Project Description
AISI 4135 Steel Round Bar – Oil & Gas Grade Chromium-Molybdenum Alloy
Critical Standards & Material Equivalents
| Standard | Designation | Cross Reference | Application Scope |
|---|---|---|---|
| AISI/SAE | 4135 | Primary designation | Oil & gas structural components |
| ASTM | A29/A29M, A322 | Bar specifications | Forged and rolled bars |
| DIN | 1.7220 (34CrMo4) | European equivalent | Mechanical engineering |
| JIS | SCM435 | Japanese standard | Machine structural steel |
| API Spec 6A | K03135 | Wellhead equipment | Valve blocks, flanges |
Technical Specifications
Chemical Composition (Ladle Analysis)
| Element | Min % | Max % | SHUNFU Control | Impact on Properties |
|---|---|---|---|---|
| Carbon (C) | 0.33 | 0.38 | 0.34-0.37 | Strength vs toughness balance |
| Manganese (Mn) | 0.70 | 0.90 | 0.75-0.85 | Hardenability improvement |
| Chromium (Cr) | 0.80 | 1.10 | 0.90-1.05 | Deep hardening, wear resistance |
| Molybdenum (Mo) | 0.15 | 0.25 | 0.18-0.23 | Temper resistance, toughness |
| Sulfur (S) | – | 0.040 | ≤0.010 | Sour service compliance |
| Phosphorus (P) | – | 0.035 | ≤0.010 | Impact toughness optimization |
| Silicon (Si) | 0.20 | 0.35 | 0.25-0.32 | Deoxidation, strength |
Mechanical Properties – Quenched & Tempered Condition
📊 Tensile Properties
Tensile Strength: 95-115 ksi (655-795 MPa)
Yield Strength: 75-95 ksi (515-655 MPa)
Elongation: ≥17% in 2 inches
Reduction of Area: ≥50%
🔨 Hardness Range
As-Quenched: 45-52 HRC
Tempered (Oil & Gas): 18-22 HRC
Equivalent: 187-248 HBW
Testing: Per ASTM E18
❄️ Impact Toughness
Charpy V-Notch: ≥35 ft-lb (47 J)
Test Temperature: -50°F (-46°C)
Standard: ASTM A370
Sample Location: 1/2 radius
🔍 Grain Size Control
ASTM Grain Size: 5-8
Testing Method: ASTM E112
Inclusion Rating: Type A ≤2.5
Macro Etch: Per ASTM E381
Manufacturing & Quality Control Excellence
Electric Arc Furnace
Premium scrap selection, controlled chemistry
Forging Process
Min 4:1 reduction ratio, grain refinement
Heat Treatment
Controlled Q+T, uniform core properties
UT Inspection
100% ultrasonic testing, Class C/c
SHUNFU’s Manufacturing Advantages
Precise austenitizing at 1550-1600°F (845-870°C) with ±10°F control. Oil quenching with agitation for uniform cooling rates.
Computer-controlled tempering at 1000-1100°F (540-595°C) to achieve target hardness. Multiple temper cycles for stress relief.
Rough turning tolerance ±0.125″ (±3.2mm). Final machining capabilities to ±0.005″ (±0.13mm) for critical dimensions.
UT testing per ASTM A388 Class C/c or D/d. MT inspection per ASTM E709. Certificate per EN 10204 Type 3.2.
Value-Added Processing Services
Machining Capabilities
SHUNFU operates dedicated machining centers for oil and gas components. Our check our hollow bar inventory includes pre-machined AISI 4135 hollow bars with BTA deep hole boring capabilities up to 20 feet length.
| Service | Capability Range | Tolerance | Surface Finish |
|---|---|---|---|
| Rough Turning | Ø2″ – Ø36″ (50-915mm) | ±0.125″ (±3.2mm) | 125-250 μin Ra |
| Precision Boring | Ø1″ – Ø24″ ID (25-610mm) | ±0.005″ (±0.13mm) | 63-125 μin Ra |
| Cut to Length | 6″ – 240″ (150-6100mm) | ±0.060″ (±1.5mm) | Saw cut or machined |
| End Facing | Square or beveled | ±0.002″ (±0.05mm) | 32-63 μin Ra |
Critical Applications in Oil & Gas Industry
Primary Applications
Valve blocks, master valves, wing valves. API 6A PSL-3 compliance with 22 HRC max hardness for H2S environments.
