Project Description
AISI 4320 Steel Round Bar
AISI 4320 Steel Round Bar is a premium low-carbon, nickel-chromium-molybdenum alloy steel specifically engineered for carburizing and case hardening. Known for its exceptional ability to develop a high-hardness, wear-resistant surface while maintaining a tough, ductile core, it is highly sought after for heavy-duty mechanical components subject to severe impact and wear.
As a trusted supplier to the world’s top 10 oilfield service companies, Hunan ShunFu Metal Material Co., Ltd. specializes in manufacturing this grade for demanding oil and gas extraction and mining applications. Backed by our API Q1 and ISO 9001 certifications and extensive export experience to over 50 countries, we possess the metallurgical expertise to deliver this material with uncompromising structural integrity.
Equivalent Grades
| US / ASTM | Europe / EN | Germany / DIN | Japan / JIS | China / GB |
|---|---|---|---|---|
| AISI 4320 | 17NiCrMo6-4 | 1.6566 | SNCM420 | 20CrNiMo |
Applications
- Heavy-Duty Gear Components: Used extensively in transmission systems for mining equipment. ShunFu Metal supplies these as high-ratio forged round bars, providing an optimized grain structure ready for custom gear cutting and subsequent case hardening.
- Valve Body Forgings: Critical for high-pressure oilfield fluid control systems. We supply these as precision-machined blanks, utilizing our advanced CNC lathe and milling capabilities to meet the exact dimensional tolerances required by our global clients.
- Drill Collar Blanks and Rock Drill Steel: Essential for directional drilling and mining operations. ShunFu Metal provides these drill collar blanks as deep-hole bored hollow bars, manufactured to meet API 7-1 specifications, leveraging our in-house BTA boring and long-distance gunhole-drilling equipment to ensure perfect concentricity.
- Wear-Resistant Pins and Shafts: Utilized in downhole drilling tools where high surface wear and core impact occur simultaneously. Delivered as peeled or centerless ground round bars with guaranteed surface tolerances for immediate assembly.
Specifications & Standards
ShunFu Metal strictly organizes production in accordance with the following international standards, and we can issue comprehensive Material Test Certificates (MTC) corresponding to the required specifications upon customer request.
- ASTM A29 / A29M: Standard Specification for General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought
- ASTM A322: Standard Specification for Steel Bars, Alloy, Standard Grades
- SAE J404: Chemical Compositions of SAE Alloy Steels
- EN 10084: Case Hardening Steels - Technical Delivery Conditions
Available Sizes & Delivery
ShunFu Metal offers a versatile size range for AISI 4320 Steel Round Bar, including hot-rolled round bars (20mm–150mm), forged round bars (150mm–800mm), and custom hollow bars. Our advanced forging capabilities ensure a high forging ratio and exceptionally fine grain structure. All materials are processed using our API-compliant, regularly calibrated heat treatment furnaces and precision machining equipment, including BTA deep hole drills and CNC lathes.
- Common Grades: Ready stock available for immediate dispatch, starting from a single piece with a delivery time of approximately 7 days.
- Custom Forgings/Rolled Bars: MOQ typically starts at 3 tons, with a lead time of around 30 days.
- Small Batch Special Melts: Equipped with small induction furnaces, we can accommodate custom melts starting from 3–5 tons.
- Large Volume Orders: Supported by our 30–60 ton EAF, ensuring rapid delivery for major projects.
Chemical Composition
| Standard | C (%) | Mn (%) | P (%) | S (%) | Si (%) | Ni (%) | Cr (%) | Mo (%) |
|---|---|---|---|---|---|---|---|---|
| ASTM A322 | 0.17 – 0.22 | 0.45 – 0.65 | ≤ 0.035 | ≤ 0.040 | 0.15 – 0.35 | 1.65 – 2.00 | 0.40 – 0.60 | 0.20 – 0.30 |
| EN 10084 | 0.14 – 0.20 | 0.60 – 0.90 | ≤ 0.025 | ≤ 0.035 | ≤ 0.40 | 1.20 – 1.70 | 0.80 – 1.10 | 0.15 – 0.25 |
At ShunFu Metal, we conduct rigorous in-house spectrometry on every single heat to verify the chemical composition. This ensures all elemental contents strictly comply with specification requirements, and we can fine-tune the alloy composition during the melting phase to meet your specific mechanical performance demands.
