AISI 4145 Forging Parts
SAE 4145H | AISI 4145H MOD | Open Die Forgings & Seamless Rolled Rings
Jiangsu Liangyi Co., Limited | ISO 9001:2015 & API 6A Certified | Est. 1997
⚡ AISI 4145 Forging Parts – Basic Information
- Material: AISI 4145 / SAE 4145H / AISI 4145H MOD – Chromium-Molybdenum (Cr-Mo) low-alloy steel
- Carbon Content: 0.42–0.49% (higher than 4140, offering good wear resistance)
- Yield Strength: ≥ 110–125 ksi (758–862 MPa) after Q&T heat treatment
- Hardness: 285–341 BHN (surface, after final quench & temper)
- Charpy Impact: ≥ 20 ft-lbs at -40°F (longitudinal CVN)
- Standards: ASTM A29, AISI, SAE, API 6A, DIN, EN
- Main Uses: Oil & gas downhole tools, mining drill parts, gear transmission, valve & pump bodies
- Certifications: ISO 9001:2015, API 6A, ISO 17025 certified laboratory
- Manufacturer: Jiangsu Liangyi Co.,Limited – Jiangyin, Jiangsu, China (Est. 1997)
- Capacity: 30 KGS to 30,000 KGS per piece, 120,000 tons annual capacity
What is AISI 4145 / 4145H / 4145H MOD Forged Steel?
AISI 4145 is a premium chromium-molybdenum (Cr-Mo) low-alloy quenched and tempered (QT) steel. It is a good choice for heavy industrial uses because of its good hardenability .It is most commonly used under high-strength conditions with a minimum yield strength of 125 ksi / 110 ksi, and it has good toughness, wear resistance, and fatigue performance under extreme dynamic and static loads.
AISI 4145H is an improved hardenability grade in this steel series.It is specially designed for downhole drilling tools, heavy engineering parts and wear-resistant machine parts that require consistent through-hardening even in thick cross-sections.Jiangsu Liangyi is a professional Chinese manufacturer of open die forgings and seamless rolled steel rings which are made from AISI 4145, SAE 4145H, AISI 4145H MOD and modified AISI 4145H.We serve industrial customers in more than 50 countries.
Our in-house metallurgical team, supported by an ISO 17025-certified laboratory, can customize AISI 4145H MOD steel.
Custom AISI 4145 Forging Products & Shapes We Supply
We can make forged AISI 4145 products in many different shapes and sizes according to your drawings and technical manual. We make all types of open die forgings and seamless rolled rings as below but not limited:
AISI 4145 Forged Bars & Shafts
Precision forged round bars, square bars, flat bars, rectangular bars, solid rods, step shafts, gear shafts, splined shafts, and crankshafts for general engineering and heavy-load transmission uses. All bars are forged with a minimum 5:1 reduction ratio to ensure optimal internal grain structure and mechanical performance.
SAE 4145H Seamless Rolled Forged Rings
Custom seamless rolled rings, actuator rings, well casing swivel rings, riser flanges, swivel ring flanges, gear rings, bearing races, and contoured rolled rings for oil and gas, industrial, and power generation uses. Produced on our 1–5 meter CNC seamless rolling machines.
AISI 4145H MOD Forged Hollow Parts
Heavy-duty forged hubs, housings, shells, sleeves, bushes, casings, hollow bars, pipes, tubing, barrels, drill head casings, and collars for downhole drilling, wellhead, and subsea uses. All hollow parts undergo 100% full-volume ultrasonic inspection per ASTM A388 standards.
AISI 4145 Custom Forged Special Parts
Fully custom forged discs, blocks, plates, valve parts, pump parts, gear transmission parts, flanges, cylinders, and fully machined forgings manufactured to your exact engineering drawings. We support custom material grades with custom heat treatment available for all parts.
Industry Uses & Global Cases
AISI 4145 forged parts are used in the strictest industrial fields, including oil and gas, mining, gear drives, fluid control, power generation, shipbuilding and aerospace where high strength, wear resistance and fatigue performance are needed.
Oil & Gas Downhole & Wellhead Uses (North America & Middle East)
Our AISI 4145 series forgings are the best material for onshore and offshore oil and gas operators in North America and the Middle East, in full accordance with API 6A industry standards. They are used on many downhole drilling tools, including drill collars, drill pipes, mud motor spline drive shafts, ESP motor spline shafts, wellhead Christmas tree parts, casing heads, tubing heads, casing hangers, blowout preventer (BOP) bodies, fracturing pump fluid end blocks, and high-pressure subsea parts.
