Project Description
AISI 4337 Steel Round Bar – Premium Oil & Gas Nickel-Chrome-Moly Alloy
Executive Summary: AISI 4337 represents the premium tier of nickel-chrome-molybdenum alloy steels specifically engineered for critical oilfield applications. This grade delivers exceptional hardenability, superior impact resistance at low temperatures, and proven resistance to hydrogen sulfide environments per NACE MR0175. ShunFu Metal supplies 4337 in forged and rolled conditions with guaranteed full-section mechanical properties up to 12-inch diameter.
Critical Standards & Material Equivalents
AISI 4337 steel complies with multiple international specifications, ensuring global procurement flexibility:
| Standard | Designation | Oil & Gas Application |
|---|---|---|
| AISI/SAE | 4337 | API Spec 7-1 (Drill Collar Grade) |
| ASTM | A322 Grade 4337 | API 6A (Wellhead Equipment) |
| DIN | 1.6582 (40NiCrMo7) | Subsea Component Grade |
| JIS | SNCM439 | High-Pressure Service |
| EN | 40NiCrMo7 | Sour Service Applications |
This grade specifically meets API Spec 7-1 requirements for drill collar manufacturing and is pre-qualified for NACE MR0175/ISO 15156 sour service applications when properly heat treated to maintain hardness ≤22 HRC.
Chemical Composition – Precision Controlled for Oilfield Performance
ShunFu Metal maintains tighter chemistry controls than standard specifications to ensure consistent hardenability and sulfide stress cracking resistance:
| Element | AISI Specification (%) | ShunFu Typical (%) | Impact on Performance |
|---|---|---|---|
| Carbon (C) | 0.35 – 0.43 | 0.38 – 0.41 | Optimized for Q+T response |
| Manganese (Mn) | 0.60 – 0.90 | 0.70 – 0.85 | Enhanced hardenability |
| Phosphorus (P) | ≤ 0.035 | ≤ 0.010 | Superior toughness |
| Sulfur (S) | ≤ 0.040 | ≤ 0.008 | SSC resistance |
| Silicon (Si) | 0.15 – 0.35 | 0.20 – 0.30 | Deoxidation control |
| Nickel (Ni) | 1.65 – 2.00 | 1.70 – 1.90 | Low-temp toughness |
| Chromium (Cr) | 0.70 – 0.90 | 0.75 – 0.85 | Corrosion resistance |
| Molybdenum (Mo) | 0.20 – 0.30 | 0.22 – 0.28 | Temper resistance |
Critical Note: Our ultra-low S and P content (≤0.010%) significantly exceeds industry standards, providing superior resistance to hydrogen sulfide cracking in sour gas environments. This chemistry control is maintained through secondary refining processes including ladle metallurgy and vacuum degassing.
Mechanical Properties – Quenched & Tempered Condition
All mechanical properties are guaranteed after proper quenching and tempering heat treatment. ShunFu Metal certifies full-section properties up to 12-inch diameter:
Room Temperature Properties
| Property | Specification | Test Method | Typical ShunFu Results |
|---|---|---|---|
| Yield Strength (0.2%) | 758 MPa (110 ksi) min | ASTM A370 | 780-820 MPa |
| Tensile Strength | 895 MPa (130 ksi) min | ASTM A370 | 920-980 MPa |
| Elongation | 17% min (2-inch GL) | ASTM A370 | 18-22% |
| Reduction of Area | 50% min | ASTM A370 | 55-65% |
| Hardness | 269-321 HBW | ASTM E10 | 285-310 HBW (≤22 HRC) |
Low Temperature Impact Properties
| Test Temperature | Impact Energy (CVN) | Application |
|---|---|---|
| +20°C (+68°F) | 54 J (40 ft-lb) min | Standard service |
| -20°C (-4°F) | 41 J (30 ft-lb) min | Cold climate drilling |
| -46°C (-50°F) | 27 J (20 ft-lb) min | Arctic/Deepwater service |
These impact values position AISI 4337 as the preferred choice for subsea and Arctic drilling operations where conventional carbon steels become brittle.
Manufacturing Excellence – ShunFu’s Competitive Edge
As a direct manufacturer, ShunFu Metal controls every aspect of 4337 steel production, from raw material selection to final inspection:
Forging Ratio Control
Minimum 4:1 upset forging ratio ensures complete fiber refinement and eliminates center porosity. Our 12,000-ton hydraulic press guarantees uniform grain flow even in large-diameter bars.
Heat Treatment Precision
Computer-controlled quenching in polymer or oil media followed by precise tempering at 580-620°C. Full traceability of time-temperature profiles for each heat lot.
Grain Size Control
Guaranteed ASTM E112 grain size of 5 or finer through controlled austenitizing and quench rate optimization. Fine grain structure maximizes toughness at operating temperatures.
Quality Control & NDT Inspection
Every bar receives comprehensive non-destructive testing per the most demanding oilfield standards:
- Ultrasonic Testing: ASTM A388 or SEP 1921 Class C/c standard (2mm FBH sensitivity)
- Magnetic Particle Inspection: ASTM E709 for surface/near-surface defects
- Dimensional Inspection: ±0.8mm diameter tolerance on rough-turned bars
- Chemical Analysis: Heat analysis + product analysis per ASTM E1019
- Mechanical Testing: Longitudinal and transverse specimens per API requirements
Our quality management system operates under ISO 9001:2015 certification with specific procedures for oil and gas applications.
