Products Description
1. Material Overview & Manufacturing Process
The 6061 large diameter aluminum alloy forging ring is a highly versatile heat-treatable aluminum-magnesium-silicon alloy (Al-Mg-Si series), widely popular for its excellent all-round performance. It offers a good balance of strength and toughness, coupled with outstanding corrosion resistance, excellent weldability, and good machinability. Large diameter thick-walled forged rings leverage the advantages of the forging process, resulting in a dense internal structure, refined grains, and an optimized grain flow aligned along the ring’s circumference, ensuring excellent reliability and long service life in various industrial applications. Although 6061’s strength is not comparable to 7xxx or 2xxx series alloys, its balanced properties make it an ideal choice for large structural components where cost, machinability, and corrosion resistance are all important considerations.
Primary Alloying Elements:
Magnesium (Mg): 0.8-1.2% (strengthens with silicon, improves strength and corrosion resistance)
Silicon (Si): 0.4-0.8% (strengthens with magnesium, enhances age-hardening response)
Copper (Cu): 0.15-0.40% (increases strength)
Chromium (Cr): 0.04-0.35% (inhibits recrystallization, improves toughness)
Base Material:
Aluminum (Al): Balance
Controlled Impurities:
Iron (Fe): 0.7% max
Manganese (Mn): 0.15% max
Zinc (Zn): 0.25% max
Titanium (Ti): 0.15% max
Other elements: 0.05% max each, 0.15% max total
Premium Forging Process (for Large Diameter Thick-Walled Rings): Producing 6061 large diameter thick-walled aluminum alloy forged rings requires precise control over melting, forging, and heat treatment processes to ensure the material achieves the desired comprehensive properties, especially uniformity in thick sections:
Melt and Ingot Preparation:
Standard-compliant primary aluminum and alloying elements are selected.
Advanced melting, refining, and degassing technologies are employed to ensure good melt cleanliness, minimizing non-metallic inclusions and gas content.
Large Direct-Chill (DC) casting systems are used to produce large diameter ingots with uniform microstructure and no significant segregation.
Ingot Homogenization Treatment:
The ingots undergo precisely controlled homogenization annealing (typically at 550-580°C for several hours) to eliminate macrosegregation, dissolve coarse secondary phases, and improve the ingot’s ductility, preparing it for subsequent high-deformation forging.
Billet Preparation and Inspection:
Ingot surface conditioning (scalping or milling) to remove all surface defects.
100% ultrasonic inspection is performed to ensure the ingot is free of any internal defects (e.g., cracks, porosity, large inclusions) that could affect final performance, typically meeting industry standards.
Preheating: The billet is uniformly heated to the precise forging temperature range (typically 400-500°C) to ensure optimal ductility while avoiding incipient melting.
Forging Sequence (Large Diameter Thick-Walled Ring Forgings):
Application of Large Equipment: Large hydraulic presses and ring rolling machines are required to apply sufficient deformation force to heavy billets, ensuring that the core of thick-walled rings also undergoes full plastic deformation and grain refinement.
Upsetting and Pre-forging: On large hydraulic presses, large ingots undergo multi-directional, multiple upsetting and drawing operations to break down as-cast grains, eliminate internal porosity, and form suitable preform shapes.
Piercing: On the press, a preliminary ring structure is formed by piercing with dies or mandrels. This process further compacts the material and refines the microstructure.
Ring Rolling Formation: This critical ring rolling process is performed on large vertical ring rolling machines. Continuous radial and axial compression is applied to the ring preform by a main roll and a mandrel roll, continuously increasing the ring’s diameter while reducing its wall thickness and height. Ring rolling achieves significant plastic deformation, highly aligning the grain flow along the ring’s circumference, ensuring excellent circumferential strength, toughness, and fatigue performance. For thick-walled parts, uniform grain flow throughout the entire wall thickness must be ensured.
Minimum Reduction Ratio: Typically requires at least 3:1 or higher to ensure complete elimination of the as-cast structure and formation of optimized grain flow and dense microstructure.
