aisi 4130 alloy steel all introduction: properties, advantages, uses
aisi 4130 steel comprehensive introduction
Introduction
What is AISI 4130 Steel?
AISI 4130 steel is a type of alloy steel that is commonly used in the manufacturing industry. It is known for its high tensile strength and weldability, making it an ideal material for various applications. The AISI 4130 steel is often found in the form of tubes or bars, commonly referred to as 4130 tubing or chromoly steel tubing. One of the main advantages of using 4130 tubing is its strong yet lightweight nature, making it a popular choice for structures that require both strength and weight savings. The mechanical properties of chromoly steel, such as its hardness and machinability, can be enhanced through the proper heat treatment processes, including annealing, normalizing, and tempering. The weldability of 4130 chromoly steel is excellent, and it is resistant to cracking and deformation during the welding process. In addition, 4130 steel tubing has a higher tensile strength compared to mild steel, making it a preferred choice where a thicker wall is needed.
What is 4130 P+X steel?
4130 P+X steel is a high-strength steel that is widely used in aviation and racing. It is commonly used for structural applications in both industries because it offers an equivalent strength to the traditional mild steel while being hardened. This steel is known for its increased strength, which makes it ideal for applications where a thicker wall must be used. The 4130 P+X steel also has a clean and oxidation-free finish both on the outside and inside, making it a popular choice among motorcycle builders and race car chassis builders alike. Its equivalent strength and durability make it a preferred option in the industry. Whether it is for aviation or racing, the use of 4130 P+X steel ensures that the structural applications meet the required strength and performance standards.
What is 4130 L80 steel?
4130 L80 steel is a high-strength alloy that offers equivalent strength as the 4130 mild steel. This type of steel is hardened and tempered, which increases its strength and makes it suitable for various applications. The addition of chromium and molybdenum as strengthening agents enhances the steel’s resistance to oxidation and ensures a clean finish. When using 4130 L80 steel, it is crucial to use the equivalent strength materials in order maintain the desired level of strength. Additionally, this steel exhibits good ductility, allowing for easy forming and shaping. The Society of Automotive Engineers acknowledges the quality and performance of 4130 L80 steel, making it a popular choice in the automotive industry. However, it is important to note that machining becomes difficult when the hardness of the steel is increased. Therefore, careful consideration and appropriate processes must be employed to ensure successful machining.
What is 4130H steel?
4130H is produced in a number of product forms including tubing.4130H has been used extensively for structures such as air frames that are fabricated from tubing. 4130H is weldable, but because of its fairly high hardenability, preheating and post heating must be used
What is 4130 75ksi steel?
4130 steel round bars quenched and tempered the materials according to this specification must present a minimum yield strength of 75 Ksi. Steel must comply with AP| 6A 21st edition PSL 3, temperature class K-U material class DD, EENACE MRO175 /ISO 15156.
Application
Where is AISI 4130 steel use?
AISI 4130 steel applications in oil and gas industry:
Primary Applications:
- Wellhead components and equipment
- Downhole tools
- Drilling collars
- Subsurface safety valves
- Christmas tree components
- Tubing hangers
- Valve bodies and bonnets
- High-pressure pipelines and fittings
- Completion equipment
- Blowout preventers (BOP) components
- Pressure containing parts
Standard
What is 4130 steel standard?
AISI/SAE 4130. Chromium Molybdenum Alloy Steel.
ASTM A29/A29M. Standard Specification for General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought.
ASTM A255 Standard Test Methods for Determining Hardenability of Steel.
ASTM A370. Standard Test Methods and Definitions for Mechanical Testing of Steel Products.
ASTM A388. Standard Practice for Ultrasonic Examination of Heavy Steel Forgings.
ASTM A 700. Standard Guide for Packaging, Marking, and Loading Methods for Steel Products for Shipment.
ASTM E10. Standard Test Method for Brinell Hardness of Metallic Materials.
ASTM E18. Standard Test Methods for Rockwell Hardness of Metallic Materials.
ASTM E23 Standard Test Methods for Notched Bar Impact Testing of Metallic Materials.
ASTM E45 Standard Test Methods for Determining the Inclusion Content of Steel.
ASTM E112 Standard Test Methods for Determining Average Grain size.
EN 10204 3.1 Metallic Products – Types of inspection documents.
API 6A 21st Edition. Specification for Wellhead and Tree Equipment.
NACE MR1075 / ISO 15156. Petroleum and natural gas industries – Materials for use in H2S – containing environments in oil and gas production.