Case 1: High-Pressure Shale Gas Fracturing Project (Permian Basin, USA & Saudi Arabia, 2023)
We have successfully used our AISI 4145H MOD forged Christmas tree wellhead bodies, fracturing heads, and double-stud adapter flanges in high-pressure shale gas projects in the Permian Basin (USA) and onshore oilfields in Saudi Arabia. These parts are made with a minimum forging reduction ratio of 5:1, and quenched and tempered to get a minimum yield strength of 110 ksi, enabling them to withstand extreme downhole pressures over 10,000 psi.We have delivered more than 2,000 sets of these critical parts for over 200 oil and gas wells, reducing equipment maintenance frequency by 40%.
Mining & Raise Boring Drilling Uses (Australia & South America)
We supply SAE 4145H and AISI 4145H Modified forged parts for large-scale hard rock mining companies in Australia and South America, and they fully meet AS/NZS standards. Our products include raise boring machine drill stabilizers, drill stems, stabilizer roller reamer bodies, raise boring machine spare parts, and heavy-duty drilling parts.
Case 2: Hard Rock Mining Raise Boring Project (Western Australia & Chile, 2023)
SAE 4145H forged stabilizer roller reamer bodies, drill collars, and raise boring machine drill rods have been supplied to major metal mining raise boring projects in Western Australia and Chile.These parts have great wear and torque resistance after ultrasonic inspection per ASTM A388. We have delivered over 5,000 sets of core drilling parts, with a service life three times longer than standard carbon steel parts.
Gear Transmission & Offshore Engineering Uses (Europe & Southeast Asia)
AISI 4145 forged parts are used in heavy-duty gear transmission systems all over Europe and Southeast Asia. They all meet CE and EN standards and are always used in gearbox housings, gear reducers, gear wheels, pinion shafts, ring gears and gear shafts
Case 3: Offshore Jack-Up Platform Gear Transmission Project (North Sea & Singapore, 2022)
AISI 4145 forged gearbox gears, pinion shafts, and ring gears are used in lifting equipment, gear reducers, and offshore jack-up platform gear transmission systems in the North Sea and Southeast Asia. After Q&T, the parts get a surface hardness of 285–341 BHN. We have supplied over 10,000 sets with an operating failure rate of less than 0.2%.
Fluid Control, Pump & Valve Parts (North America & Europe)
Our AISI 4145 forgings are widely used for industrial valve and pump parts in petrochemical, water treatment and power generation projects across North America and Europe. They are always used in valve balls, bonnets, valve bodies, valve stems, seat rings, gate valves, check valves, mud pump and fracturing pump parts, pump casings, impellers, pump shafts and flow meter bodies.
Case 4: High-Pressure Petrochemical Fluid Control Project (Germany & USA, 2024)
AISI 4145H forged ball valve bodies, valve stems, seat rings, and gate valve bodies are used in high-pressure fluid control systems in petrochemical projects in Germany and the Gulf Coast (USA). All parts go through strict non-destructive testing to make sure they can meet ASTM standards, . We have made custom forged valve parts for more than 300 industrial fluid projects.
AISI 4145H Chemical Composition & Metallurgical Specifications
The chemical composition of our AISI 4145H Modified material is strictly controlled to meet ASTM A29 international standards.AISI 4145 steel is a fine-grained aluminum-killed steel, melted in an electric arc furnace (EAF), then refined by ladle furnace (LF) treatment and vacuum degassing (VD).
| Element | AISI 4145 (wt.%) | SAE 4145H (wt.%) | AISI 4145H MOD (wt.%) | Role / Effect |
|---|---|---|---|---|
| Carbon (C) | 0.43 – 0.48 | 0.42 – 0.49 | 0.42 – 0.49 | Controls hardness & tensile strength |
| Manganese (Mn) | 0.75 – 1.00 | 0.95 – 1.30 | 1.00 – 1.50 | Improves hardenability & strength |
| Chromium (Cr) | 0.80 – 1.10 | 0.75 – 1.20 | 1.00 – 1.30 | Wear & corrosion resistance |
| Molybdenum (Mo) | 0.15 – 0.25 | 0.15 – 0.25 | 0.15 – 0.25 | High-temperature strength & hardenability |
| Silicon (Si) | 0.15 – 0.35 | 0.15 – 0.35 | 0.15 – 0.35 | Deoxidizer, grain refinement |
| Phosphorus (P) | ≤ 0.035 | ≤ 0.035 | ≤ 0.025 | Controlled for toughness & ductility |
| Sulfur (S) | ≤ 0.040 | ≤ 0.040 | ≤ 0.010 | Controlled for inclusion cleanliness |
| Aluminum (Al) | 0.020 – 0.050 | 0.020 – 0.050 | 0.020 – 0.050 | Grain refinement (Al-killed steel) |
Note: Compared with standard 4145H, AISI 4145H MOD has stricter limits on phosphorus and sulfur, as well as optimized manganese and chromium contents. This has higher toughness and cleanliness for critical downhole and wellhead uses. All parts meet the requirements of ASTM A29.
