Project Description
AISI 4147 Steel Round Bar – Premium Chrome-Molybdenum Grade for Oil & Gas Applications
Executive Summary
AISI 4147 steel stands as the industry benchmark for high-strength oilfield applications requiring 150-180 ksi yield strength after quenching and tempering. Unlike standard carbon steels, this chrome-molybdenum composition provides uniform hardening throughout thick sections up to 8 inches diameter, making it indispensable for drill collar manufacturing, tool joints, and heavy-duty wellhead components.
SHUNFU METAL manufactures AISI 4147 bars in compliance with API Specification 6A and API Specification 7-1 standards. Our supply formats include rough turned, peeled, and precision-forged conditions, all subjected to mandatory ultrasonic testing per ASTM A388 to guarantee internal soundness. Our manufacturing capabilities ensure lot traceability and certified mill test certificates for every shipment.
Critical Standards & Material Equivalents
| Standard | Designation | Application Note |
|---|---|---|
| AISI/SAE | 4147 | Primary specification for North American oilfield |
| ASTM | A322 Grade 4147 | Alloy steel bars for pressure vessel service |
| API Spec 7-1 | Grade S-135 | Rotary drill stem elements (drill pipe, drill collar) |
| API Spec 6A | 75K Material Class | Wellhead and christmas tree equipment |
| DIN | 1.7220 (42CrMo4) | European equivalent for offshore applications |
| JIS | SCM440 | Japanese industrial standard |
AISI 4147 meets the stringent requirements of NACE MR0175/ISO 15156 for sour service applications when heat treated to HRC 22 maximum hardness. This compliance is critical for downhole tools operating in hydrogen sulfide environments exceeding 0.05 psia partial pressure.
Chemical Composition & Metallurgical Properties
| Element | AISI 4147 Range (%) | SHUNFU METAL Typical (%) | Metallurgical Impact |
|---|---|---|---|
| Carbon (C) | 0.45 – 0.50 | 0.47 | Provides base hardness and strength |
| Manganese (Mn) | 0.75 – 1.00 | 0.85 | Enhances hardenability, deoxidation |
| Chromium (Cr) | 0.80 – 1.10 | 0.95 | Deep hardening, corrosion resistance |
| Molybdenum (Mo) | 0.15 – 0.25 | 0.20 | Prevents temper brittleness, high-temp strength |
| Silicon (Si) | 0.15 – 0.35 | 0.25 | Deoxidizer, improves toughness |
| Sulfur (S) | ≤ 0.035 | ≤ 0.008 | Controlled for sour service compliance |
| Phosphorus (P) | ≤ 0.035 | ≤ 0.010 | Minimized for impact toughness |
SHUNFU METAL’s enhanced sulfur and phosphorus control (S+P ≤ 0.018%) significantly exceeds AISI requirements, delivering superior impact properties and weldability. Our vacuum-degassed steel exhibits inclusion ratings of Type A (Thin) ≤ 1.5, Type B (Heavy) ≤ 1.0, and Type C (Globular) ≤ 1.0 per ASTM E45 Method A.
Mechanical Properties After Heat Treatment
| Property | Quenched & Tempered (Q+T) | Test Standard | Significance |
|---|---|---|---|
| Yield Strength (0.2% offset) | 150-180 ksi (1035-1240 MPa) | ASTM A370 | Design stress for drill collar calculations |
| Tensile Strength | 180-220 ksi (1240-1515 MPa) | ASTM A370 | Ultimate load capacity |
| Elongation (2″ gage) | 12% minimum | ASTM A370 | Ductility for upset forging |
| Reduction of Area | 35% minimum | ASTM A370 | Indicates material toughness |
| Hardness | HRC 18-22 (NACE compliant) | ASTM E18 | Critical for H₂S service |
| Impact Energy (Charpy V-Notch) | 15 ft-lbs min @ -50°F | ASTM A370 | Arctic service capability |
| Grain Size | ASTM No. 5 or finer | ASTM E112 | Uniform properties, fatigue resistance |
Hardenability Characteristics
AISI 4147’s superior hardenability permits through-hardening of sections up to 8 inches diameter when oil quenched from 1550°F (845°C). The Jominy hardenability band (HRC at J=5) ranges from 50-57, ensuring consistent mechanical properties throughout thick-walled drill collars and forged blocks. Tempering at 1100-1200°F (595-650°C) achieves the optimal balance between strength and toughness for oilfield service.
Manufacturing & Quality Control Excellence
SHUNFU METAL employs advanced electric arc furnace (EAF) steelmaking combined with ladle refining and vacuum degassing to achieve superior cleanliness levels. Our forging operations utilize hydraulic presses exceeding 4000 tons capacity, ensuring minimum 4:1 forging ratios for diameter reduction and core density.
Austenitizing at 1550°F ± 25°F with oil quenching for maximum hardenability penetration
UT inspection per ASTM A388, SEP 1921 Class C/c or D/d as specified
CNC turning, BTA deep hole boring up to 40:1 L/D ratio for hollow applications
Real-time monitoring of chemistry, mechanical properties, and dimensional tolerances
Non-Destructive Testing Protocol
Every AISI 4147 bar undergoes mandatory ultrasonic examination using immersion technique with focused transducers. Our UT acceptance criteria exceeds API 7-1 requirements, rejecting any reflector exceeding 5% DAC (Distance Amplitude Correction) from depths greater than 1/4T from surface. Magnetic particle inspection (MPI) per ASTM E709 reveals surface discontinuities down to 0.005″ width.
