2060 – 07 – Plain Carbon Steel
AISI-SAE designations use four numbers to describe what is inside plain carbon steel. The first number is one, which signifies plain carbon steel. The second number shows if there is another element present, and the last two numbers are the percentage of carbon.
For example, steel labeled 1023 is a plain carbon steel, it has no added element, and it contains 0.23% carbon. The contents of 1029 steel are the same, except it has 0.29% carbon. These are both low-carbon steels.
There are three types of carbon steels. The 11XX steels are free-machining metals that contain extra sulfur. 12XX steels contain extra sulfur and phosphorus. The 15XX steels have manganese from 1.00-1.65%.