difficult to define. Don't let the sparks bounce off the tool rest. The tester should look at the shower and individual carrier lines about halfway out from the wheel to the end of the shower. Sometimes, there are breaks and dashes at the end of  the lines. which are telling.

 

The spark test works best with plain carbon steels, wrought iron, and gray cast iron. It becomes increasingly difficult to read when one gets into alloy steels.

1045

 

Cross check with a comp on a piece of mild steel and known 1045 from heavy shaft or ebay.

Also just judging from the spark int epic I would tend to think this is a lower medium carbon steel and closer to plain steel than alloys. However 4140 puts out a similar spark but with more burst in my opinion. I have gotten differing degrees of result based on pressure like
Frank says so,  what I am am saying is only a guess. Like said before if you want to be sure then cut off a piece and harden it and test the result.

I'm not sure of the availability but if you can find a copy of "The Art of Spark Testing" by Edsel E. Bishop and published in 1954 by Wyckoff Steel Company grab it, even if you have to mortage the wife.  It comes with a red/green celophane viewer in a cardboard frame that you hold up to your eyes for viewing the 3D colored drawings contained in the book (like the old 3D movies in theatres)  and it is the most thorough treatment of spark testing I've seen.  There are many factors affecting the spark and as Frank Turley pointed out, it is important how you produce a spark for proper reading.  Things like length and angle of the spark stream, type and frequency of bursts, distance at which the bursts occur from the wheel, color of the stream, the clarity of the carrier stream all give hints as to the parent material.  Some trace elements make a stream lighter and some darker.  In addition to a great explanation of spark testing and profuse examples, the book contains charts for nearly 100 varieties of steel, iron, and alloys with the characteristics particular to each in a spark test.  I was very fortunate to obtain a copy many years ago from a salesman for Bethlehem Steel when he retired and gave me his library.  Maybe somebody will reprint the book if there is enough demand. 

 

Neal

I'm not sure of the availability but if you can find a copy of "The Art of Spark Testing" by Edsel E. Bishop and published in 1954 by Wyckoff Steel Company grab it, even if you have to mortage the wife.  It comes with a red/green celophane viewer in a cardboard frame that you hold up to your eyes for viewing the 3D colored drawings contained in the book (like the old 3D movies in theatres)  and it is the most thorough treatment of spark testing I've seen.  There are many factors affecting the spark and as Frank Turley pointed out, it is important how you produce a spark for proper reading.  Things like length and angle of the spark stream, type and frequency of bursts, distance at which the bursts occur from the wheel, color of the stream, the clarity of the carrier stream all give hints as to the parent material.  Some trace elements make a stream lighter and some darker.  In addition to a great explanation of spark testing and profuse examples, the book contains charts for nearly 100 varieties of steel, iron, and alloys with the characteristics particular to each in a spark test.  I was very fortunate to obtain a copy many years ago from a salesman for Bethlehem Steel when he retired and gave me his library.  Maybe somebody will reprint the book if there is enough demand. 
 
Neal

Just found a copy with glasses and all and bought it. Thanks!