Material Cleanliness & Inclusion Control
Inclusion content meets or exceeds the requirements of 3 heavy sulfide type, 3 heavy alumina type, 3 heavy silica type, and 4 heavy oxide type, per Jernkontoret (JK) Chart E45 (ASTM) Plate 1.
Forging Reduction Ratio
All AISI 4145H MOD forgings are press forged from a minimum 35-inch ingot size, with a minimum forging reduction ratio of 5:1 to break down the cast structure, refine grain size, delete internal porosity, and make sure optimal internal structure throughout the entire cross-section.
Grain Size Control
Grain size of all finished forged bars meets ASTM 5 or finer, as determined by ASTM E112 standard, make sure consistent strength, toughness, and fatigue resistance across the entire part, even in thick sections up to 500mm in diameter.
Heat Treatment Methods for AISI 4145 Forgings
All AISI 4145 forgings undergo strict, controlled heat treatment to get the specified mechanical properties, with full traceability for every heat lot. Our in-house heat treatment facility has ten computer-controlled industrial furnaces.
Preliminary Heat Treatment
All forgings undergo normalization and tempering to a maximum hardness of 300 BHN before rough machining. Normalization is performed at 870–900°C, followed by air cooling, with subsequent tempering at 600–650°C to get the required pre-machining hardness.
Final Heat Treatment
all finished forgings have the right mechanical properties and hardness range after quenching and tempering (Q&T) . Quenching is performed in water or polymer solution after austenitizing at 840–870°C, followed by tempering at 580–650°C to get the target mechanical properties.
Mechanical Properties & Testing Standards
All AISI 4145 forgings meet strict mechanical property requirements. All tests are conducted in our own ISO 17025-certified laboratory in accordance with international ASTM standards. We provide a full set of test reports (MTR 3.1/3.2) for each shipment.
| Mechanical Property | Minimum/Required Value | Test Method Standard |
|---|---|---|
| Surface Hardness (BHN) | 285 – 341 | ASTM E10 |
| Ultimate Tensile Strength | 135 ksi (931 MPa) | ASTM E8 |
| Yield Strength (0.2% Offset, Min.) | 110 ksi / 125 ksi | ASTM E8 |
| Elongation in 2" (Min.) | 15% | ASTM E8 |
| Reduction of Area (Min.) | 40% | ASTM E8 |
| Charpy V-Notch Impact (Longitudinal, Min.) | 20 ft-lbs @ -40°F | ASTM E23 |
Mandatory Testing Requirements
- Tensile tests: Longitudinal specimens, taken 2" below the surface or mid-radius (whichever is closer to the surface), with 1 test per 10 bodies per heat per heat treat lot.
- Impact tests: Charpy V-notch specimens with longitudinal and radial notches, taken 2" below the surface or mid-radius, with one test for every 10 bodies per heat per heat treat lot.
- Testing for hardness: BHN hardness was tested 2 inches below the surface or mid-radius, and every part was checked for 100% surface hardness.
- Each test value must meet or exceed the requirements, not just the average.
AISI 4145 vs SAE 4145H vs AISI 4145H MOD – Grade Comparison
Understanding the differences between AISI 4145, SAE 4145H, and AISI 4145H MOD is important for engineers when choosing the right material for their applications.
| Parameter | AISI 4145 | SAE 4145H | AISI 4145H MOD |
|---|---|---|---|
| Hardenability Control | Standard | Modified (tighter) | Custom-engineered (strictest) |
| Carbon Content (wt.%) | 0.43 – 0.48% | 0.42 – 0.49% | 0.42 – 0.49% |
| Sulfur Limit (wt.%) | ≤ 0.040% | ≤ 0.040% | ≤ 0.010% (extra clean) |
| Yield Strength (Min.) | 110 ksi | 110 – 125 ksi | Custom (typically ≥ 125 ksi) |
| Hardness (BHN, after Q&T) | 270 – 330 | 285 – 341 | 285 – 341 (customizable) |
| Through-Hardening | Good | Excellent | Superior (even at 500mm dia.) |
| Inclusion Cleanliness | Standard | Standard | JK Chart E45 – premium |
| Primary Application | General engineering, gear transmission | Downhole tools, heavy components | API wellheads, frac equipment, BOP |
| Applicable Standard | ASTM A29, AISI/SAE | ASTM A29, SAE J1268 | ASTM A29, API 6A, custom spec |
Non-Destructive Examination & Strict Quality Control
All heat-treated AISI 4145H forged parts undergo 100% non-destructive testing (NDT) in our in-house inspection facility, ensuring zero defects in critical parts. We do full quality control at every stage from steel melting to final machining, with full traceability for every part.
