AISI 9840 (AMS 6342, UNS G98400, SAE 9840) Forging Parts | ISO 9001 Certified Forging Manufacturer in China
AISI 9840 Steel Material Overview — What Is AISI 9840 (AMS 6342, UNS G98400)?
AISI 9840 (also known as AMS 6342, UNS G98400, and SAE 9840) is a great nickel-chromium-molybdenum (Ni-Cr-Mo) alloy steel, similar to AISI 4340 but with an optimized alloy composition — lower nickel content (0.85–1.15%) but a little higher content of manganese — thus it has a better balance of mechanical performance and cost-effectiveness. This makes AISI 9840 one of the most competitive alternatives to 4340 for heavy-duty industrial forging uses. After professional precision heat treatment (quenching and tempering), AISI 9840 steel gets ultra-high tensile strength (up to 1240 MPa), good fatigue resistance, great impact toughness and wear resistance which makes it the ideal material for critical load-bearing parts designed for bad working conditions and a long service life.
Established in 1997, Jiangsu Liangyi Co.,Limited is a professional ISO 9001:2015 certified China manufacturer and global supplier of AISI 9840 open die forging parts and seamless rolled steel forged rings. With an 80,000 ㎡ production workshop, 120,000 tons annual manufacturing capacity, and 25+ years of forging experience, we provide one-stop custom forging from EAF+VD steel melting, forging, heat treatment, to precision CNC machining — fully in accordance with international standards, your custom drawings and technical manuals.
We use Electrical Furnace Melting + Full Vacuum Degassing (EAF+VD) technology to melt all AISI 9840 forged parts, in this way they can get the highest internal purity, chemical uniformity, ultra-low gas content, and work stably to meet the strictest requirements of heavy-duty industrial uses across North America, Europe, Australia, Southeast Asia, the Middle East, and 50+ countries worldwide.
Why is Jiangsu Liangyi for AISI 9840 Forging Parts?
ISO 9001:2015 Certified Since 1997
More than 25 years of certified forging experience. Our quality management system is audited and verified in accordance with international standards and is trusted by buyers from over 50+ countries.
EAF+VD Melting — Best Purity
All AISI 9840 steel is melted via Electrical Furnace + Full Vacuum Degassing (EAF+VD), in this way each forging part will get ultra-low impurity, minimal gas content, and consistent alloy chemistry.
100% UT Testing + Full MTC
We do 100% ultrasonic non-destructive testing (UT) on each AISI 9840 forging part for internal defects, plus surface crack detection (MT/PT). We will offer EN 10204 3.1 MTC for each part.
One-Stop Service From Melting to Machining
We will do all forging in house: steel melting → forging → heat treatment → precision CNC machining → inspection. You receive finished parts which are ready to be assembled.
30 KG to 30,000 KG — Any Size
Bars up to Ø1200mm × 12m, seamless rings up to OD 5m, open die forgings from 30 to 30,000 KGS per piece. All custom sizes per your drawings — no size is too large or complex.
Global Export to 50+ Countries
We have rich experience in preparing shipping documents, INCOTERMS, customs clearance and are familiar with the shipping logistics to the USA, UK, Germany, India, Australia, UAE, and 50+ countries.
Lead Time — 15 to 45 Days
The lead time for standard forged bars and rings is 15–25 days while the lead time for full custom parts is 30–45 days. We will speed up the production for urgent orders.
Custom Solutions — Per Your Drawings
We manufacture forging parts as per your drawings, technique manuals, and industrial requirements. Any shape, any size, any heat treatment way is OK for us. Our engineers provide technical support from quotation to delivery.
AISI 9840 Forged Steel Products We Supply
Thanks to the advanced forging equipmentforging equipment and 25+ years of manufacturing experience, we can produce custom AISI 9840 (AMS 6342, UNS G98400, SAE 9840) forged steel parts in any shape and size. The weight for single piece ranges from 30 KGS to 30,000 KGS. All products are fully in accordance with ASTM, AMS, DIN, EN, JIS international standards and customer's drawings. Our main products include the following:
① AISI 9840 Forged Bars, Billets & Solid Rods
We supply precision forged AISI 9840 round bars, square bars, flat bars, rectangular bars, billets, and solid rods with full custom sizes, heat treatment states, and machining precision. No matter raw material forged bars for further machining or finished forging parts, both are OK for us.
