3104 aluminum alloy is used for many two-piece beverage can bodies because it balances strength, deep drawability, ironing behavior, and light weight; but hardness and elongation specifications only make sense when the temper, gauge, rolling direction, test method, and production stage are stated. A buyer should not compare one supplier's "3104 hardness" or "3104 elongation" number unless the condition and test basis are the same.
The Aluminum Association's Teal Sheet lists 3104 as an aluminum alloy designation, and technical research on AA3104-H19 draw-and-iron can stock shows why the alloy is studied specifically for beverage can forming. The main buyer lesson is that 3104 performance is not a single static property. It changes through rolling, cup drawing, ironing, doming, trimming, coating, and filled-can use.
3104 is selected not because it maximizes one property, but because it gives the can body enough strength after severe forming without losing the process window needed for draw-and-iron production.
Two-piece beverage cans are usually made by drawing a cup from coil stock and then ironing the sidewall to create a thin, tall body. The material must survive deformation without tearing, earing beyond control, excessive thinning, or unstable texture. After forming, it must also support internal pressure, axial load, dome stability, coating, printing, and distribution.
3104 belongs to the 3xxx aluminum-manganese family with magnesium additions. Manganese and magnesium help build strength while keeping the alloy formable enough for can-body manufacturing. This is why 3104 is commonly discussed as can body stock rather than as a lid alloy. Ends and tabs often require different mechanical behavior, so they may use other alloys and tempers.
For beverage buyers, the alloy name matters because it tells you the material family, but it does not prove the finished can's performance. A 3104 can body still needs correct gauge, temper, forming control, coating, seam compatibility, and finished-can testing.
Hardness is a resistance-to-indentation measurement. It gives a quick indication of material strength and work-hardening condition, but it does not directly tell you whether a can will draw, iron, dome, or survive distribution. The hardness method also matters. Brinell, Vickers, Rockwell, or microhardness values are not interchangeable without context.
Typical published material databases often show 3104-H19 can-stock hardness in a relatively high work-hardened range compared with annealed 3104. For buyer use, the safer practice is to request the supplier's COA and method rather than quote a universal number. A typical purchasing packet should state alloy 3104, temper, thickness, tensile strength, yield strength, elongation, hardness method, and acceptance range.
Hardness becomes practical when it is linked to failure modes. If material is too soft, the can body may be more vulnerable to denting, column instability, or dome and sidewall issues after forming. If it is too hard or poorly balanced, the cupper and bodymaker may see tearing, split flanges, ironing instability, or excessive tool wear. The target is a process window, not a trophy number.
In H19 can stock, elongation may look low compared with annealed sheet, but draw-and-iron formability also depends on texture, anisotropy, gauge control, lubrication, and tooling.
Elongation is the strain a tensile specimen can take before fracture. It is useful because it signals ductility, but it is not the only formability measure for D&I can bodies. Can stock is engineered through rolling and temper control so it can draw and iron under very specific tooling conditions. A low-looking elongation value in a hard temper does not automatically mean the material cannot form; it means the value must be interpreted in the correct can-stock context.
The AA3104-H19 research on flow stress and forming behavior highlights that can-stock performance is linked to constitutive behavior, directionality, and forming simulation. That is far more useful than comparing elongation percentages from unrelated tempers. A supplier offering 3104-O, 3104-H19, and finished can bodies may show very different elongation numbers because the material condition is different.
For buyers, the key is to ask whether elongation is reported in the rolling direction or transverse direction, what gauge length was used, what thickness was tested, and whether the value is for incoming coil, cup stock, or finished can-body stock. Without these details, an elongation number can mislead more than it helps.
| Spec field | Why it matters | Buyer caution |
|---|---|---|
| Alloy designation | Confirms 3104 material family and composition control. | Do not treat alloy name as finished-can proof. |
| Temper | Defines work-hardening condition and mechanical behavior. | Compare only the same temper and production stage. |
| Hardness method | Shows whether values are Brinell, Vickers, Rockwell, or microhardness. | Do not mix methods without conversion basis. |
| Elongation | Indicates ductility under tensile test conditions. | Ask for direction, gauge length, and sample condition. |
| Tensile and yield strength | Supports forming and finished-can strength evaluation. | Use with hardness and elongation, not alone. |
| Thickness and tolerance | Controls forming, weight, pressure, and axial performance. | Small gauge changes can affect multiple can properties. |
The table shows why a good COA is more useful than a one-line material claim. The buyer needs a mechanical-property package that can be traced to a lot and interpreted by the can maker or filler.
Because published values vary by source and condition, treat this as an interpretation model rather than a universal specification. Annealed 3104 sheet may show high elongation and low hardness. H19 can-body stock may show much higher hardness and much lower elongation. Finished can bodies may have local property variation because drawing and ironing change the wall, dome, and neck regions differently.
