Metal 3D Printing Material Selection: Which Metal Should Your Part Be Printed In?
There is no best metal for 3D printing. There is only the one your part survives — and for most parts, several candidates fall away in the first two questions. Metal 3D printing material selection goes wrong in a predictable way: the comparison starts from the material chart and works backwards to the part, instead of starting from the part and eliminating.
Every alloy we print has a page on this site with its full property set, and those pages are the right place to go once a metal is chosen. What they cannot do is choose it for you, because each one is written to be complete rather than comparative. This article is the comparative layer for metal 3D printing material selection: the questions, the order they go in, and the point at which each answer eliminates alloys.
Temperature first, then environment, then load, then cost. Asked in this order, the four questions eliminate most alloys before price is ever discussed.
Asked in the order buyers usually ask them — strongest first, cheapest second — they do not eliminate anything. They just rank four metals you may not be able to use, and the ranking sends you to the wrong page.
Why does “which metal is best” not have an answer?
Because the question is missing its subject. Best at what? Our four metals are each best at something none of the others do, and each of them is genuinely wrong somewhere:
- Grade 5 titanium — highest strength per gram we run, and effectively immune to seawater and chlorides. It is also the most expensive thing we print, the slowest, and poor against itself in sliding contact.
- AlSi10Mg — the lightest metal we print and a real heat-sink material. It is also the softest, and it loses its printed structure above a modest service temperature.
- 316L stainless — the workhorse: ductile, weldable, machines properly, survives chlorides and process chemistry. It is also nearly twice the density of aluminium and useless as a heat sink.
- Copper and its alloys — the best electrical and thermal conductors available to us, by a wide margin. It is heavy, soft, creeps under sustained load, and the hardest metal on our floor to print.
Each of those lists is published in full on our material pages — titanium, aluminium, 316L and copper — and each is written from that alloy's point of view. A buyer comparing four of them at once needs a different document, and the comparison has to start somewhere other than the datasheets.
What should you decide first, and what can wait?
Start with the two questions that only ever subtract. Service temperature and environment are constraints: if the part fails them, no property of that alloy matters, because the part will not be there. Load and cost are rankings: they decide between survivors, and they are worth discussing only once you have survivors.
Run in this order, metal 3D printing material selection stops being a search across a chart and becomes a subtraction with an end point: usually one or two alloys standing That is the useful outcome, because it converts an open-ended search into a comparison of few options — and it stops you spending engineering time on a material you were never going to specify.
THE ELIMINATION ORDER
Which question eliminates the most alloys?
Service temperature, by a wide margin, because it is the only question with a hard cliff rather than a gradient. Aluminium AlSi10Mg is published at roughly 170 °C continuous as-built, and above that the fine printed silicon structure coarsens and strength falls away quickly. That is not a derating curve you can design around; it is the point where the printed condition stops being the condition.
The other three metals do not have that cliff at the temperatures most buyers ask about. Titanium and 316L are both published at around 400 °C continuous, with 316L tolerating short excursions to 800 °C with scaling but no structural collapse. Pure copper is the outlier in the other direction: around 200 °C in structural terms, though CuCrZr and GRCop hold strength considerably higher.
So one question — how hot does this part get, continuously — removes aluminium from consideration for a meaningful share of industrial work, and it costs you thirty seconds to ask. Asking it first is why the rest of the selection is short.
When does the answer turn out to be copper?
When conductivity is the specification, and the question is worth asking in that form. If the part exists to move heat or current — a cold plate, an induction coil former, a conformal-cooled manifold, a waveguide — then strength is not what you are optimising, and picking the strongest alloy would be picking the wrong one.
Our published figures for copper make the case in one line: roughly 400 W/m·K thermal for pure copper, about 27 times 316L and 57 times titanium. No other metal we print is within an order of magnitude. Against that, pure copper is published at around 210–250 MPa tensile, it creeps under sustained load, and it tarnishes without a coating.