Chemical Composition
What is AISI 4130 steel 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 |
Mechanical properties
What is AISI 4130 75ksi mechanical properties?
| Tensile Strength Psi (Mpa) |
Yield Strength Psi(Mpa) |
Elongation (2″)
% |
Reduction of area % |
Charpy Impact Average -60℃.Joules |
Hardness HRC(HB) |
|
| Min. | 95000(655) | 75000(517) | 17 | 35 | 27 | 17(207) |
| Max. | 一 | 22(237) |
Heat treatment
What is AISI 4130 steel heat treatment?
Normalizing. Heat to 900 °C (1650 °F). Cool in air
Annealing. For a predominately pearlitic structure, heat to 855 °C (1570 °F), cool fairly rapidly to 760 °C (1400 °F), then to 665 °C (1230 °F) at a rate not to exceed 18 °C (35 °F) per h; or heat to 855 °C (1575 °F), cool rapidly to 675 °C (1245 °F), and hold for 4 h. For a predominately spheroidized structure, heat to 750 °C (1380 °F), cool from 750 °C (1380 °F) to 665 °C (1230 °F) at a rate not to exceed 6 °C (10 °F) per h; cool rapidly from 750 °C (1380 °F) to 675 °C (1245 °F), and hold for 8 h
Hardening. Austenitize at 870 °C (1600 °F), and quench in oil
Tempering.
Reheat to the temperature which will result in the required hardness
Equivalent
What is 4130 steel equivalent to?
Other designations that are equivalent to AISI 4130 alloy steel include the following;
| AMS 6348 | AMS 6371 | ASTM A331 | ASTM A829 | DIN 1.7218 |
| AMS 6350 | AMS 6373 | ASTM A506 | MIL S-18729 | UNI 25 CrMo 4 |
| AMS 6351 | AMS 6374 | ASTM A507 | MIL S-6758 | JIS SCCrM 1 |
| AMS 6360 | AMS 6528 | ASTM A513 | SAE J1397 | JIS SCM 2 |
| AMS 6361 | AMS 7496 | ASTM A519 | SAE J404 | SS 2225 |
| AMS 6362 | ASTM A29 | ASTM A646 | SAE J412 | B.S. CDS 110 |
| AMS 6370 | ASTM A322 | ASTM A752 | AFNOR 25 CD 4 (S) | SAE J770 |
Similar Steels (U.S. and/or Foreign)
4130.UNS G41300; AMS6350, 6356, 6360, 6361, 6362, 6370, 6371, 6373; ASTM A322. A331 A505, A513, A519,A646:MIL SPEC MIL-S-16974;SAE J404,J412.J770: (Ger.) DIN 1.7218; (Fr.) AFNOR 25 CD 4(S); (ltal.) UNI 25 CrMo4.25 CrMo 4 KB: (Jap.) JlS SCM 2,SCCrM 1; (Swed.) SS142225;(U.K.)B.S.CDS 110.4130H. UNS H41300;ASTM A304; SAE J407;(Ger.) DIN1.7218, (Fr.) AFNOR 25 CD 4(S); (ltal.) UNI 25 CrMo 4, 25 CrMo 4 KB;(ap,) JIS SCM 2,SCCrM 1;(Swed.)SS142225;(U.K.)B.S.CDS 110
Process
Melting of 4130 steel
Material shall be electric arc furnace melted, ladle refined, and vacuum degassed, AOD VOD or VAD processes.
Material shall be produced to fully killed and a fine grain practice. (With grain size 5 or finer when measured in accordance with ASTM E-112)
Minimum hot work reduction ratio shall be 4.0 to 1. The actual value shall be certified.
Material shall be capable of passing cleanliness requirement as listed below when assesses in accordance with ASTM E45 Method A
How is 4130 steel bar and tube made:
4130 steel bar and tube are made using a specific manufacturing process that involves several steps. Firstly, the mild steel is transformed into 4130 steel through a combination of alloy additions and heat treatment. This process enhances the material’s strength, allowing it to have an equivalent strength as the 4130. The high-strength properties of the 4130 steel bar and tube make them ideal for applications that require durability and reliability. Additionally, the material resists oxidation and has a clean surface, which ensures its longevity and performance. When manufacturing products that require the same level of strength as 4130 steel, it is crucial to use materials that have equivalent properties. This ensures that the final product will have the same level of strength and performance as if 4130 steel was used. Therefore, materials used in such applications must have equivalent the equivalent strength to meet the required standards.
