41xx steel is a family of
SAE steel grades, as specified by the
Society of Automotive Engineers (SAE).
Alloy
An alloy is a mixture of chemical elements of which in most cases at least one is a metal, metallic element, although it is also sometimes used for mixtures of elements; herein only metallic alloys are described. Metallic alloys often have prop ...
ing
elements include
chromium and
molybdenum, and as a result these materials are often informally referred to as chromoly steel (common variant stylings include ''chrome-moly'', ''cro-moly'', ''CrMo'', ''CRMO'', ''CR-MOLY'', and similar). They have an excellent strength to weight ratio and are considerably
stronger and
harder than standard 1020 steel, but are not easily
welded, requiring thermal treatment both before and after welding to avoid
cold cracking.
While these grades of steel do contain chromium, it is not in great enough quantities to provide the
corrosion resistance found in
stainless steel
Stainless steel, also known as inox, corrosion-resistant steel (CRES), or rustless steel, is an iron-based alloy that contains chromium, making it resistant to rust and corrosion. Stainless steel's resistance to corrosion comes from its chromi ...
.
Examples of applications for 4130, 4140, and 4145 include
structural tubing,
bicycle frames,
gas bottles for transportation of pressurized gases, firearm parts,
clutch and
flywheel components, and
roll cages. 4150 stands out as being one of the steels accepted for use in M16 rifle and M4 carbine barrels by the United States military. These steels are also used in
aircraft
An aircraft ( aircraft) is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or the Lift (force), dynamic lift of an airfoil, or, i ...
parts and therefore 41xx grade structural tubing is sometimes referred to as "aircraft tubing".
Properties
Other characteristics
One of the characteristics of this class of steel is the ability to be
case hardened by
carburization of the surface. The core of the material retains its bulk properties, while the outer surface is significantly hardened to reduce wear and tear. This makes this grade of steel an excellent material for uses such as
gears,
piston pins, and
crankshafts.
4140 Steel
4140 Steel
(Quenched and Tempered) Mechanical Properties
See also
*
4116 Krupp, not a member of this series
References
{{reflist
Steels