Eric,
Here's part of an article on welding 5160:
Low-Alloy Chromium Steels
Included in this group are the AISI type 5015 to 5160 and the electric furnace steels 50100, 51100, and 52100. In these steels carbon ranges from 0.12-1.10%, manganese from 0.30-1.00%, chromium from 0.20-1.60%, and silicon from 0.20-0.30%. When carbon is at low end of the range, these steels can be welded without special precautions. As the carbon increases and as the chromium increases, high hardenability results and a preheat of as high 400oC will be required, particularly for heavy sections.
When using the submerged arc welding process, it is also necessary to match the composition of the electrode with the composition of the base metal. A flux that neither detracts nor adds elements to the weld metal should be used. In general, preheat can be reduced for submerged arc welding because of the higher heat input and slower cooling rates involved. To make sure that the submerged arc deposit is low hydrogen, the flux must be dry and the electrode and base metal must be clean.
When using the gas metal arc welding process, the electrode should be selected to match the base metal and the shielding gas should be selected to avoid excessive oxidation of the weld metal. Preheating with the gas metal arc welding (GMAW) process should be in the same order as with shielded metal arc welding (SMAW) since the heat input is similar.
When using the flux-cored arc welding process, the deposited weld metal produced by the flux-cored electrode should match the base metal being welded. Preheat requirements would be similar to gas metal arc welding.
When low-alloy high-strength steels are welded to lower-strength grades the electrode should be selected to match the strength of the lower-strength steel. The welding procedure, that is, preheat input, etc., should be suitable for the higher-strength steel.
Source:
http://www.key-to-steel.com/default.aspx?ID=CheckArticle&NM=68
I couldn't find a referance handy for what type of rod to use - but upon further reflection, I would use this blade for "display only" or testing a new profile. If you have access to a dye-pen kit and decide to test it - could you post the results? That test would be very informative for all!
Thanks!