Aircraft quality 4130 steel is a medium carbon, low alloy steel containing 0.15/0.25% molybdenum and 0.80/1.10% chromium as strengthening agents. With a relatively low carbon content of 0.28/0.33%, it offers exceptional weldability. With the proper heat treatment it is also readily machined. Annealing 4130 steel offers excellent ductility. It can also be normalized or otherwise heat treated.

4130 steel alloy is used primarily in the construction of commercial and military aircraft and ground support systems as well as automotive, race cars, off road, hydraulic tools, and machine tool applications. It is an intermediate strength material. Lighter gauge offer lighter weight but still maintain great strength, making it excellent for auto racing and aerospace. Engineers also use 4130 steel for parts such as pins used to secure a critical assembly. These pins are designed to fail at a specific yield in order to avoid a catastrophic failure, and 4130 steel stands up to this test.

4130 Alloy Steel Tubing is Cold Drawn and Seamless. 4130 alloying elements include Chromium and Molybdenum, and for this reason, it is commonly referred to as Chromoly or Chrome Moly. It is widely used in the Aviation and Racing Industries because it has an excellent strength to weight ratio, it is very malleable and it is very easy to weld. 4130 Chromoly, Alloy Steel Tube, is resistant to scaling and oxidation and has a clean, smooth finish on both the inside and the outside of the tubing.

AISI 4130 is a chromium molybdenum alloy steel. AISI 4130 is supplied as round bar in the hardened and tempered condition to 18-22HRc range. AISI 4130 is suitable for a variety of applications in the oil and gas sector. This material can be supplied to AISI steel tandards



Principal Design Features
AISI 4130 is a low alloy steel containing molybdenum and chromium as strengthening agents. The carbon content is nominally 0.30% and with this relatively low carbon content the alloy is excellent from the fusion weldability standpoint. The alloy can be hardened by heat treatment.

Applications
Typical applications for 4130 low alloy steel include. structural use such as aircraft engine mounts and welded tubing applications.

Machinability
This alloy is readily machined by conventional methods. Machinability is best with the alloy in the normalized and tempered condition. Although the alloy may be machined in the fully heat treated condition, machinability becomes more difficult with increasing strength (hardness) of the alloy.

Forming
Formability is best in the annealed condition for which the ductility is very good, Bend radii of 1t on annealed sheet material may be made.

Welding
4130 alloy is noted for its weldability by all of the commercial methods.

Heat Treatment
Heating at 1600 F followed by an oil quench will harden the 4130 alloy. For best results a normalizing pre-hardening heat treatment may be used at 1650 to 1700 F followed by the 1600 F soak and oil quench.



Forging
Forge at 2200 F maximum down to 1750 F.

Hot Working
4130 in the annealed condition has excellent ductility. Thus it is usually not necessary to do hot working to form parts. If hot working is needed it can be done in the range of 2000 F to 1500 F.

Cold Working
Cold working by conventional methods is readily accomplished on this alloy.

Annealing
4130 (and most of the other low alloy steels) may be annealed at 1550 F for a time long enough to allow thorough heating of the section size. It should then be cooled in the furnace at a rate of less than 50 F per hour down to 900 F, followed by air cooling from 900 F.

Tempering
Tempering is done to restore some of the ductility that may be lost after the hardening heat treatment and quench. Alloy 4130 is tempered at between 750 F and 1050 F, depending upon the strength level desired. The lower the tempering temperature the greater the strength.

Hardening
Hardening is accomplished by heat treatment or by cold working -- see "Heat Treatment".

France: AFNOR 25 CD 4 (S) 
Germany: DIN 1.7218 
Italy: UNI 25 CrMo 4 , UNI 25 CrMo 4 KB 
Japan: JIS SCCrM 1 , JIS SCM 2 
Sweden: SS 2225 
United Kingdom: B.S. CDS 110 
United States: AMS 6350 , AMS 6350D , AMS 6351A , AMS 6356 , AMS 6360 , AMS 6360F , AMS 6361 , AMS 6362 , AMS 6370 , AMS 6370F , AMS 6371 , AMS 6371D , AMS 6373 , AMS 6373A , ASTM A322 , ASTM A331 , ASTM A505 , ASTM A513 , ASTM A519 , ASTM A646 , MIL SPEC MIL-S-16974 , SAE J404 , SAE J412 , SAE J770 , UNS G41300

Electric Properties

AISI 4130 18-22HRc Typical Mechanical Properties