At work we have a lot of rail cars come through. The other day the pin that holds the swiveling part of the knuckle broke on one of the cars. I have a piece of it about a foot long. Its between 1-1/4 and 1-1/2 inches in diameter. Thought it could be good stock to make a small hammer out of but im not sure what kind of steel it is, or if it is even worth the effort. Any help would be appriciated. Thanks alot.
~The Mad Rabbit

My first "guess" would be 4140 and it should be great hammer material---try forging a bit down and heating and quenching and checking how hard it gets.

Spark test too to see if it has enough carbon to harden later.

Thanks alot thomas and new jersey man. Ive had a chance to do more research and it seems many producers of the pins use 4140, so u were spot on mr powers. I had put it up to the grinding wheel already but ive never knowingly worked with any carbon steel so i didnt have anything to compair it to. Much obliged.
~The Mad Rabbit

Mad rabbit

If you have worked steel you have worked carbon steel. Steel is an alloy of iron and carbon at the very minimum, it may have other alloying elements but it is still an alloy in its very basic form. We blacksmiths like low carbon for general forging because the carbon is so low it won't appreciably harden. Modern "mild" steel is A-36 which tends to have more carbon in it as well as other trash. They now look at the tensil strength when it comes from the mill and little else.4140 tends to be in the medium carbon range and if memory serves it has cromium and molybdenum as its main alloying elements besides carbon. It will have .4 percent carbon plus or minus .05 percent I think.

Here are some quick links on spark testing there are many

http://en.wikipedia.org/wiki/Spark_testing

http://www.scrapmetaljunkie.com/241/the-spark-test-and-spark-testing-metals-2