Railroad Spike Analysis

Blacksmiths like to take railroad spikes and reforge them into other items. So what kind of steel are they to start with. Here is some information collected from searching the Internet.

Prior to 1926 railroad spikes were made from wrought iron

After 1926 they were made from a mild steel.

After about 1974, all rail road spikes were made from the higher carbon mix. What is not clear is when did they start to make "HIGH CARBON" spikes. I suspect that there was a period of time when both mild steel and "HIGH CARBON" spikes were made. Another point to remember here, is that although they only made the "HIGH CARBON" spikes after 1974, the manufacturers, suppliers, and railroads probably had large quantities of the mild steel spikes and it probably took many years to use up those supplies. They were not about to go and throw them away after 1974.

There seems to be a problem when discussing railroad spikes with the term "HIGH CARBON". The spikes are often stamped "HC" and commonly referred to as "HIGH CARBON". But what it is, is that they are "HIGHER" carbon then the earlier made spikes. They are NOT a high carbon steel as generally accepted in metallurgical circles (according to Metallurgy Fundamentals by Brandt and Warner, medium carbon steel containes from 0.35% to 0.50% carbon and high carbon steel has greater than 0.50% carbon). These spikes are "HIGH CARBON" as far as the railroad industry is concerned.

The following seems to be a generally accepted analysis of "HIGH CARBON" railroad spike steel (pulled from the archives of TheForge):

Carbon - 0.296%
Manganese - 0.68%
Phosphorous - 0.016%
Sulfur - 0.038%
Silicon - 0.244%
Copper - 0.287%
Nickel - 0.09%
Chrome - 0.13%
Tin - 0.001%
Aluminum - 0.005%
Vanadium - 0.022%
Cobalt - 0.008%

Therefore, based on the metallurgical standard, "HIGH CARBON" railroad spikes do not even make it to the bottom end of medium carbon steel.

-- AlbinDrzewianowski - 13 Apr 2009