All finished parts undergo ultrasonic testing according to ASTM A388 standard,and they also undergo magnetic particle inspection (MPI), liquid penetrant inspection (LPI), and radiographic testing (RT) according to customer specifications.
Size & Surface Quality Control
- Straightness: We use CNC coordinate measuring machines (CMM) to check all the sizes to make sure that they are within the size tolerance. The maximum difference from a straight line is 1/8 inch over a length of 5 feet.
- Surface Finish: The vendor usually rough turns the outside surface to 250 RMS, but they can also do custom precision machining and surface finishing according to customer's requirement.
- Surface Imperfections: If they don't go deeper than 0.150", they're fine, but all defects must be fully recorded, fixed (if necessary), and approved by the customer before delivery.
Marking & Certification
Each finished forging is hard stenciled with Heat Number, Bar Number, Ingot Location, PO Number, and material grade for full traceability. We will give clients the certified test reports (MTR 3.1/3.2 EN 10204) for each shipment, including original mill certificates, heat treatment records, chemical composition, mechanical properties, hardness test results and non-destructive testing results.
Lead Time, Packing & Shipping for AISI 4145 Forging Parts
We are a direct forging manufacturer with all the tools we need to make steel and do final machining. We offer good lead times and reliable global shipping to our clients.
Production Lead Time
- Standard orders: 4–8 weeks after everything is approved, including raw steel procurement, forging, heat treatment, NDT, rough machining and final inspection.
- Urgent / expedited orders: lead time can be shortened based on production plan. Please contact us with your required timeline
- Sample / trial orders: Single or small-batch forgings always take 3–5 weeks.
Export Packing Standards
- All forged parts are packed in export-grade wooden cases or steel frames with full anti-corrosion treatment: oil coating + VCI (vapor corrosion inhibitor) film wrapping + moisture-proof silica gel desiccant.
- Each product is clearly labeled with: heat number, part number, material grade, heat treatment condition, weight, sizes and PO number.
- Custom packaging is as per customer specifications or project requirements.
Shipping & Documentation
- Shipping methods: products are shipped by sea (FCL/LCL from Shanghai or Ningbo port), by air (to all major global airports), or by different express courier (DHL, FedEx, UPS).
- Export documents: Shipping documents include a commercial invoice, a packing list, a bill of lading or air waybill, a certificate of origin (CO/Form A), a material test report (MTR 3.1/3.2 EN 10204), inspection certificates, and a phytosanitary certificate for wooden packaging (ISPM 15 compliant).
- Trade terms: EXW, FOB Shanghai/Ningbo, CFR, CIF, DAP/DDP.
Get a Custom Quote for Your AISI 4145 Forging Parts
We provide custom forging solutions to your exact engineering drawings and project requirements, with strict ISO 9001 quality control, competitive pricing, and on-time delivery for global clients. Contact us today to discuss your project!
Request a Free Custom QuoteFrequently Asked Questions (FAQ)
AISI 4145 is a premium chromium-molybdenum (Cr-Mo) low-alloy steel. It is used for forging parts that need high tensile strength, good toughness, and great wear resistance. It is always used in quenched and tempered (QT) condition, with a minimum yield strength of 110–125 ksi, making it an ideal material choice for heavy-duty industrial parts in oil & gas, mining, and heavy engineering industries.
The "H" in AISI 4145H stands for Hardenability Modification. 4145H has stricter chemical composition control and is specifically optimized to improve through-hardening performance, making it the best grade for heavy-duty downhole drilling tools, large forged parts, and high-pressure industrial uses.
AISI 4145H MOD (Modified) is a custom-engineered version of standard 4145H steel, and its chemical composition and mechanical properties can be adjusted to meet the specific requirements of different uses such as high-pressure oil and gas wellhead parts, downhole drilling tools, and heavy mining equipment.
AISI 4145 forging parts are mainly used in: oil and gas downhole drilling tools, wellhead equipment, and BOP parts; mining raise boring machine parts, drill rods, and stabilizers; heavy-load gear transmission systems, gearboxes, pinion shafts, and gear wheels; industrial valves, pumps, and fluid control parts; power generation turbine parts; and other heavy engineering machinery.