② AISI 9840 Seamless Rolled Rings & Forged Rings
Our AISI 9840 forging rings include seamless rolled rings, forged rings, riding gear rings, slewing bearing ball races, flanges, and custom ring-shaped forgings, with outer diameter up to 5 meters. We also can produce contoured rolled rings and special-shaped rings per your drawings which are used in large rotating equipment and heavy-duty machinery.
③ AMS 6342 Forged Shafts, Gear Wheels & Pinion Parts
We can make AISI 9840 gear shafts, pinion shafts, spindles, step shafts, spline shafts, crankshafts, eccentric shafts, rotor shafts, gear wheels and pinions that are accordance with AMS 6342 standard. We can also machine the parts to the size per your drawings.
④ UNS G98400 Forged Sleeves, Hubs & Hollow Parts
We supply UNS G98400 forged hubs, housings, shells, sleeves, bushes, bushings, casings, hollow bars, seamless pipes, tubes, barrels, and other thick-walled hollow parts. Inner and outer diameters, wall thickness, length, and precision machining requirements all meet your industry needs exactly.
⑤ SAE 9840 Forged Discs, Blocks, Plates & Custom Open Die Forgings
We also provide SAE 9840 forged discs, blocks, plates, valve bodies, flanges, cylinders, wheels, and any custom-shaped open die forgings. With strict control of flatness, size tolerance, internal quality, and material uniformity, our products are for structural and heavy equipment uses across all major industries.
Check our full range of forged steel products and forging material grades for your project.
AISI 9840 Forging Parts — Industry Uses & Global Case Studies
Thanks to its good mechanical properties, AISI 9840 (AMS 6342, UNS G98400, SAE 9840) forged parts are widely used in heavy-duty industries which requires high strength, great toughness, wear resistance, and long-term performance under bad loads, impact, and hard working conditions. Below are our main cases:
🌬️ Renewable Energy — Wind Power & Hydropower
AISI 9840 steel is one of the best materials for main load-bearing parts in renewable energy equipment. AISI 9840 precision forged gear shafts, ring gears, planet gears, main shafts of wind turbine gearboxes, turbine shafts and rotor shafts of hydropower station generators can be produced. The material has good fatigue resistance and impact toughness for long-term stable service under variable loads and harsh outdoor conditions.
⛏️ Mining & Heavy Engineering Machinery
We supply custom AISI 9840 forged shafts for gyratory crushers and jaw crushers, main spindles for mining excavators, slewing bearing ball races, belt pulley wheels, and crusher hammer shafts for heavy-duty mining and engineering equipment. We also supply forged crane wheels, track wheels, hydraulic cylinder parts and other parts working in severe abrasive and impact environments.
🏭 Metallurgy, Cement & Sugar Mill Industry
We provide AISI 9840 shell hardening grinding pinion shafts for cement mill rotary kilns, gear shafts, pinion shafts, roller shafts for sugar mills, as well as seat wheel rings, support rollers, and ring gears for granulators, rotary dryers, coaters, and coolers. We also supply forged pull torque rods and other main rotating parts for continuous heavy industrial production lines.
🚂 Railway & Transportation Power Transmission
AISI 9840 is the best material for high-load transmission parts in the transportation industry. We produce forged drive shafts for heavy-duty trucks and engineering vehicles, traction motor shafts, automotive ring gears, planetary gears, pinion shafts, as well as forged crankshafts for gas compressors, mechanical presses, and high-pressure pumps.
🛢️ Oil & Gas and Offshore Engineering
For oil and gas exploration, drilling, and offshore engineering projects, we manufacture UNS G98400 forged gear shafts and pinion shafts for oil drilling tools, herringbone gear shafts for drilling rig mud pumps, and high-strength thread tie rods for offshore engineering projects. We also supply forged stub shafts, spindles and seamless rolled rings for marine and offshore systems.