Recommended Processing Sequence
Forge
Normalize
Anneal
Rough machine
Austenitize and quench
Temper
Finish machine
4130 vs 4140 Chromium-Molybdenum (Chromoly) Steel Comparison
Chemical Composition Differences
4130 Steel: Contains 0.28-0.33% carbon, 0.40-0.60% manganese, and 0.80-1.10% chromium
4140 Steel: Higher carbon content (0.38-0.43%), with 0.75-1.00% manganese and 0.80-1.10% chromium
Mechanical Properties Comparison
4130: Tensile strength 560-670 MPa, good weldability and formability
4140: Higher tensile strength (655-1020 MPa), superior hardness and fatigue resistance
Common Applications
4130: Aircraft components, automotive frames, and structural tubing
4140: High-stress components like gears, axles, drill collars, and hydraulic shafts
Machining and Heat Treatment
4130: Easier to machine in annealed condition, responds well to normalizing
4140: Requires pre-heating for welding, achieves higher hardness through quenching
Cost and Availability
4130: More cost-effective for general engineering applications
4140: Premium pricing justified by enhanced strength characteristics
Density Characteristics of 4130 Chromium-Molybdenum (Chromoly) Steel
Basic Density Measurement
4130 steel has a density of 7.85 g/cm³ (0.284 lb/in³) at room temperature, typical for chromium-molybdenum alloys.
Factors Affecting Density
1. Alloy composition consistency
2. Heat treatment processes
3. Material processing methods (rolled/forged/cast)
Comparison with Common Materials
• 4130 vs aluminum: 45% denser than 6061-T6 (2.7 g/cm³)
• 4130 vs stainless steel: 3% lighter than 304 stainless (8.0 g/cm³)
• 4130 vs titanium: 77% denser than Grade 5 Ti (4.43 g/cm³)
Engineering Significance
The density value is crucial for:
– Weight calculations in aerospace applications
– Strength-to-weight ratio analysis
– Structural load modeling
– Transportation cost estimations
4130 Chromoly Steel Weldability Analysis
Key Weldability Factors
• 0.28-0.33% carbon content range
• Chromium-molybdenum alloy composition
• Typical applications (thin-wall vs thick-section)
Recommended Welding Processes
1. Gas Tungsten Arc Welding (GTAW/TIG): Preferred for critical applications
2. Gas Metal Arc Welding (GMAW/MIG): Production welding
3. Shielded Metal Arc Welding (SMAW): Field repairs
Preheat Requirements
• Thin sections (<6mm): 150-200°C (300-400°F)
• Thick sections: 200-315°C (400-600°F)
• Interpass temperature control: ≤315°C (600°F)
Filler Metal Selection
• ER80S-D2 (AWS A5.28)
• E8018-B2 (AWS A5.5)
• Matching composition filler alternatives
Post-Weld Heat Treatment
• Stress relieving: 595-675°C (1100-1250°F)
• Full annealing: 830-885°C (1525-1625°F)
• Normalizing procedures
Common Welding Challenges
• Hydrogen-induced cracking prevention
• Heat-affected zone (HAZ) softening
• Residual stress management
4130 Chromoly Steel Bar Applications by Shape
4130 Flat Bar Typical Uses
• Structural mounting plates in aerospace assemblies
• Automotive chassis reinforcement components
• Industrial machinery wear plates
• Custom tooling and jig fabrication
• Defense equipment mounting systems
4130 Round Bar Common Applications
• Rotating shaft components (pump/gear shafts)
• Hydraulic cylinder rods
• High-stress fastener stock
• Precision machined bushings
• Motor sport suspension linkages
Shape-Specific Advantages
Flat Bar:
– Optimized for bending loads
– Simplified welding integration
– Surface grinding compatibility
Round Bar:
– Superior torsional strength
– Turned/machined surface finish
– Dynamic load performance
4130 Chromoly Square Tubing Technical Specifications
Structural Characteristics
• Cold-drawn seamless construction
• Typical sizes: 12.7mm-152.4mm (0.5″-6″) outer dimensions
• Wall thickness range: 1.2mm-12.7mm (0.049″-0.5″)
• ASTM A513/A519 compliance
Performance Advantages
• Superior strength-to-weight ratio vs mild steel
• Enhanced torsional rigidity
• Uniform stress distribution at corners
• Consistent mechanical properties through 90° bends
Common Engineering Applications
• Motorsport roll cage construction
• Aircraft structural frameworks
• Material handling equipment
• High-performance bicycle frames
• Defense system enclosures
Fabrication Considerations
• Notch sensitivity management at miters
• Recommended bend radius: 3× material thickness minimum
• Stress relief requirements after welding
• Plasma/Laser cutting parameter optimization
Quality Verification
• Ultrasonic wall thickness verification
• Hardness testing: 85-95 HRB typical
• Surface finish requirements: 125-250 μin Ra
• Straightness tolerance: 1.5mm/m maximum