Heat Treatment:
Solution Heat Treatment: The forging is heated to a precise solutionizing temperature of approximately 530-545°C and held for sufficient time to fully dissolve alloying elements (Mg, Si, Cu) into the aluminum matrix, forming a uniform solid solution.
Quenching: Rapid cooling from the solutionizing temperature (typically water quenching, ensuring water temperature and cooling rate meet thick-walled part requirements) to retain the supersaturated solid solution. For thick-walled parts, quench uniformity is critical for final properties.
Aging Treatment (T6 Temper): Standard artificial aging treatment (typically at 160-180°C for 8-18 hours). This treatment causes the precipitation of strengthening phases like Mg₂Si and some Al₂Cu, achieving maximum strength and hardness.
Residual Stress Relief (T651/T652 Tempers): For large diameter thick-walled rings, stretching (T651) or compression (T652) stress relief is often performed after quenching to significantly reduce residual stress, minimize machining distortion, and improve dimensional stability.
Finishing & Inspection:
Deburring, straightening, dimensional inspection, surface quality checks.
Finally, comprehensive nondestructive testing (e.g., ultrasonic, penetrant) and microstructural analysis are performed to ensure the product complies with industry standards and customer requirements.
2. Mechanical Properties of 6061 Large Diameter Thick-Walled Forged Ring
The mechanical properties of 6061 large diameter thick-walled aluminum alloy forged rings depend on the specific thickness, heat treatment temper, and optimization of the forging process. T6 and T651/T652 are the most commonly used tempers for 6061.
| Property | T6 (Typical) | T651/T652 (Typical) | Test Method |
| Ultimate Tensile Strength (UTS) | 290-330 MPa | 290-330 MPa | ASTM E8 |
| Yield Strength (0.2% YS) | 240-290 MPa | 240-290 MPa | ASTM E8 |
| Elongation (2 inch) | 10-18% | 10-18% | ASTM E8 |
| Hardness (Brinell) | 95-105 HB | 95-105 HB | ASTM E10 |
| Fatigue Strength (5×10⁷ Cycles) | 95-115 MPa | 95-115 MPa | ASTM E466 |
| Fracture Toughness (K1C) | 25-35 MPa√m | 25-35 MPa√m | ASTM E399 |
| Shear Strength | 190-220 MPa | 190-220 MPa | ASTM B769 |
Property Distribution and Anisotropy:
6061 forged rings, through the ring rolling process, have grain flow highly aligned along the ring’s circumference. Therefore, circumferential (tangential) properties are typically optimal. Radial and axial properties are relatively lower but still sufficient for most structural component needs.
Thickness Effect: For 6061, large diameter thick-walled forgings also maintain good uniformity of properties from core to surface, thanks to its excellent hardenability.
Residual Stress: T651/T652 tempers, through stretching or compression stress relief, significantly reduce quenching residual stress, minimize machining distortion, and improve dimensional stability.
3. Microstructural Characteristics
The microstructure of 6061 large diameter thick-walled aluminum alloy forged rings is the basis for their good overall performance.
Key Microstructural Features:
Grain Structure and Grain Flow:
The forging process breaks down coarse as-cast grains, forming fine, uniform recrystallized grains and elongated non-recrystallized grains aligned along the forging direction.
Grain Flow: During ring rolling, grains are intensely elongated and form a continuous fibrous structure along the ring’s circumference. This grain flow highly matches the main stress direction of the ring, significantly improving circumferential strength, fatigue life, and toughness. For thick-walled rings, grain flow is uniformly distributed throughout the entire section.
Dispersoids: Fine dispersoids formed by Chromium (Cr) effectively inhibit recrystallization and grain growth, ensuring a fine-grained microstructure.
High Density and Defect Elimination:
The immense pressure applied during the forging process completely closes internal defects, such as porosity, shrinkage cavities, and gas pockets, that may arise during casting, significantly improving the material’s density and reliability.