🌿 Environmental Protection & General Industrial Equipment
We also supply custom AISI 9840 forged parts for environmental protection equipment, including high-precision atomizer shafts for flue gas desulfurization (FGD) scrubber systems. We also provide forged conveyor pulley shafts, cold mill decoiler and coiler mandrel drum shafts, gear couplings, hydraulic cylinder parts, and various custom forged parts for special industrial equipment.
AISI 9840 Same Grades of Steel— DIN, EN, JIS, GB, BS Standards
One of the most frequently asked questions by our buyers is: "What kind of steel is similar to AISI 9840 steel in European / German / Japanese / Chinese standards?" The following table lists the steels of the same grades with AISI 9840 (AMS 6342 / UNS G98400 / SAE 9840) as per all major standards. Their compositions are almost the same, so be sure to verify the exact chemical composition with your engineering team.
| Standard / Country | Designation | Grade / Material No. | Notes |
|---|---|---|---|
| AISI / SAE (USA) | AISI / SAE | 9840 | Exact Name |
| AMS (Aerospace) | AMS 6342 | UNS G98400 | SAE Aerospace Spec. |
| EN / DIN (Europe / Germany) | EN 10083-3 | 36NiCrMo4 / 1.6511 | Close Ni-Cr-Mo equivalent |
| ISO (International) | ISO 683-1 | 36NiCrMo4 | Near equivalent |
| JIS (Japan) | JIS G4053 | SNCM439 / SNCM447 | Closest Japanese equivalent |
| GB / YB (China) | GB/T 3077 | 40CrNiMo | Closest Chinese equivalent |
| BS (UK) | BS 970 | 905M39 / 830M31 | Obsolete BS, now EN 10083 |
| SS (Sweden) | SS 142541 | 2541 | Near equivalent |
| AFNOR (France) | NF A35-552 | 35NCD4 | Close equivalent |
| GOST (Russia) | GOST 4543 | 40XHM | Near equivalent |
Important Note: While the above grades are the closest international equivalents to AISI 9840, exact chemical compositions vary between standards. Jiangsu Liangyi can manufacture forgings to any of these international standards upon request, with full documentation and mill test certifications. Contact us for free material grade consultation.
Chemical Composition of AISI 9840 Steel (AMS 6342 / UNS G98400 / SAE 9840)
We strictly control the chemical composition of each AISI 9840 forged steel heat batch, the composition is fully traceable and reported in the EN 10204 3.1 mill test certification. The standard chemical composition that are in accordance with AISI, SAE, AMS, and UNS international standards is as follows:
| Chemical Element | Symbol | Standard Content Range (Weight %) |
|---|---|---|
| Carbon | C | 0.38 – 0.43 % |
| Nickel | Ni | 0.85 – 1.15 % |
| Chromium | Cr | 0.70 – 0.90 % |
| Molybdenum | Mo | 0.20 – 0.30 % |
| Manganese | Mn | 0.70 – 0.90 % |
| Silicon | Si | 0.15 – 0.30 % |
| Phosphorus (max) | P | ≤ 0.035 % |
| Sulfur (max) | S | ≤ 0.040 % |
| Iron (Balance) | Fe | 95.945 – 97.02 % (Balance) |
Note: Chemical analysis including unstable elements (Cu, Sn, As, Sb, Pb) is reported in each EN 10204 3.1 mill test certificate. Ladle and product analysis are both made for each heat batch.
