Alloy Characteristics for Machining
6061 is an Al-Mg-Si alloy whose main alloying elements are magnesium and silicon, with a small amount of copper. It offers medium strength, good plasticity, and excellent corrosion resistance, and it has no tendency toward stress corrosion cracking in normal service. These traits make it an outstanding general-purpose machining material: it cuts cleanly, holds tolerances, welds well, and accepts anodizing and painting. Because it contains a little copper, its strength is higher than 6063, but its quenching sensitivity is also higher, so after extrusion it requires solution treatment and artificial aging to reach full strength.
Available Grades and Sizes
Suppliers offer 6061 sheet and plate in thicknesses from 0.3 mm to 500 mm, widths from 100 mm to 2800 mm, and lengths from 500 mm to 16000 mm, with custom dimensions on request. Common tempers include O, T4, T6, T651, and H112. T651 is particularly popular for machining because the stretching step relieves internal stress and keeps plates flat during material removal. Surface options include hairline, mill, anodized, mirror, and embossed finishes, and OEM services such as perforating, cutting to size, flattening, and surface treatment are available.
Mechanical Properties
Typical minimum mechanical properties for 6061 plate are a tensile strength of at least 180 MPa, a yield strength of at least 110 MPa, and an elongation of at least 14% in the appropriate temper. In the T6 condition, values are considerably higher, with tensile strength commonly around 290 MPa. Because properties vary with thickness and temper, the material test report should be checked against the application. For structural use, design against the guaranteed minimums rather than typical values.
Applications in Precision Machining
6061 sheet and plate are used across a wide range of industries: mobile phone card slots and phone casings, injection and stamping molds, automotive components, mask machines, jigs and fixtures, electronic enclosures, and general industrial structural parts. The alloy suits applications that need certain strength, high corrosion resistance, and a good surface for anodizing or painting. Its weldability also makes it convenient for fabrications that combine machined parts with welded assemblies.
Quality Assurance for Machining Stock
Consistent machining results depend on consistent material. Look for suppliers that provide mill test certificates, control thickness tolerance and flatness, and can supply pre-production samples. For critical applications, third-party inspection and confirmation of temper and composition protect against out-of-spec material. Seaworthy export packaging protects the sheet surface and flatness during international shipping, and delivery options include container or bulk vessel shipment from major ports.
FAQ
Which temper is best for CNC machining?
T651 is the most common choice because stress relief keeps large plates flat and stable during machining. T6 is also machinable, but large sections may move more when material is removed.
Can 6061 sheet be anodized after machining?
Yes. 6061 anodizes well and produces a consistent, attractive finish. Clean the machined surface thoroughly and follow the anodizer's deoxidizing steps for uniform results.
What is the maximum thickness available?
6061 plate is commonly available up to 500 mm thick for heavy machining and tooling applications. Standard sheet covers the thinner range from 0.3 mm upward.
Is 6061 suitable for welding in structural assemblies?
Yes. It is one of the most weldable heat-treatable alloys, but the weld zone loses some aged strength. Design accordingly, or specify post-weld heat treatment when maximum strength is required.
Why does 6061 cost more than 6063?
6061 contains additional alloying elements, including a small amount of copper, and requires solution treatment and aging for full strength. This raises material and processing costs compared with 6063.