Value-Added Processing Services
Check our hollow bar inventory for immediate availability of gun-drilled AISI 4147 bars ranging from 2.5″ to 12″ diameter with precision bore tolerances of ±0.005″. Our comprehensive processing capabilities eliminate the need for multiple suppliers:
| Process | Capability Range | Tolerance/Finish | Application |
|---|---|---|---|
| BTA Deep Hole Boring | Ø0.5″ – Ø6.0″ × 40 feet max | ±0.0015″ diameter, Ra 32μin | Drill collar manufacturing |
| CNC Rough Turning | Ø2″ – Ø20″ diameter | ±1/8″ diameter, 500μin Ra | Pre-machining for UT access |
| Centerless Peeling | Ø1″ – Ø8″ diameter | ±0.005″, 125μin Ra | Precision rounds, clean surface |
| Cut-to-Length | 6″ minimum to 40 feet | ±1/8″ length, square cut | Optimized material utilization |
| Upset Forging | Up to 3:1 area ratio | Hot forged, annealed condition | Tool joint manufacturing |
Critical Oilfield Applications
AISI 4147’s proven track record in demanding petroleum environments makes it the preferred choice for components requiring both high strength and environmental resistance:
Drill Collar Manufacturing
AISI 4147 drill collars provide essential weight-on-bit for directional drilling operations. The material’s 165 ksi minimum yield strength enables thinner wall designs while maintaining collapse resistance under extreme downhole pressures exceeding 15,000 psi. Our gun-drilled blanks eliminate the risk of center-line porosity common in conventionally drilled holes.
Tool Joint Assemblies
The superior upset forging characteristics of AISI 4147 allow for complex tool joint geometries without cracking or cold shuts. Heat treatment after forging achieves consistent hardness distribution, critical for threaded connections operating under combined tension, compression, and torsional loads.
Wellhead & Christmas Tree Components
API 6A-certified AISI 4147 blocks serve as raw material for pressure-containing wellhead equipment rated up to 15,000 psi working pressure. The material’s resistance to sulfide stress cracking ensures long-term integrity in sour gas applications containing H₂S concentrations up to 1000 ppm.
Subsea Equipment Applications
Marine environments demand materials capable of withstanding seawater corrosion while maintaining mechanical properties at temperatures ranging from -20°F to 250°F. AISI 4147’s molybdenum content provides enhanced crevice corrosion resistance compared to standard chrome-only alloys.
Available Size Range & Delivery Conditions
| Product Form | Size Range | Length Options | Surface Condition | Heat Treatment |
|---|---|---|---|---|
| Rolled Round Bar | Ø1″ – Ø6″ (25-150mm) | 12′, 20′, Random lengths | Hot rolled, descaled | Annealed or Q+T |
| Forged Round Bar | Ø2″ – Ø20″ (50-500mm) | Up to 40 feet (12 meters) | Rough turned +0.125″ | Q+T to customer spec |
| Hollow Bar (Gun-Drilled) | OD: Ø3″ – Ø12″, ID: Ø0.5″ – Ø6″ | Up to 32 feet | Turned OD, precision bore | Q+T, stress relieved |
| Forged Blocks | Square/Rectangle to 24″ × 24″ | Up to 80″ length | Rough machined faces | Normalized or Q+T |
Standard tolerances for turned bars: Diameter ±1/32″, Length +1/4″, -0″. Special tolerances available upon request with appropriate lead time adjustments.
Frequently Asked Questions
What is the maximum section size that can be through-hardened in AISI 4147?
AISI 4147 achieves through-hardening up to 8″ diameter when oil quenched from proper austenitizing temperature. For larger sections, we recommend water quenching with immediate tempering to minimize distortion and achieve uniform properties.
Can AISI 4147 be welded in the heat-treated condition?
Yes, but preheating to 400-500°F is mandatory to prevent HAZ (Heat Affected Zone) cracking. Post-weld stress relief at 1100°F for 2 hours minimum is required to restore mechanical properties in the weld zone. We recommend ER80S-D2 filler metal for matching strength levels.
What is the difference between AISI 4140 and AISI 4147?
AISI 4147 contains 0.45-0.50% carbon versus 4140’s 0.38-0.43%, resulting in approximately 20-30 ksi higher strength after heat treatment. This makes 4147 the preferred choice for high-stress applications like drill collars where maximum strength is required.
Do you provide third-party testing and certification?
Yes, SHUNFU METAL coordinates with accredited testing laboratories including Bureau Veritas, SGS, and TÜV for independent verification of mechanical properties, chemical analysis, and dimensional inspection. Certificates are issued with full traceability to original mill test reports.
What is the typical lead time for large diameter forged bars?
Forged AISI 4147 bars above 10″ diameter require 8-12 weeks from order confirmation. This includes forging, heat treatment, rough machining, UT inspection, and final testing. Expedited service is available for critical projects with appropriate scheduling coordination.
Ready to Specify AISI 4147 for Your Next Project?
Contact our technical sales team for comprehensive material recommendations, processing capabilities, and competitive pricing. SHUNFU METAL’s engineering support ensures optimal material selection for your specific application requirements.
Phone: +86-731-89903933
Email: [email protected]
Technical Inquiries: Visit our technical resource center
Request your free material specification sheet and processing capability guide today.
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.