AISI 9840 vs AISI 4340 — Main Differences & When to Choose 9840
Buyers frequently compare AISI 9840 with AISI 4340 when choosing alloy steel for different industries. They are both Ni-Cr-Mo steels with good hardenability and toughness, but AISI 9840 has advantages in specification. The main differences are as followings:
| Property | AISI 9840 (AMS 6342) | AISI 4340 (AMS 6415) |
|---|---|---|
| Nickel Content | 0.85 – 1.15 % | 1.65 – 2.00 % |
| Chromium Content | 0.70 – 0.90 % | 0.70 – 0.90 % |
| Molybdenum Content | 0.20 – 0.30 % | 0.20 – 0.30 % |
| Manganese Content | 0.70 – 0.90 % | 0.60 – 0.80 % |
| Tensile Strength (Q&T) | ~1240 MPa | ~1275 MPa |
| Yield Strength (Q&T) | ~1105 MPa | ~1170 MPa |
| Relative Material Cost | ✅ Lower (less Ni) | Higher (more Ni) |
| AMS Aerospace Standard | AMS 6342 | AMS 6415 |
| UNS Designation | UNS G98400 | UNS G43400 |
| Availability in China | ✅ Readily Available | ✅ Readily Available |
| Best For | Cost-sensitive heavy-duty uses, comparable strength to 4340 | Ultra-critical aerospace, highest toughness uses |
Recommendation: For most heavy industrial uses — mining, cement mill, wind energy, marine, railway — AISI 9840 offers the same mechanical properties as 4340 but at a more competitive material cost. If your uses require the absolute highest nickel content toughness or specific AMS 6415 certification, we also supply AISI 4340 forging parts. Contact our engineers for material selection support.
Mechanical Properties of AISI 9840 Forged Steel (After Quenching & Tempering)
After standard quenching and tempering (Q&T) heat treatment, our AISI 9840 forged steel has stable and good mechanical properties that fully meet the design requirements of different heavy-duty industrial uses. Main properties of heat-treated AISI 9840 (AMS 6342) forgings are as follows:
| Mechanical Property | Test Method | Typical Value |
|---|---|---|
| Ultimate Tensile Strength (UTS) | ASTM E8 / ISO 6892 | 1240 MPa (180 ksi) |
| Yield Strength (0.2% Offset) | ASTM E8 / ISO 6892 | 1105 MPa (160 ksi) |
| Elongation at Break | ASTM E8 / ISO 6892 | 15 % |
| Reduction of Area | ASTM E8 / ISO 6892 | 55 % (typical) |
| Charpy V-Notch Impact (CVN) | ASTM E23 / ISO 148 | ≥ 34 J at RT (typical) |
| Hardness (After Q&T) | ASTM E10 / Brinell (HBW) | Custom per requirements |
| Modulus of Elasticity | — | ~200 GPa |
We can fully custom a heat treatment way to get your specific mechanical property and hardness targets. Our professional engineers can give advise on heat treatment way based on your uses and working conditions.
Quality Control for AISI 9840 Forged Parts — ISO 9001:2015 Certified
Quality is the most important in our business. Our QC department will do inspection on all AISI 9840 (AMS 6342, UNS G98400, SAE 9840) forged part to make sure every product fully meets your specifications, drawings and international quality standards. Our inspection and testing includes the below:
- 100% Visual Examination — External surface inspection for cracks, laps, seams, and surface defects
- Full Size Inspection — 100% size inspection per drawing, with tolerance report
- Chemical Composition Analysis — Spectrometric analysis for every heat batch (ladle + product analysis)
- Mechanical Properties Testing — Tensile strength, yield strength, elongation, reduction of area, Charpy impact
- Hardness Testing — Brinell or Rockwell hardness test per drawing
- Macrostructure & Microstructure test — Macro etch test and metallographic analysis
- 100% Ultrasonic Testing (UT) — 100% volumetric ultrasonic inspection per ASTM A388 / EN 10228-3/-4 for internal defects
- Magnetic Particle Testing (MT) or Liquid Penetrant Testing (PT) — 100% surface crack detection per ASTM E709 / EN 10228-1/-2
- Residual Stress Test — Upon request for critical parts
All production are strictly accordance with the ISO 9001:2015 quality management system. We provide EN 10204 3.1(or 3.2 on request) mill test certifications (MTC) for each order which show all the above inspection results for full traceability.