An illustrative buyer rule is to classify the material evidence into three zones. Zone one is "too soft for the intended can body," where denting, axial load, or dome stability could become a concern. Zone two is "balanced can-stock window," where hardness, tensile strength, elongation, and gauge fit the forming process and finished can requirement. Zone three is "too hard or too low ductility for stable forming," where split cups, earing, flange cracks, or ironing defects become more likely. The supplier should define the numeric limits for its process; the buyer should make sure the limits exist and are lot-traceable.
This model prevents a common mistake: chasing maximum strength. A can body is not a structural beam. It is a formed pressure package that must be manufactured at speed. The best material is the one that holds the finished package while staying formable enough for stable production.
A certificate of analysis is useful only when the buyer knows which production stage it describes. A coil COA may describe incoming can-body stock. A finished-can inspection report may describe the formed can. A bodymaker process record may describe how the material behaved during drawing and ironing. These documents are connected, but they are not interchangeable.
For example, elongation in incoming 3104-H19 stock does not tell the buyer the finished sidewall elongation after ironing. Hardness measured on flat stock does not tell the buyer the local hardness at the dome or neck after forming. Tensile strength in the rolling direction does not fully describe transverse behavior or earing tendency. A buyer who treats the COA as a finished-can performance certificate may miss the effect of forming, tooling, lubrication, and process control.
The better reading method is to use the COA as the first gate. It confirms that the right material family and mechanical window entered the can-making process. The second gate is process evidence: cup quality, earing control, ironing stability, trimming, flange quality, and dome forming. The third gate is finished-can evidence: dimensions, axial load, pressure or dome reversal, coating, and seam compatibility. Only all three gates together prove the material became a usable can.
Buyers often compare supplier COA values with online material tables and worry when the numbers do not match exactly. Some differences are legitimate. Online tables may report typical values, minimum values, different tempers, different gauges, different test standards, or values from sheet rather than can stock. The supplier COA should be judged against the agreed specification, not against a random table without matching context.
That said, a large mismatch deserves a question. If the COA lists a temper that does not match the purchase order, if elongation is reported without direction, if hardness has no method, or if tensile values are far outside the agreed range, the buyer should ask for clarification before production approval. The goal is not to catch the supplier in a mistake; it is to prevent material ambiguity from reaching the bodymaker or filling line.
A good RFQ can prevent this problem. Instead of asking for "3104 aluminum cans," ask for can format, alloy family, temper or equivalent can-stock condition, finished can performance evidence, and the specific COA fields you need for your quality file. The more precisely the buyer frames the evidence, the less likely the team is to argue over mismatched numbers later.
Hardness and elongation do not stay in the material lab. They affect cup drawing, wall ironing, earing, flange quality, dome forming, print handling, coating stress, axial load, and pressure performance. A change in coil temper or thickness can show up later as a bodymaker issue, seam problem, dome reversal concern, or warehouse denting complaint.
For carbonated drinks, the finished can must combine body strength, dome stability, seam compatibility, and coating integrity. For export orders, axial load and dent resistance also matter. For slim formats, wall stability and handling sensitivity may be more visible. This is why the material COA should be linked to finished-can inspection and not stored as a disconnected procurement document.
Baixi Cans' aluminum can format options and product pages are where buyers see the finished package. The mechanical-property evidence sits upstream from those pages, but it explains why one can format cannot borrow another format's assumptions without checking material, gauge, and forming data.
If your project has high carbonation, long export routes, slim can formats, hot-climate distribution, or strict filling-line requirements, ask Baixi Cans for a material and finished-can evidence packet. It should include alloy family, temper, can size, thickness or weight target when available, COA fields, finished-can dimensional inspection, pressure or dome evidence when relevant, axial-load evidence when relevant, and lid compatibility.
For a standard format such as a 500ml aluminum beverage can, the material question should be tied to product pressure and route. For a slim or specialty format, the material question should be tied to forming stability and filling-line handling. Use Baixi's contact page to request material and can-performance evidence before finalizing a high-risk order.
3104 is mainly associated with beverage can body stock, while lids and tabs often use different alloys and tempers. Buyers should not assume the body alloy also describes the end, tab, or closure system.
There is no single universal hardness number because method, temper, gauge, and production stage matter. Buyers should request the supplier's COA with the test method, target range, and lot identity instead of comparing isolated values.
H19 can stock is heavily work-hardened, so elongation is lower than annealed sheet. That does not automatically make it unformable because D&I can production also depends on texture, gauge, lubrication, anisotropy, and tooling.
Not always. Higher hardness can improve dent resistance within limits, but excessive hardness or low ductility can increase cracking, tearing, or forming instability. The useful target is a balanced process window.
A useful COA should include alloy designation, temper, thickness, tensile strength, yield strength, elongation, hardness method, lot number, and applicable standard or customer specification. It should connect to the finished can lot.
