William Duffield
I can't help you with the shear strength problem, but if you use drill blanks instead of drill rod, they come already hardened. The ones I use are M2 HSS, so they are stainless, and you can grind them to shape with whatever wheel you have laying around gathering dust. I used to get them from Enco, but when they acquired MSC, they liked their prices better, and turned off the Enco name.

https://www.mscdirect.com/browse/Holemaking/Drilling-Drill-Bits/Drill-Blanks-Sets?navid=12106172

They carry them in 64ths, metric, letter and number sizes, made in USA and imported, individual blanks and sets, but none of that is important for your application.