Test Certification — EN 10204 3.1 MTC
We provide mill test certification for each batch of AISI 9840 forged parts for your projects. EN 10204 3.1 MTC includes the following:
- Heat number, melting type (EAF+VD), and full material grade identification
- Full size inspection results and tolerance check report
- Full heat treatment cycle details (quenching temperature, tempering temperature, holding times, cooling media)
- Full chemical analysis results including all alloy elements and unstable elements
- Complete mechanical test results (UTS, YS, elongation, reduction of area, Charpy impact, hardness) — all individual test results reported
- 100% Ultrasonic Testing (UT) results per relevant standard
- Surface crack detection (MT/PT) results per relevant standard
- Visual inspection and size check confirmation signatures
- Results of any additional tests specified in your drawing or purchase order
- Third-party inspection reports (BV, SGS, Lloyd's, TÜV, etc.) upon request
Global Supply — AISI 9840 Forging Parts for Buyers Worldwide
We supply custom AISI 9840 (AMS 6342, UNS G98400, SAE 9840) forging parts to buyers in more than 50 countries. We have rich experience in preparing international shipping documentation, Incoterms, customs requirements, and international logistics arrangements. Below are some major markets but not limited:
No matter you are a procurement manager sourcing AISI 9840 forged parts for a project in the USA, a purchasing engineer in Germany looking for AMS 6342 accordance gear shafts, an equipment manufacture in India needing custom seamless rolled rings, or a maintenance team in Australia requiring replacement forged shafts — Jiangsu Liangyi will be your best partner.Contact us for a free quote for your specific requirements.
Frequently Asked Questions (FAQ) — AISI 9840 Forging Parts
The main difference between AISI 9840 and AISI 4340 is that AISI 9840 has a higher manganese content and a lower nickel content (0.85–1.15%) compared with AISI 4340 (1.65–2.00%). This gives AISI 9840 a more balanced combination of strength, toughness, and cost-effectiveness, making it a popular and more economical alternative to 4340 for many heavy-duty industries.
There are many standards for AISI 9840 steel: AISI 9840, SAE 9840, AMS 6342 (SAE Aerospace Material Specification), and UNS G98400 (Unified Numbering System). And we can also meet DIN, EN, JIS, and other regional standards on request.
Yes. We have 10 professional heat treatment furnaces and provide fully custom heat treatment way for AISI 9840 forgings, including quenching, tempering, normalizing, annealing, case hardening, and stress relieving. We custom heat treatment way precisely to meet your required hardness, tensile strength, yield strength, and toughness requirements.
Forged bars and shafts: maximum length 12 meters, diameter range Ø50mm–Ø1200mm. Seamless rolled rings: maximum outer diameter 5 meters. Open die forgings: single piece weight from 30 KGS to 30,000 KGS. All custom sizes and shapes can be manufactured per your drawings.
Yes. We provide a one-stop service from steel melting, forging, heat treatment to precision CNC machining — rough machining, semi-finish machining, and finish machining to your drawing requirements, with small size tolerance. You will receive the finished parts ready for assembly. This will save your production time and reduce the total supply chain cost.
AISI 9840 forging parts are widely used in below industries: wind energy and hydropower, mining and engineering machinery, cement and sugar mills, oil and gas and offshore engineering, railway and heavy truck transportation, marine and shipbuilding, industrial gearboxes and gear reducers, environmental protection equipment, and general heavy machinery manufacturing.
The lead time for normal forged bars and rings is 15–25 working days while 30–45 working days for custom parts with precision CNC machining. We can also arrange the production in advance for urgent orders — please tell your timeline when you send the inquiry.
Yes. We can provide mill test certification (MTC) per EN 10204 3.1. MTC will record the results of chemical composition analysis, mechanical test, heat treatment way, UT and surface inspection, as well as other traceable information. If necessary, we can also offer EN 10204 3.2 certifications and inspection reports from third-parties like SGS, BV, Lloyd's, and TÜV.
All our AISI 9840 forged parts use Electrical Furnace Melting + Full Vacuum Degassing (EAF+VD) technology. This advanced two-stage melting method makes our forging parts get internal purity, minimal hydrogen and nitrogen content, uniform alloy chemistry, and work consistently well — meeting the strictest requirements of heavy-duty industries.
We supply AISI 9840 forging parts to 50+ countries, including the USA, UK, Germany, Australia, Canada, India, Singapore, UAE, Saudi Arabia, South Africa, Netherlands, France, Poland, Italy, Spain, Malaysia, Vietnam, Thailand, Brazil, and Mexico. We are familiar with export documentation, international shipping, INCOTERMS, and region-specific quality requirements.