SAE 4130 vs AISI 4130 Steel Specification Analysis
Terminology Origin
• AISI 4130: American Iron and Steel Institute legacy designation
• SAE 4130: Society of Automotive Engineers standardization
Key Similarities
• Identical chemical composition requirements
• Same mechanical property standards
• Interchangeable material certification
• Equivalent heat treatment protocols
Technical Differences
1. Governing Specifications:
– SAE J404/J1397 (Current)
– AISI 1941 Standards (Historical)
2. Certification Documentation:
– SAE: EN10204 3.1/3.2
– AISI: Legacy MIL-Specs
Modern Usage Context
• SAE designation preferred in automotive/aerospace
• AISI terminology remains in older blueprints
• Identical material stock from global mills
Verification Testing
• Same chemical analysis methods (ASTM E415)
• Identical tensile testing procedures (ASTM E8)
• Unified hardness measurement standards (ASTM E10)
Shape
4130 SHEETAND 4130 PLATE
4130 sheets and plate are commonly produced in36”x72”dimensions.The best pricing is always when you order full sheets,which can be cut foreconomical shipping methods. 4130 sheet and plate are available in both Normalized Condition,which is harder and stronger,and Annealed Condition,which is softer and formable.
4130 Normalized meets the aerospace specification AMS 6345,and 4130 Annealed meets AMS 6350.
In the past, many people used MIL-S-18729 as the common specification,but it did not differentiate between Normalized or Annealed conditions. MIL-S-18729 was can celled in 1997,superseded by AMS6345 and AMS 6350.
4130 Sheet and Plate Typical Mechanical Properties:
| Annealed | Normalized up to .062″-.187″ |
Norma zed over 1.50″ |
|
| Tensile Strength (psi) | 85,000 max | 95,000 min | 90,000 min |
| Yield Strength (psi) | 75,000 | 70,000 | |
| Elongation(%in 2″) | 8-12 | 15-18 |
Quality
Surface quality
Products shall be free of cracks, laps, seams or other defects. Surface defects shall be limited to diameter 100 to 230 mm maximum depth of surface defects 1% of the diameter and for the forged diameter >230 mm maximum depth of surface defects 2% of the diameter. Products containing any of these defects more than specified range shall be considered discrepant and are cause for rejection. Surface conditioning by heavy grinding should be avoided; light dressing is allowable but should be well blended. it shall be limited to5% of the surface area and not to render the bar under the bottom limit of the diameter tolerance at any point.
Ultrasonic Testing
Ultrasonic examination shall be performed in accordance with the flat-bottom hole procedures specified in ASTM A388/A388M (except that the immersion method may be used) and ASTM E127Where variation in acoustic response of 2 dBs occurs due to surface finish difference between the test block and the part to be examined, a coupling compensation of up to 12 dB maximum shall be performed. Material shall be ultrasonic tested (100% volume of each bar) full length after completion of heat treatment. The scan must be a 360 degree scan of the OD. Forged bars of all diameters and rolled bars up to and included 8″ diameter must be capable of meeting a the requirements of API 6A-PSL 3
QTC
When using a Qualification Test Coupon, it shall be of dimensions 8″x8″x10″. The test samples shall be secured from the % thickness location of this coupon. 2 separate HBN readings shall be obtained from the surface of the QTC and reported. The reduction ratio of the QTC must not be greater than that of the production bars.
Actual data
4130 steel from Fushun
Top 4130 Chromoly Tubing Suppliers Worldwide
North American Suppliers
1. Alro Steel – Leading US metals service center with multiple alloy grades
2. OnlineMetals® – E-commerce supplier offering precision-cut tubing
3. Metal Supermarkets – Franchised supplier with 100+ North American locations
European Specialists
4. Thyssenkrupp Materials – German industrial giant’s materials division
5. Tubacex Group – Spanish leader in high-performance alloy tubing
6. Voestalpine Böhler Welding – Austrian specialty steel provider
International Suppliers
7. Shunfu Metal – China-based manufacturer specializing in aerospace-grade 4130 chromoly tubing with:
• ISO 9001-certified production
• Global distribution network
• Custom cutting/processing services
• Competitive OEM pricing
8. Prosaic Steel and Alloys – Indian exporter of pressure vessel-grade tubing
9. Nippon Steel Trading – Japanese multinational’s metal solutions division
10. Atlas Steels Australia – Asia-Pacific’s leading alloy distributor