Value-Added Processing Capabilities
ShunFu Metal offers complete machining services to deliver drill-ready components. Our manufacturing capabilities include:
BTA Deep Hole Boring
Our specialized BTA (Boring and Trepanning Association) equipment can machine internal diameters from 25mm to 500mm with length-to-diameter ratios exceeding 40:1. Critical for drill collar and heavyweight drill pipe manufacturing.
Precision Turning Services
- Rough Turning: ±0.8mm tolerance, optimized for subsequent UT inspection
- Semi-Finish: ±0.4mm tolerance with 3.2μm surface finish
- Finish Machining: ±0.1mm tolerance per customer drawings
Heat Treatment Integration
Post-machining stress relief and final tempering available to eliminate residual stresses from heavy machining operations. Critical for maintaining dimensional stability in service.
Oilfield Applications – Where 4337 Excels
AISI 4337’s unique combination of strength, toughness, and corrosion resistance makes it indispensable for critical oilfield components:
Drill Collar Manufacturing
Preferred grade for API Spec 7-1 spiral and slick drill collars. Superior fatigue resistance under cyclic bending loads. Excellent machinability for complex tool joint connections.
Wellhead Components
Christmas tree blocks, valve bodies, and high-pressure flanges per API 6A. Proven performance at working pressures up to 15,000 psi in H2S environments.
Subsea Equipment
Blowout preventer components, subsea tree blocks, and connector bodies. Qualified for water depths exceeding 3,000 meters with temperature cycling capability.
Completion Tools
Packer mandrels, completion valve bodies, and downhole safety valve components. Resistance to stress corrosion cracking in completion fluids containing chlorides and H2S.
Sour Service Qualification
AISI 4337 meets NACE MR0175/ISO 15156 requirements for sour service when heat treated to maintain hardness ≤22 HRC. This qualification covers:
- H2S partial pressure up to 0.05 bar (0.7 psi)
- Operating temperatures from -46°C to +180°C
- Chloride concentrations up to seawater levels
- pH range from 3.5 to 10
Size Range & Delivery Specifications
| Condition | Diameter Range | Length Range | Surface Finish | UT Class |
|---|---|---|---|---|
| Hot Rolled | 76-200mm | 3-6 meters | Black/Descaled | Class C/c |
| Forged | 200-500mm | 1-4 meters | Black/Rough Turned | Class C/c or D/d |
| Rough Turned | 76-450mm | 1-6 meters | Ra 12.5μm max | Class C/c |
| Peeled | 76-300mm | 3-6 meters | Ra 6.3μm max | Class C/c |
Custom sizes available upon request. All material supplied with certified material test reports per EN 10204 Type 3.1, including complete chemical analysis, mechanical properties, and NDT results.
Technical FAQ – Addressing Common Procurement Concerns
Q: What is the maximum section size for guaranteed properties?
ShunFu guarantees full-section mechanical properties up to 12-inch (305mm) diameter in the quenched and tempered condition. For larger sections, properties are qualified on test bars removed from 1/2 radius location.
Q: Can you provide third-party inspection?
Yes, we routinely work with Lloyd’s Register, Bureau Veritas, SGS, and other internationally recognized inspection agencies. Inspection can be arranged at our facility or customer’s location.
Q: What is your typical lead time for 4337 steel?
Standard sizes (100-300mm diameter): 6-8 weeks from order confirmation. Special sizes or extensive machining: 10-12 weeks. We maintain strategic inventory of popular sizes to support urgent requirements.
Q: Do you provide material certificates for NACE compliance?
All 4337 steel is supplied with hardness verification reports and can include NACE MR0175 compliance certification when heat treated to specified hardness levels. SSC testing reports available upon request.
Why ShunFu Metal for AISI 4337 Steel
Beyond supplying premium 4337 steel, ShunFu Metal delivers the technical support and manufacturing flexibility that modern oilfield operations demand:
Manufacturing Integration
Single-source capability from steel production through final machining eliminates supply chain complexity and reduces lead times for critical drilling projects.
Technical Excellence
Our metallurgy team includes 22 engineers with combined experience exceeding 400 years in alloy steel development and oilfield applications.
Global Logistics
Established supply relationships with major drilling contractors across 52 countries. Comprehensive export packaging and documentation for international shipments.
Inventory Management
Over 8,000 tons of strategic inventory across 250 grades. Check our hollow bar inventory for immediate availability of machined components.
Ready to Specify AISI 4337 for Your Next Project?
Our technical sales team can provide detailed quotations, material availability, and application-specific recommendations within 24 hours.
Request Quote
Call: +86-731-89903933
ShunFu Metal Co., Ltd. | ISO 9001:2015 Certified Manufacturer
No. 811, Building C2, Yongsheng Commercial Plaza, Changsha, China
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
- Onshore and Offshore
- Boiler Manufacturers
- Oil Refining Equipment
- Petroleum and Chemical Plant Construction
- Fire Protection
- Heating & Air Conditioning
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.
