Common steel groups

Here's a short overview of the steel groups used in high-tensile applications such as axle shafts.

10xx, 11xx, 12xx, 15xx

This is the carbon steel group. Most standard axles are made of 1040 grade, generallz heat treated to 40 Rockwell in the center and 55-60 Rockwell in the outer layer of about .180 inch. They have about 1-1.65% manganese.


The manganese steel group which contains between 1.45 and 2.05% of manganese. Many aftermarket manufacturer use this as the higher manganese content allows for more flexibility during the heat treating process.


These steels contain a small amount of silicon but otherwise are similar to a standard type. Silicone adds a measure of hardness. Silicone additions are in the .15-.30% range.

43xx, 47xx

The nickel-chromium-molybdenum group. They contain between .65-.95% chromium, .2-.3% molybdenum and 1.55-2.0% nickel. Chromium increases hardness and elastic limits as well as corrosion resistance. Molybdenum and nickel also increase hardness.