About 1117|Free-machining manganese steel. Higher manganese (1.00-1.30%) and moderate sulfur content give it good machinability without lead. Not as free-cutting as
12L14 or
1215, but meaningfully better than
1018. The real advantage is that 1117 can be carburized for case hardening, giving you a free-machining steel that also takes a hard case. This makes it useful for high-volume parts that need both easy machining and surface hardness, like small gears, pins, and bushings. Available in both leaded (
11L17) and non-leaded versions. Welds better than the 12xx series due to lower sulfur. Compare to 1215 (better machinability but can't case-harden), 12L14 (best machinability but leaded and no case-hardening), and
8620 (better case-hardening properties but harder to machine).
