With so many different alloys available, it can be difficult to determine which one is best for your parts. There are numerous factors that influence which steel alloy is the best.
Despite the fact that there are hundreds of different steel alloys, the majority of CNC machined parts use only about 10-12 different alloys.
The best machinability is found in carbon steel alloys with added lead (typically 0.2%). These alloys are also referred to as "free-machining steel alloys."
The most common free-machining alloy steel is 12L14 steel. This metal is ideal for complex part designs with tight tolerances. Because of the lead and sulfur, 12L14 can be machined quickly and efficiently, and a smooth finish is easily achieved. 12L14 steel is frequently used as the standard machining cost factor against which other materials are measured.
Alloy steels 4130 and 4140 are also popular for machined parts. These alloys are more expensive to machine, but they are stronger and wear resistant. These alloys are frequently used in automotive, military, and aircraft components. They are extremely fatigue resistant, making them ideal for engine and transmission parts that must maintain strength in high-stress environments.
