Hi __________(sircantaloupe) and Folks,
There are a dozen or so photos of portions of the rail construction at this sight,
http://www.azcentral.com/commphotos/azcentral/4528/1/14. (There were several breaks that developed and needed repair.) I didn't catch sight of any of those spring looking clips though. Sure seems like it would be fun to find out what they are. The reason I asked if you have access to a fair amount of them is, that if you wanted to, you could easily get an alloy analysis done and know exactly what you had. It all really depends on what you have fun doing. Many folks would not enjoy exploring found steel like that at all. Many others would.
Those who do like to do that sort of thing often fall into a few camps (from my observation): the naive amateur, the primitive-crafts craftsman and/or the seasoned skilled veteran who has an intimate, experienced, even intuitive knowledge of steel. We all start somewhere right. It's just a matter of deciding where one wants to start. Many folks will suggest not starting where you are making your inquiry and encourage you to get a piece of steel of a know alloy that you can then know its HT recipes for, etc. Folks will often report that the two can meet, such as by getting an analysis done, for instance.
MG: I have not made much of a study of the spark test, but many folks have. Here are a few links...
As to the heat-quench-and-snap "test". I have done that one a "few" times. It's not foolproof (now there's a term) but can sometimes put you in the ball park (or not). You know how if you took a drill bit, clamped it in a vise and hit it from the side with a hammer it would snap right in two, but if you did it with a nail the nail would just bend? It's like that.
Many high carbon steel alloys will act like the drill bit when you heat them to red hot (past it's becoming nonmagnetic) and quench it in water. If it still bends then its probably mild steel. Anyway, this can often help you discover some stuff about the steel. If you have a bunch of it and it hardens up, then it may be worth getting an analysis done so you can find out the exact composition.
You should probably take all this with the proverbial grain of salt, as it's coming from a somewhat naive amateur!
All the best, Phil