Effectively breaks down and uniformly disperses small amounts of primary intermetallic compounds and impurities (e.g., Fe, Si phases), reducing their detrimental effects.
Strengthening Phase (Precipitate) Distribution:
T6 aging treatment causes the precipitation of the primary strengthening phase Mg₂Si, along with some Al₂Cu precipitates. These precipitates are uniformly distributed within the grains, providing strengthening.
Precipitates at grain boundaries are usually fine and do not easily lead to severe intergranular corrosion.
Metallurgical Cleanliness:
Standard melting and casting technologies ensure low non-metallic inclusion content, meeting cleanliness requirements for general engineering applications.
4. Dimensional Specifications & Tolerances
The size range of 6061 large diameter thick-walled aluminum alloy forged rings is wide and can be custom-produced according to engineering requirements.
| Parameter | Typical Manufacturing Range | Commercial Tolerance (As-Forged) | Precision Tolerance (Machined) | Test Method |
| Outer Diameter | 800 mm – 7000+ mm | ±0.8% or ±8 mm (whichever is greater) | ±0.2 mm to ±1.0 mm | CMM/Laser Scan |
| Inner Diameter | 700 mm – 6900+ mm | ±0.8% or ±8 mm (whichever is greater) | ±0.2 mm to ±1.0 mm | CMM/Laser Scan |
| Wall Thickness | 80 mm – 1000+ mm | ±4% or ±8 mm (whichever is greater) | ±0.2 mm to ±1.0 mm | CMM/Laser Scan |
| Height | 80 mm – 1200+ mm | ±4% or ±8 mm (whichever is greater) | ±0.2 mm to ±1.0 mm | CMM/Laser Scan |
| Flatness | N/A | 0.6 mm/meter diameter | 0.15 mm/meter diameter | Flatness Gauge/CMM |
| Concentricity | N/A | 0.6 mm | 0.15 mm | Concentricity Gauge/CMM |
| Surface Roughness | N/A | Ra 6.3 – 25 μm | Ra 1.6 – 6.3 μm | Profilometer |
Customization Capability:
Custom-made forged rings with various sizes, shapes, and tolerance requirements can be produced according to detailed customer drawings and technical specifications.
Typically offered in Rough Machined or Semi-Finish Machined conditions to facilitate subsequent customer machining.
5. Temper Designations & Heat Treatment Options
6061 alloy primarily achieves its mechanical properties through heat treatment.
| Temper Code | Process Description | Optimal Applications | Key Characteristics |
| O | Fully annealed, softened | Intermediate state before further processing | Maximum ductility, lowest strength, easy for cold working |
| T4 | Solution heat treated, then naturally aged | Applications not requiring maximum strength, good ductility | Moderate strength, good ductility |
| T6 | Solution heat treated, then artificially aged | General high-strength structural components | Maximum strength, high hardness, good corrosion resistance |
| T651 | Solution heat treated, artificially aged, stretched stress-relieved | Requires precise machining, high dimensional stability | High strength, minimal residual stress, reduced machining distortion |
| T652 | Solution heat treated, artificially aged, compression stress-relieved | Requires precise machining, high dimensional stability | High strength, minimal residual stress, reduced machining distortion |
Temper Selection Guidance:
T6 Temper: The most commonly used temper for 6061 large diameter thick-walled forged rings, offering the best combination of strength and hardness.
T651/T652 Tempers: For applications requiring precise machining or strict dimensional stability, T651 or T652 tempers are recommended to effectively eliminate quenching residual stress.
