What is the best aluminum for forging?

Choosing the right aluminum alloy for your forging project can feel overwhelming, can't it? With so many options, you want to ensure you pick one that provides the strength, durability, and workability your application demands. The "best" isn't always a straightforward answer.

The best aluminum for forging depends heavily on the specific application's requirements, but alloys like 6061, 7075, and 2014 are popular choices due to their excellent forgeability, strength characteristics, and ability to be heat-treated for enhanced properties.

At SWA Forging, we've been deep in the world of aluminum forging since 2012. We specialize in manufacturing and exporting customized, large-diameter forged rings and forged discs. Our clients, primarily traders and machining companies in the Middle East, often ask us about the ideal aluminum alloys for their specific needs. Experience has taught us that while certain alloys are frequently requested, the "best" truly hinges on the end-use. Let's explore some key considerations.

Is 6061 aluminum formable?

You might hear a lot about 6061 aluminum, but a key question is its suitability for shaping. Can it actually be formed effectively through the intense forging process? This is vital if you're considering it for complex parts.

Yes, 6061 aluminum is highly formable, especially when heated to typical forging temperatures. Its good ductility and malleability make it one of the most versatile and widely used aluminum alloys for forging applications.

The formability of 6061 aluminum¹ is one of its standout features, making it a favorite for many forging operations, including ours at SWA Forging. This alloy contains magnesium and silicon as its main alloying elements. These elements contribute to its good mechanical properties and its ability to be easily worked.
When we forge 6061, we typically heat the billets to temperatures ranging from 350°C to 500°C (660°F to 930°F). At these temperatures, the material becomes much softer and more ductile, allowing it to flow and fill the forging dies under pressure without cracking. This results in parts with excellent structural integrity and refined grain structure.
After forging, 6061 can be heat-treated to various tempers, with T6 (solution heat-treated and artificially aged) being the most common. The T6 temper significantly increases its strength and hardness, making the final forged part suitable for a wide array of applications, from structural components to machinery parts. Many of our clients who require forged rings and discs for machining choose 6061-T6 for its excellent balance of strength, corrosion resistance, weldability, and, importantly, its good machinability after forging. We've forged countless tons of 6061, and its reliable formability is a key reason for its popularity.

What is the tolerance of aluminum forging?

When you're designing a part, precision is key, isn't it? So, how accurately can aluminum be forged? Understanding the typical tolerances helps manage expectations and plan for any necessary secondary machining operations.

Forging tolerances for aluminum vary based on part size, complexity, alloy, and the forging process (open-die vs. closed-die). Generally, they are tighter than sand casting but looser than machining, often ranging from +/- 0.5mm to several millimeters.

Achieving tight tolerances in aluminum forging is something we strive for at SWA Forging, but it's influenced by several factors.

1. Die Design and Wear: The precision of the forging dies is critical. As dies wear over time with repeated use, tolerances can slightly widen.
2. Part Size and Complexity: Larger and more complex parts generally require wider tolerances compared to smaller, simpler shapes. Maintaining tight tolerances over a large surface area is more challenging.
3. Alloy Type: Different aluminum alloys can have slightly different flow characteristics during forging, which can influence the final dimensions.
4. Forging Process:
   • Open-Die Forging: This process, often used for larger parts like the rings and discs we produce, generally has wider tolerances as the metal is shaped between flat or simple contoured dies.
   • Closed-Die Forging (Impression Die Forging): This uses dies that fully enclose the workpiece, offering tighter tolerances and producing parts closer to their final shape ("near-net shape").
5. Industry Standards: Tolerances are often guided by standards such as those from the Forging Industry Association (FIA) or specific ISO standards. For general guidance, typical "commercial" tolerances for closed-die aluminum forgings might be around ±0.8mm for small dimensions, increasing with part size. For open-die forgings, these can be greater.

Many of our forged rings and discs are supplied as "near-net shapes," meaning they are close to the final dimensions but will undergo further machining by our clients. We always work closely with our customers to understand their specific tolerance requirements and ensure our forging process meets their expectations, providing product quality certificates for every order.

Which is better, 6061 or 7075 aluminum?

It's a common showdown in the aluminum world: 6061 versus 7075. Both are popular, but they have distinct strengths. Which one comes out on top for your needs? The answer really depends on your priorities.

Neither 6061 nor 7075 aluminum² is universally "better"; 7075 offers significantly higher strength, while 6061 provides better weldability, corrosion resistance, formability, and is generally more cost-effective. The choice depends on the specific application's demands.

Choosing between 6061 and 7075 aluminum is a frequent consideration for our clients at SWA Forging. Both are excellent alloys, but they excel in different areas. Here's a breakdown to help decide:

When to choose 6061: If your application requires a good balance of strength, excellent corrosion resistance, good weldability, and formability, and cost is a significant factor, 6061 is often the preferred choice. Many of our general industrial and machining clients opt for forged 6061 rings and discs.
When to choose 7075: If absolute maximum strength-to-weight ratio is the primary concern, and you can design around its lower corrosion resistance and poor weldability (or don't require welding), then 7075 is superior. This is often the case for aerospace or highly stressed mechanical components.
At SWA Forging, we guide our customers based on their specific needs. For traders who need versatile stock, 6061 might be more common. For machining companies creating high-performance parts, 7075 might be specified. We ensure that whatever the choice, the forged product meets the highest quality standards, complete with certifications like ISO 9001 and third-party reports from SGS, BV, or TUV if requested.

What is the hardness of 6061 aluminum?

When selecting materials, hardness is often a key factor, isn't it? It tells you about wear resistance and can relate to strength. So, just how hard is 6061 aluminum, a common choice for many forged parts?

The hardness of 6061 aluminum varies significantly with its temper. In the commonly used T6 temper, 6061 typically has a Brinell hardness of around 95 HB and a Rockwell B hardness of approximately 55 HRB.

Hardness is a measure of a material's resistance to localized plastic deformation, such as indentation or scratching. For 6061 aluminum, this property is primarily determined by its heat treatment condition, known as its temper.

• Annealed (O Temper): In its softest state (6061-O), after annealing, the Brinell hardness can be as low as 30 HB. This temper is used when maximum formability is needed before subsequent strengthening.
• Solution Heat-Treated and Artificially Aged (T6 Temper): This is the most common temper for 6061 and provides a significant increase in both strength and hardness. For 6061-T6, typical hardness values are:
  • Brinell Hardness (HB): Approximately 95 (using a 500kg load and 10mm ball)
  • Rockwell B Hardness (HRB): Approximately 55-60
  • Vickers Hardness (HV): Approximately 107
• Other Tempers (T4, etc.): Other tempers will have intermediate hardness values. For example, 6061-T4 (solution heat-treated and naturally aged) will be softer than T6 but harder than O.

At SWA Forging, when we produce forged rings or discs from 6061 aluminum, they are often supplied in the T6 or T651 temper to provide the optimal combination of strength, hardness, and machinability for our clients. This increased hardness contributes to better wear resistance and indicates that the material has achieved its desired strength properties. We ensure through rigorous quality control, in line with our ISO certifications, that the material meets the specified temper and its associated mechanical properties, including hardness. Our clients rely on this consistency for their subsequent machining and assembly processes.

Conclusion

The "best" aluminum for forging ultimately aligns with your project's specific mechanical, environmental, and cost needs. Alloys like 6061 and 7075 are strong contenders, offering distinct advantages for various demanding applications.