The usual surface hardness range of AISI 4145H steel is 285–341 BHN after quenching and tempering (Q&T) heat treatment, This hardness range can be fully customized based on your specific project requirements. Preliminary normalization and tempering before machining results in a maximum hardness of 300 BHN.
We support both one piece sample orders or big volume mass production orders. As a direct manufacturer with 120,000 tons annual capacity, we can make parts from 30 KGS to 30,000 KGS per piece.
Standard lead time is 4–8 weeks from order confirmation, depending on complexity, weight, quantity, and heat treatment. Rush orders may be accommodated. Delivery is via sea freight (FCL/LCL), air freight, or express courier.
Yes. We offer CNC machining services from turning, milling, drilling, boring, grinding, and thread cutting to deliver fully finished parts according to your exact drawing tolerances. Surface finish options range from rough turned (250 RMS) to precision ground (Ra 0.8 or better).
Yes. We fully support third-party inspection by Bureau Veritas (BV), SGS, Intertek, Lloyd's Register, and DNV-GL, as well as direct customer factory inspection. Certified material test reports (MTR 3.1/3.2 per EN 10204) are provided with every shipment.
All parts are packed in wooden cases or steel racks with full rust-prevention treatment (oil coating and moisture-proof film wrapping). The heat number, material grade, weight, and order number are all written on each piece. We handle all types of transportation around the world, including sea freight, air freight, and multimodal transport. We also provide all the necessary shipping documents.
Global Markets & Industries We Serve
Since 1997, Jiangsu Liangyi Co.,Limited has supplied AISI 4145 forged parts to customers across 50+ countries. Our forged parts are used in some of the most demanding operating environments.
North America (USA & Canada)
Downhole drilling tools, frac pump fluid end blocks, wellhead Christmas tree parts, and BOP bodies for shale gas and tight oil operations. Fully in accordance with API 6A and ASME standards.
Europe (Germany, UK, Netherlands)
Gear transmission parts, gearbox housings, pinion shafts, and offshore jack-up platform rack-and-pinion parts. In accordance with EN, DIN, and CE marking requirements.
Australia & New Zealand
Hard rock mining raise boring machine drill stems, stabilizer roller reamer bodies, and drill collars for underground mining operations. In accordance with AS/NZS standards.
Middle East (Saudi Arabia, UAE)
Onshore and offshore oil field wellhead parts, casing heads, tubing heads, casing hangers, and high-pressure valve bodies for national and international oil companies operating in the region.
South America (Chile, Brazil)
Forged parts for surface and underground mining equipment, raise boring machine parts, as well as heavy-duty drill pipes for copper, gold and iron ore mining projects.
Southeast Asia (Singapore, Malaysia)
Offshore platform gear transmission parts, marine engineering parts, pump and valve bodies for petrochemical refineries, and industrial machinery forgings.
Why Choose Jiangsu Liangyi as Your Global Forging Partner?
As a professional manufacturer of open die forging, Jiangsu Liangyi Co.,Limited is an ISO 9001:2015 and API 6A certified enterprise, We mainly produce custom AISI 4145 series forged parts. Our factory covers an area of 80,000 m² with fixed assets of USD 40 million and an annual manufacturing capacity of 120,000 tons, so we can handle forged parts from 30 KGS to 30,000 KGS with full production flexibility.
- ✅ 25+ years open die forging expertise since 1997
- ✅10 computer-controlled furnaces for full heat treatment in-house
- ✅ ISO 17025 certified laboratory – independent certified testing
- ✅ 1–5 meter CNC seamless ring rolling mills for precision seamless rings
- ✅ 50+ countries served: USA, Canada, Germany, UK, Australia, Saudi Arabia, UAE, Singapore, Chile, South Africa and more
- ✅ Third-party inspection friendly: BV, SGS, Intertek, Lloyd's, DNV-GL supported
- ✅ Full material traceability: heat number tracked from steel melt to finished product
- ✅ Custom chemical composition: AISI 4145H MOD tailored to your project spec
We offer complete in-house capabilities from primary steel melting, forging, heat treatment to precision machining and third-party inspection, ensuring strict quality control throughout the entire production process.
Contact Us For a Custom Forging Quotation
We are glad to provide the most competitive pricing and great quality forged steel materials for global industrial clients. Welcome to send your drawings, material requirements, and order quantity for a detailed, no-obligation quotation!
📧 Inquiry Email: [email protected]
📞 Phone/WhatsApp: +86-13585067993
☎ Tel: 0086-510-86107550
🌐 Website: https://www.jnmtforgedparts.com
📍 Address: Chengchang Industry Park, Jiangyin City, Jiangsu Province, China 214400