6. Machining & Fabrication Characteristics
6061 large diameter thick-walled aluminum alloy forged rings generally have good machinability, but their large size and thick-walled nature still require consideration.
| Operation | Tool Material | Recommended Parameters | Comments |
| Turning | Carbide, HSS | Vc=150-400 m/min, f=0.2-0.8 mm/rev | Large lathes, attention to chip management, avoid entanglement |
| Drilling | Carbide, HSS | Vc=40-100 m/min, f=0.1-0.3 mm/rev | Sharp cutting edges, large helix angle, through-coolant preferred |
| Milling | Carbide, HSS | Vc=150-500 m/min, fz=0.08-0.4 mm | High-rigidity machine tools, attention to chip evacuation |
| Tapping | HSS-E-PM | Vc=10-25 m/min | Proper lubrication, prevents thread tearing |
| Welding | MIG/TIG | Good weldability, select appropriate filler wire (e.g., 4043, 5356) | Strength may decrease after welding, properties in HAZ change |
Fabrication Guidance:
Machinability: 6061 has good machinability, allowing the use of standard aluminum alloy machining tools and parameters. Pay attention to chip management to avoid entanglement.
Weldability: 6061 is one of the few higher-strength aluminum alloys that can be conventionally fusion welded. While strength may decrease after welding, it can be optimized by selecting appropriate filler wire and welding processes.
Residual Stress: Quenched 6061 forgings have residual stress; T651/T652 treatments effectively reduce this. During machining, strategies like symmetric machining and multi-pass shallow cuts should be employed to minimize distortion.
Surface Treatment:
Anodizing: Type II (sulfuric) or Type III (hard) anodizing provides wear resistance, corrosion resistance, and aesthetic appeal.
Conversion Coatings: Chromate or chromium-free conversion coatings serve as primers for paint.
Coatings: Applied for specific protection requirements.
7. Corrosion Resistance & Protection Systems
6061 alloy is renowned for its excellent corrosion resistance, particularly in atmospheric and marine environments.
| Corrosion Type | T6 (Typical) | Protection System |
| Atmospheric Corrosion | Excellent | No special protection needed, or anodizing |
| Seawater Corrosion | Good | Anodizing, coating, galvanic isolation |
| Stress Corrosion Cracking (SCC) | Very Low Sensitivity | T6 temper inherently provides excellent resistance |
| Exfoliation Corrosion | Very Low Sensitivity | T6 temper inherently provides excellent resistance |
| Intergranular Corrosion | Very Low Sensitivity | Heat treatment control |
Corrosion Protection Strategies:
Alloy and Temper Selection: 6061-T6 temper itself provides excellent corrosion resistance, especially against SCC and exfoliation corrosion.
Surface Treatment:
Anodizing: The most common protection method, forming a dense oxide film that enhances corrosion and wear resistance.
Chemical Conversion Coatings: Serve as good primers for paints or adhesives.
Coating Systems: High-performance coatings can be applied in particularly harsh environments.
Galvanic Corrosion Management: When in contact with incompatible metals, isolation measures such as coatings or gaskets must be employed.
8. Physical Properties For Engineering Design
The physical properties of 6061 large diameter thick-walled aluminum forged rings are crucial for the design of large structures.
| Property | Value | Design Consideration |
| Density | 2.70 g/cm³ | Lightweight design, center of gravity control |
| Melting Range | 582-652°C | Heat treatment and welding window |
| Thermal Conductivity | 167 W/m·K | Thermal management, heat dissipation design |
| Electrical Conductivity | 43% IACS | Good electrical conductivity |
| Specific Heat | 896 J/kg·K | Thermal mass and heat capacity calculations |
| Thermal Expansion (CTE) | 23.4 ×10⁻⁶/K | Dimensional changes due to temperature variations |
| Young’s Modulus | 68.9 GPa | Deflection and stiffness calculations |
| Poisson’s Ratio | 0.33 | Structural analysis parameter |
| Damping Capacity | Moderate-Low | Vibration and noise control |
Design Considerations:
Strength-to-Weight Ratio: 6061 offers a good strength-to-weight ratio, suitable for structures requiring lightweighting but not to an extreme degree.
Ease of Fabrication: Good machinability and weldability reduce manufacturing complexity and cost.
Corrosion Resistance: Excellent corrosion resistance makes it suitable for various outdoor and corrosive environments.
Cost-Effectiveness: 6061 is more cost-effective compared to higher-strength alloys.