Tool joints, drill pipe connections, stabilizers. Superior fatigue resistance under cyclic loading conditions.
Manifold blocks, connector bodies, actuator housings. Excellent corrosion resistance in seawater environments.
Premium threaded connections, casing accessories. Controlled hardness prevents galling and thread damage.
Performance in Sour Service
AISI 4135 demonstrates excellent resistance to sulfide stress cracking (SSC) when hardness is maintained below 22 HRC. The chromium-molybdenum chemistry provides optimal temper resistance, allowing controlled tempering to achieve NACE compliance without sacrificing mechanical properties. Our ShunFu manufacturing capabilities ensure consistent hardness distribution throughout the cross-section.
Size Range & Delivery Specifications
| Form | Diameter Range | Length Range | Surface Condition | Delivery State |
|---|---|---|---|---|
| Hot Rolled Round | Ø2″ – Ø12″ (50-305mm) | 12′ – 20′ (3.7-6.1m) | Hot rolled scale | Normalized or Q+T |
| Forged Round | Ø3″ – Ø36″ (75-915mm) | 6′ – 20′ (1.8-6.1m) | Forged scale | Q+T condition |
| Rough Turned | Ø2.5″ – Ø35″ (63-890mm) | 6′ – 20′ (1.8-6.1m) | Machined ±0.125″ | Q+T, UT tested |
| Hollow Bar | Ø4″ – Ø24″ OD (100-610mm) | 6′ – 20′ (1.8-6.1m) | BTA bored ID | Q+T, UT Class C/c |
| Cut Lengths | Per customer spec | 6″ – 240″ (150-6100mm) | Saw cut or machined | Q+T condition |
FAQ – AISI 4135 Procurement Guide
Material Specifications
Q: What heat treatment condition is standard for oil and gas applications?
A: Q+T (Quenched and Tempered) condition with hardness 18-22 HRC is standard for NACE compliance. We provide material certificates showing actual hardness values and impact test results.
Q: Can SHUNFU provide third-party inspection certificates?
A: Yes, we arrange SGS, TUV, or customer-specified inspection agencies. All testing per ASTM standards with witnessing available for critical applications.
Q: What is the maximum diameter with guaranteed core properties?
A: Our controlled cooling quench lines handle up to 36″ diameter with uniform hardness ±2 HRC throughout the cross-section. Core impact values meet specification at 1/2 radius location.
Quality Assurance
Q: What ultrasonic testing standard do you follow?
A: We perform UT per ASTM A388 Class C/c as standard. Class D/d or customer-specific acceptance criteria available upon request. 100% volumetric inspection with calibrated equipment.
Q: How do you control sulfur and phosphorus for sour service?
A: Our electric furnace practice targets S≤0.008% and P≤0.008%, well below NACE limits. Vacuum degassing and calcium treatment ensure low inclusion content.
Ready to Source AISI 4135 for Your Next Project?
Get technical consultation from our metallurgy team. Fast quotes within 24 hours. ISO 9001:2015 certified manufacturing with full traceability.
We are committed to integrate steel resources in china and serve the global steel market. Our company has more than 15 years of experience in steel researching, production, managing and sales. And our team mostly are based on and worked in national famous steel enterprise before. In the aspect of resources and information, we have established cooperative relationship with nearly hundred enterprises, either state-owned or private owned in China.
What’s more, we have built long, deep and close business relationship with dozens of steel company, Sharing and holding equities with several steel enterprises. Because of the close cooperation with steel companies and our pioneering spirit, which can ensure us stay at the top competition, and ensure our customers get what they really want. We provide preffesional one-stop service to the Contractors of follows project:
- Oil and Gas Pipeline Construction
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Our ability to purchase materials directly from leading mills at the best possible price will give you the competitive edge. This coupled with a skilled workforce dedicated to embracing the demands of the markets we serve. Just give us a call +86-731-89903933.
