Aisi 4130 Chromoly Low Alloy Steel Pipe

aisi 4130 chromoly low alloy steel Pipe

4130 chromium-molybdenum low alloy steel pipe is an engineering material with high strength, excellent toughness and good processing performance. Its core advantage lies in the alloying design of chromium (0.8-1.1%) and molybdenum (0.15-0.25%), which achieves significant performance improvement while maintaining a density of 7.85g/cm³. The material has a tensile strength of 700-850MPa and a yield strength of 500-700MPa in the quenched and tempered state, and maintains an elongation of 10-15%. Its unique alloy composition brings it three core characteristics:

Excellent balance of strength and toughness: through quenching + tempering (Q&T) treatment, a refined tempered martensite structure can be obtained, and the low-temperature impact energy of -40℃ can still be maintained above 27J, which is particularly suitable for working conditions with impact loads (such as oil drill collars and aircraft landing gear);

Excellent process adaptability: It has good hot workability (hot rolling temperature range 850-1200℃) and cold forming ability (minimum bending radius 3 times the pipe diameter), and requires 150-200℃ preheating (wall thickness > 12mm) and low-hydrogen welding materials during welding;

Economic advantage: Compared with stainless steel, it reduces costs by 30-50%, and compared with ordinary carbon steel, it increases strength by 40% and reduces weight by 15-20%.

The surface of the pipe can be sandblasted (SA2.5 grade), galvanized (≥80μm) or finely ground (Ra≤0.8μm). Typical specifications cover φ6-500mm outer diameter and 1-50mm wall thickness. It is widely used in:

High-pressure field: hydraulic cylinder (pressure ≤50MPa), power plant boiler tube (EN 10216 standard);

Mobile equipment: racing roll cage (FIA certification), crane boom (ISO 4309);

Special environment: polar equipment (-60℃ service), offshore platform (NACE MR0175 anti-sulfur corrosion).

Special attention: In acidic environment, the hardness must be strictly limited to ≤22HRC to avoid sulfide stress cracking, and it is not recommended for long-term high temperature conditions of ＞450℃. Through reasonable selection design and heat treatment process control, 4130 steel pipe can achieve the best balance between strength, weight and cost, becoming one of the preferred materials in the field of heavy-duty engineering.

1. Basic Parameters

Property	Specification
Material Grade	4130 Chromoly Steel (AISI/SAE 4130)
Density	7.85 g/cm³
Standard	ASTM A519, AMS 6371, EN 10297, GB/T 8162

2. Dimensions & Tolerances

Parameter	Range/Tolerance
Outer Diameter (OD)	6-500 mm (standard), up to 800 mm (custom)
Wall Thickness (WT)	1-50 mm
Length	6-12 m (standard), up to 18 m (custom)
OD Tolerance	±0.5% (precision), ±1.0% (commercial)
WT Tolerance	+10%/-5% (standard), +7.5%/-3.5% (precision)

3. Mechanical Properties

Property	As-Rolled	Normalized	Quenched & Tempered
Tensile Strength	≥560 MPa	≥670 MPa	700-850 MPa
Yield Strength	≥360 MPa	≥435 MPa	500-700 MPa
Elongation	≥15%	≥12%	10-15%
Hardness (HB)	170-220	200-250	250-320

4. Chemical Composition (%)

Element	Content	Element	Content
C	0.28-0.33	Cr	0.80-1.10
Mn	0.40-0.60	Mo	0.15-0.25
Si	0.15-0.35	P (max)	0.035
S (max)	0.040	Fe	Balance

5. Surface Treatments

Treatment	Characteristics
Black Oxide	Basic corrosion protection
Shot Blasting	SA 2.5 cleanliness, improves coating adhesion
Pickling	Removes scale, prepares for plating
Galvanizing	Hot-dip zinc coating for outdoor applications
Polishing	Ra ≤0.8μm for high-precision applications

6. Applications by Industry

Industry	Typical Uses
Aerospace	Landing gear components, engine mounts
Oil & Gas	Drill collars, wellhead equipment, pressure vessels
Automotive	Roll cages, drive shafts, suspension components
Power Generation	Boiler tubes, steam piping, turbine components
Heavy Machinery	Hydraulic cylinders, crane booms, excavator arms

7. Comparison with Similar Materials

Property	4130 Pipe	4140 Pipe	Carbon Steel Pipe
Tensile Strength	670-850 MPa	850-1000 MPa	400-550 MPa
Weldability	Good (preheat req.)	Fair (strict controls)	Excellent
Cost	Medium	High	Low
Typical Uses	Structural	High-stress parts	General purpose

Chemical Composition

The chemical composition of AISI 4130 alloy steel is listed in the following table.

Element	Content (%)
Iron, Fe	97.03 – 98.22
Chromium, Cr	0.80 – 1.10
Manganese, Mn	0.40 – 0.60
Carbon, C	0.280 – 0.330
Silicon, Si	0.15 – 0.30
Molybdenum, Mo	0.15 – 0.25
Sulfur, S	0.040
Phosphorous, P	0.035

AISI 4130 Pipe Sizes

O.D. x Thickness in milimeter	O.D x Thickness in milimeter	O.D x Thickness in milimeter
38.1 x 3.2	57.0 x 4.9	76.2 x 4.0
38.1 x 4.0	57.0 x 6.3	76.2 x 5.0
38.1 x 6.3	57.0 x 7.9	76.2 x 6.3
42.4 x 3.2	60.3 x 3.2	82.5 x 4.5
42.4 x 4.0	60.3 x 3.6	88.9 x 3.2
44.5 x 3.2	60.3 x 5.0	88.9 x 3.6
44.5 x 6.3	63.5 x 3.2	88.9 x 4.0
48.3 x 3.2	63.5 x 3.6	101.6 x 3.6
48.3 x 3.6	63.5 x 4.0	101.6 x 4.5
50.8 x 4.5	63.5 x 6.3	101.6 x 6.3
51.0 x 3.2	63.5 x 7.9	114.3 x 3.6
51.0 x 3.6	70.0 x 3.2	114.3 x 5.0
51.0 x 6.3	70.0 x 3.6	139.7 x 4.0
57.0 x 3.2	70.0 x 6.3	139.7 x 5.0
57.0 x 3.6	76.2 x 3.6	139.7 x 6.3

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1. What is AISI 4130?

AISI 4130 is a chromoly steel, also known as chrome moly steel. It's a medium-carbon, low-alloy steel popular for its balance of strength, toughness, and machinability.
2. Is chrome-molybdenum steel better than steel?
What distinguishes chrome-molybdenum steel from other types of steel is its higher tensile strength. This means it can withstand greater forces without breaking or deforming. It also has better corrosion resistance, making it ideal for applications exposed to harsh environments or moisture.
3. Will 4130 chrome-molybdenum steel rust?
Both 4140 and 4130 steels are low-alloy steels that have excellent strength, toughness, and corrosion resistance.
4. Is 4130 a carbon steel?
4130 carbon steel is a low-carbon steel with a carbon content of approximately 0.3%. 4130 is also an alloy steel with chromium and molybdenum as strengthening agents. This steel is easy to weld and can be heat treated more easily than other mild steels.

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