ASTM/ASME Standard Alloy Pipes
AISI 4140 is a chromium molybdenum alloy steel specification widely used in the oil and gas industry. Similar to grade AISI 4130 but with a slightly higher carbon content.
American Iron and Steel Institute (AISI 4140) is a member of the low alloy tool steel family characterized by small quantities of trace elements added to an otherwise simple steel. These trace elements, when compared with more simple steel such as 1040, improves the characteristics of 4140 . However, because 4140 remains relatively simple, it is used in a wider range of applications than more specialized tool steels like the D or S series of steel.
Heat Treatment
AISI 4140 has enough carbon present to allow for adequate heat treatment. Recommended hardening procedures are to bring the steel up to 1,675 degrees Fahrenheit for normalization (removal of stress within the steel). After it cools properly, heat the steel to 1,550 degrees Fahrenheit before quenching it in oil. The toughness of the steel makes machining in its hardened form difficult. However, after annealing the steel at 1,600 degrees followed by a slow cooling, the steel is much softer and far easier to machine. It can then be heat-treated after machining to produce a hard, precise item.
Applications