About 1144|Resulfurized medium-carbon steel, the base alloy for Stressproof. As plain 1144, it machines significantly better than
1018 or
1045. Sulfur creates manganese sulfide inclusions that break chips and reduce built-up edge. Rated around HRC 20 as-supplied. Stronger than mild steel (about 100-115 KSI tensile) without needing heat treatment. Good for shafts, pins, and tooling where you want easy machining and decent strength. Note: plain 1144 is not the same as Stressproof, which is a branded product with proprietary elevated-temperature drawing. Plain 1144 may not hold size as well or have the same low residual stress. Can't weld it reliably. Rusts faster than 1018 due to the sulfur. Compare to
4140 pre-hard (stronger, harder to machine) and
12L14 (easier to machine but much weaker).