Operating Temperature: Like all aluminum alloys, 6061 is not high-temperature resistant; recommended operating temperature is below 150°C.
9. Quality Assurance & Testing
Quality control for 6061 large diameter thick-walled aluminum forged rings is a crucial aspect ensuring their performance and reliability.
Standard Testing Procedures:
Raw Material Certification: Chemical composition analysis to ensure compliance with AMS, ASTM, etc., and traceability.
Melting and Forging Process Control: Monitoring temperature, deformation amount to ensure uniform and dense internal structure.
Heat Treatment Process Monitoring: Furnace temperature uniformity, solution quenching, aging curve, etc.
Chemical Composition Analysis: Verification of alloying elements and impurity content.
Mechanical Property Testing:
Tensile Testing: Samples taken in radial, tangential/circumferential, and axial directions to test UTS, YS, EL.
Hardness Testing: Multi-point measurements to assess uniformity.
Impact Testing: If required.
Nondestructive Testing (NDT):
Ultrasonic Testing: Volumetric inspection of the entire ring to detect internal defects.
Penetrant Testing: Detects surface-breaking defects.
Eddy Current Testing: Detects surface and near-surface defects.
Microstructural Analysis: Metallographic examination to evaluate grain size, grain flow, degree of recrystallization, precipitate distribution, defect types, etc.
Dimensional and Surface Quality Inspection: Precise measurements using CMM, profilometer, etc.
Standards and Certifications:
Complies with ASTM B247 (Aluminum Alloy Forgings), AMS 4117 (6061-T6 Forgings), ISO, EN, GB/T, and other industry standards.
Quality Management System Certifications: ISO 9001.
EN 10204 Type 3.1 Material Test Reports can be provided.
10. Applications & Design Considerations
6061 large diameter thick-walled aluminum forged rings are widely used in various industrial sectors due to their excellent overall performance and cost-effectiveness.
Primary Application Areas:
Aerospace Auxiliary Structures: Non-critical aircraft structural components, engine peripheral equipment rings, aerospace ground support equipment.
Marine and Offshore Engineering: Large ship deck equipment, non-load-bearing structures for offshore platforms, marine valve bodies, pipe flanges, etc., benefiting from their seawater corrosion resistance.
General Machinery and Equipment: Large pump bodies, compressor casings, motor mounts, flanges, connectors, load-bearing frames, etc.
Rail Transit: Train body connecting components, non-critical bogie parts, rail equipment.
Automotive Industry: Large components, truck wheels, chassis parts, etc., for weight reduction.
Construction and Structural Engineering: Large truss connectors, decorative structures, bridge components.
Design Advantages:
Good Strength-to-Weight Ratio: Provides sufficient strength for most structural applications while achieving lightweighting.
Excellent Corrosion Resistance: Performs well in atmospheric and marine environments, particularly insensitive to SCC.
Superior Weldability and Machinability: Significantly reduces manufacturing complexity and cost, facilitating subsequent processing and assembly.
High Toughness: Good toughness at room temperature, not prone to brittle fracture.
Cost-Effectiveness: Lower raw material and processing costs compared to higher-performance alloys.
Dimensional Stability: T651/T652 tempers effectively control machining distortion.
Design Limitations:
Strength Limitations: Its strength is not comparable to ultra-high-strength alloys like 2xxx or 7xxx series, making it unsuitable for critical load-bearing structures requiring ultimate strength.
High-Temperature Performance: A common limitation for aluminum alloys; long-term operating temperatures are limited to below 150°C.
Fatigue Strength: Lower fatigue strength compared to 7xxx series, not suitable for extreme cyclic loading environments.
Economic and Sustainability Considerations:
Total Life Cycle Cost: Lower initial cost and good maintenance performance make it highly cost-effective in many applications.
Material Utilization: The forging process helps improve material utilization.
Environmental Friendliness: Aluminum is a highly recyclable material, aligning with sustainable development principles; lightweighting also contributes to reducing energy consumption.
