The differences and connections between 6061-T6 and 6061-T651 aluminum alloys lie primarily in their temper designations and the specific processing steps that result in their mechanical properties. Here's a detailed explanation:
1. Common Characteristics
Both 6061-T6 and 6061-T651 belong to the 6061 aluminum alloy family and share similar base properties:
Composition: Both contain magnesium and silicon as their primary alloying elements.
Applications: Used widely in structural components, aerospace, transportation, and more due to their high strength, good corrosion resistance, and excellent machinability.
2. Differences
| Property/Aspect | 6061-T6 | 6061-T651 |
Temper Definition | T6 refers to a solution heat-treated alloy that is artificially aged to achieve its maximum strength. | T651 includes the same process as T6 but adds stress-relieving by stretching. |
Stress Relief | Not stress-relieved, meaning there might be residual stresses from heat treatment. | Stress-relieved by stretching (1–3% elongation) after solution heat treatment, reducing residual stresses. |
Dimensional Stability | Can distort under machining due to residual stress. | Improved stability, less prone to warping during machining. |
Common Form | Typically supplied as sheet, plate, or extrusions. | Primarily supplied as thicker plates. |
3. Connection
Base Material: Both are derived from the 6061 aluminum alloy and undergo solution heat treatment and artificial aging to enhance mechanical properties.
Strength: Both have comparable tensile and yield strength levels, as the primary temper processes (T6) are identical.
Versatility: Their uses often overlap, with T651 favored for applications needing high dimensional stability during machining.
When to Choose 6061-T6 vs. 6061-T651
6061-T6: Ideal for general-purpose structural applications where residual stress is not a concern.
6061-T651: Better for machining-intensive applications where dimensional stability is critical.
By understanding the difference in stress relief and stability, you can select the appropriate temper for your project needs.