Some more axle lore from various older posts, better consolidated here: "Here's part of the scoop on original axles--they were indeed heat treated. Marco says EE and one of the several A style Ford steels were used on A's. All the '32-36 types I have visible show EE-1 forged in, dunno if the one is a variant recipe or a heat treat type indicator or what... I went fishing last night in one of my deeper information bunkers and dug up "Metallurgy and Metallography", a textbook from the Ford Apprentice School published in 1934. This is a fairly heavy duty chem and metal tech book, probably a mid or high level class text for people headed into the Ford foundry system. It's not the total word on every metal process at Ford, of course, but it does have some excellent info for us. There's a huge chart calling out many types of steel and iron, mostly for manufacturing but some special for dies, tools, and standard hardware too. A few show SAE numbers, I assume the rest are purely Ford specs since Ford was essentially self-sufficient and was pioneering new casting and forging stuff at this time. Type EE shows carbon .30-.40, manganese .70-.90, silicon .07-.15, phosphorus .03 max, sulfur.05 max...stock to be ID'ed by yellow paint! The various A styles all seem to have chromium and of course several variants of different alloying specs. On heat treat, the book gives a single process for EE based stuff, calling it satisfactory for all uses of EE but noting that other processes exist and might be specified for various particular uses. Heat treat is so for this particular process: Heat to 1470-1500, quench in brine or caustic; strain draw in oil 350-375 degrees; draw temper if so specified. Notes below say that a specific characteristic this steel is chosen for is to RESIST TORQUE, bringing it right on topic here! At any rate, our original axles were indeed speciall treated and chosen steel in all ways, and some of that torque resistance is doubtless long gone from our beloved ancient dropped pieces." So there were 2 alloys used, AA and EE (electric furnace) steel, though all I have carry the EE marks. I think Metallurgy book has AA specs too. Almost all Ford steels were Ford formulas, chart shows very few SAE steels. BRUCE LANCASTER, JAN 8, 2008EDITDELETE!REPORT!
That's why maybe some axles there are easy to drop than others? You realized since then when you put the torch first on the axle! And the heat zone is different than others!!! Or some heated different than others! Enviado desde mi XT1068 mediante Tapatalk
Cooling in the open air would result in "normalizing" the metal. Would that be a good thing? I guess the question to ask is, "Are OEM straight axles made of alloy steel -drop forged and then heat treated?" I see some modern straight axles have the words. "Do Not Heat" cast into them.
No they are not heat treated that makes them hard and brittle, and much more susceptible to fatigue failure. They are supposed to bend, not break
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