Melting & Processing
ShunFu Metal offers flexible melting routes: standard EAF + LF + VD for excellent purity, ESR or PESR for higher demands, and VIM + VAR for the highest aerospace-grade requirements. Customers can consult with our metallurgical engineers to select the optimal melting solution for their specific application.
Mechanical Properties
| Tensile Strength (Rm) | Yield Strength (Rp0.2) | Elongation (A5) | Reduction of Area (Z) | Core Hardness |
|---|---|---|---|---|
| ≥ 1030 MPa | ≥ 735 MPa | ≥ 11 % | ≥ 40 % | 30 – 40 HRC |
Prior to delivery, ShunFu Metal provides comprehensive mechanical property test reports issued by our fully equipped, accredited laboratory. All data is fully traceable to the specific heat and batch number, guaranteeing material reliability.
Heat Treatment
| Process | Temperature Range | Cooling Method |
|---|---|---|
| Normalizing | 870°C – 925°C | Air cooling |
| Carburizing | 900°C – 925°C | Furnace cooling or air cooling |
| Core Refining / Quenching | 845°C – 870°C | Oil quench |
| Tempering | 150°C – 200°C | Air cooling |
ShunFu Metal’s heat treatment furnaces are strictly calibrated on a regular schedule in accordance with API standards. This rigorous control guarantees exceptional temperature uniformity and process repeatability, providing reliable, consistent, and highly predictable heat treatment results for every batch of AISI 4320 steel.
Surface Finish & Machining
Depending on the product application, ShunFu Metal provides comprehensive surface finishing and precision machining services. Our capabilities include rough turning, centerless grinding (achieving Ra 0.8–1.6 µm), and precision CNC milling. For downhole tools, we utilize advanced BTA boring and long-distance gunhole-drilling to produce high-precision hollow bars with tight dimensional tolerances. We also offer roller burnishing and shot peening to enhance surface fatigue resistance. By linking these capabilities directly to our factory floor, we deliver ready-to-use precision components, significantly reducing your secondary machining costs.
Quality Assurance & Inspection
ShunFu Metal implements stringent quality control throughout all production stages. Our inspection protocol includes 100% Ultrasonic Testing (UT) in accordance with ASTM A388, chemical analysis, mechanical testing, and precise dimensional checks. We perform specialized four-quadrant hardness testing and comprehensive metallographic examinations to ensure uniform case-hardening potential.
Holding API Q1 and ISO 9001 certifications means our products are manufactured under a globally recognized quality management system, ensuring absolute reliability for oilfield applications. We supply EN 10204 3.1 certificates as standard (3.2 upon request) and readily accommodate third-party inspections from agencies like SGS or TÜV.
Packing & Shipping
With export experience to over 50 countries, ShunFu Metal ensures secure global delivery. Black-surface bars are tightly bundled with steel wire. Bright and precision-machined products receive multi-layer protective wrapping and premium anti-rust oil coating to prevent corrosion during sea freight. We strictly comply with all destination port packaging and documentation requirements.
Frequently Asked Questions
Can ShunFu Metal supply AISI 4320 Steel Round Bar to ASTM specifications?
Yes, our technical team of 22 metallurgy and materials engineers ensures that every batch of AISI 4320 strictly adheres to ASTM A29 and ASTM A322 standards. This is backed by our fully equipped in-house laboratory testing and standard EN 10204 3.1 certification.
What is the minimum order quantity for AISI 4320 products?
For standard stock sizes, we offer a flexible MOQ starting from a single piece with a rapid 7-day lead time. For custom melts or specific forged dimensions, our MOQ is typically 3 tons, utilizing our small induction furnaces for highly efficient, customized production.
Do you offer pre-machining services for AISI 4320 drill collar blanks?
Absolutely. ShunFu Metal operates 45 cutting machines, advanced CNC lathes, and specialized BTA deep-hole boring equipment. We can deliver AISI 4320 as fully machined, bored, and heat-treated hollow bars, ready for your final assembly and saving you significant processing time.
What melting processes are available for high-purity AISI 4320 steel?
We offer standard EAF + LF + VD for excellent purity, ESR or PESR for higher cleanliness demands, and VIM + VAR for the most stringent aerospace-grade requirements. Consult our engineers to match the melting route to your performance needs.
How does ShunFu Metal ensure quality assurance for AISI 4320 bars?
All production is controlled under our API Q1 and ISO 9001 certified system. Inspection includes 100% ultrasonic testing per ASTM A388, chemical analysis, mechanical testing, and four-quadrant hardness checks. EN 10204 3.1 certificates are standard; 3.2 and third-party inspection are available on request.