How to Order Custom AISI 9840 Forging Parts — 5 Simple Steps
It is easy and fast to order custom AISI 9840 (AMS 6342, UNS G98400, SAE 9840) forging parts from Jiangsu Liangyi. Our sales and engineering team will help you step by step, from inquiry to final delivery:
📧 Send Your Drawing or Requirement
Send your drawing (PDF, DWG, STEP or similar) or written requirement — including material grade (AISI 9840 / AMS 6342 / UNS G98400), sizes, weight, heat treatment way, and quantity — to [email protected] or via WhatsApp +86-13585067993.
💬 Get A Free Quote Within 24 Hours
We will check your drawing and technique manuals, then send you a quotation within 24 hours (working days), along with necessary information such as prices, materials, machining, heat treatment ways, inspection, packaging and delivery time.
✍️ Send Us The Order & Pay The Deposit
Please send us the order and pay the deposit. We accept both T/T (Bank Transfer) and L/C (Letter of Credit). We will arrange the production immediately upon receipt of the deposit.
🏭 Production & Full Quality Inspection
We manufacture your AISI 9840 forgings all in house: EAF+VD melting → forging → heat treatment → precision CNC machining → 100% UT volumetric inspection → surface crack detection → size check → EN 10204 3.1 MTC preparation. We can also provide an inspection report from a third-party like SGS, BV, TÜV, or Lloyd's upon request.
🚢 Shipment & Document
We pack the parts in wood and book shipping (FOB Jiangyin, CIF, or DDP as agreed).We also provide a full set of documents such as Commercial Invoice, Packing List, Bill of Lading, EN 10204 3.1 MTC, Inspection reports, Certificate of Origin, and any other certification required.
Good Track Record — Why do Buyers Trust Jiangsu Liangyi
Since 1997, Jiangsu Liangyi has earned a good reputation with consistent quality, professional technology and good delivery. The following data show our capabilities as an ISO 9001:2015 certified forging manufacturer:
(Est. 1997)
Countries
Capacity
Workshop Area
30,000KG Single Piece
Weight Range
Furnaces
Certification, Quality Standards & Third-Party Inspection
- ISO 9001:2015 Quality Certificated— Independent audit and certificate. Certification will be provided upon request.
- EN 10204 3.1 Mill Test Certificate (MTC) — We will provide certifications for each batch of parts, including chemical analysis, mechanical test results, heat treatment records and UT inspection results. All data are traceable.
- Third-Party Inspection Support — We accept inspection by a third-party including SGS, Bureau Veritas (BV), Lloyd's Register, TÜV, RINA or others. Buyers may appoint their own inspector at any time.
- EN 10204 3.2 Certifications — We can also provide upon request.
- EAF+VD (Electrical Furnace + Vacuum Degassing) Melting — Full traceability from heat number to finished forging is recorded in every MTC.
- 100% Ultrasonic Testing (UT) — All forgings are tested per ASTM A388 / EN 10228-3/4.
📋 Project References & Case Studies
We have supplied AISI 9840 forging parts to buyers across 50+ countries for 25+ years. We are happy to provide project references, sample MTC documents, and relevant case studies upon request — please contact us directly.
View Project References & Case Studies → | Request References Directly →
| Published by: Jiangsu Liangyi Co.,Limited — ISO 9001:2015 Certified China Forging Manufacturer | www.jnmtforgedparts.com
Request a Free Quote for Custom AISI 9840 Forging Parts
Jiangsu Liangyi is a professional ISO 9001:2015 certified AISI 9840 forging parts manufacturer and supplier in China. We have over 25 years of experience in custom open die forging and seamless rolled ring production. And We have supplied high-quality AISI 9840 (AMS 6342, UNS G98400, SAE 9840) forged parts to buyers in more than 50 countries.
Whether you need raw material forged bars, precision seamless rolled rings, custom gear shafts, or finished CNC machined parts — we provide a one-stop solution according to your drawings and specific requirements.
Send us your drawing or specifications today for a fast, free, no-obligation quotation with full technical support from our experienced engineering team.
📧 Email: [email protected] | 📞 Phone/WhatsApp: +86-13585067993 (Click to WhatsApp Chat)
📩 Send Your Custom Inquiry Now — Free Quote