Within copper there is a second decision, and it is a real one. The three grades we run trade conductivity against strength at temperature: C11000 at about 100 % IACS, CuCrZr at 75–85 % IACS and roughly 350–450 MPa, GRCop-42 at 85–90 % IACS and roughly 400–500 MPa. If maximum conductivity is the whole point and the geometry is not extreme, that is C11000. If the part also has to survive heat, that is CuCrZr or GRCop-42. We will look at a pure-copper part in detail separately.
One practical note that belongs in this section rather than a FAQ: copper reflects roughly 95 % of the infrared light a standard 1064 nm fibre laser produces, which drains heat out of the melt pool as fast as the beam delivers it. It is the hardest metal we print, so we quote copper jobs only after an engineer has looked at the geometry.
When is strength per gram the deciding number?
When the part is carrying load and its mass is the problem — anything that flies, walks, accelerates or has to be moved by a person repeatedly. That is titanium territory, and the published comparison is not close: 900–1100 MPa tensile at 4.43 g/cm³, which our titanium page states as roughly 57 % of the weight of steel at comparable strength.
The trap here is that strength per gram is a ratio, and ratios hide their denominator. Titanium wins it partly because steel loses it: 316L is published at 7.9 g/cm³ and 480–620 MPa, and 316L is 78 % heavier than titanium at a strength roughly half to two-thirds as high. If mass is not actually your constraint, that comparison is not yours to have.
The second trap is that stiffness and strength are different properties, and printed metal has a wide gap between them. Young’s modulus is a property of the alloy and barely moves with printing: about 110 GPa for titanium, about 200 GPa for 316L, about 70 GPa for AlSi10Mg. A part can be entirely strong enough and still deflect too far — and on a thin bracket or a long arm, stiffness is usually what fails first, not strength. Our wall-thickness article covers the structural side of that; the material point is that the fix is often a change of alloy rather than a thicker wall.
When is 316L the right answer even though it is the heaviest?
More often than people expect, because 316L is the forgiving option. It is published at 20–35 % elongation at break, which means a printed steel joint yields and deforms before it fails rather than snapping — and that is worth a great deal on a first article, a load case nobody has modelled properly, or a part that will be iterated.
Three further things make it the default in a lot of industrial work. It machines and threads properly, where titanium machines gummy and work-hardens. It welds to itself and to dissimilar steels by ordinary methods, without post-weld cracking. And it holds at least 99.5 % relative density across a wide, forgiving process window.
Its weakness is thermal, not mechanical. At around 15 W/m·K it is a poor heat sink, and its coefficient of thermal expansion is higher than titanium’s — about 16 against 8.6, both in 10⁻⁶ per kelvin — which matters on long parts and mixed-metal assemblies. Being slightly ferromagnetic as printed also matters in front of magnetic sensors, though usually only when someone asks about it.
Where does the cost question actually belong?
Last, and only between survivors. Cost has two components that buyers routinely merge: the material itself and everything that follows from the choice — machining, finishing, support removal, sectioning a part that will not fit the build envelope, and lead time. A cheaper alloy that needs more finishing is not cheaper, and a titanium part that fits in one build may be both faster and cheaper than an aluminium one delivered in sections.
We publish material property data rather than a price list on the site, and any quote we send goes through the quote form where the geometry is reviewed — because on a printed part the geometry, not the alloy name, is usually what moves the number. If you want to see how that number is built before you commit to a material, our article on what a 3D printing quote actually contains sets out the lines and which of them dominates.
How do you ask a supplier to check your choice?
Four questions, and what you are really testing in each is whether they are reading your drawing or repeating their own datasheet.
| What to ask | Why it matters | A weak answer sounds like |
|---|---|---|
| What is the service temperature, continuously? | It is the only question with a hard cliff, and it is the one most often skipped. | “It depends on the application.” |
| What does this alloy give up at that temperature? | Every alloy has a line where a property changes character, not just a number. | Repeating the room-temperature figure. |
| Is the load static, cyclic, or impact? | Ductility is worth more than strength on cyclic and impact cases, and nobody is told which they have. | Quoting tensile strength only. |
| What does the geometry do to this choice? | Sectioning, supports and post-machining change the cost shape, sometimes more than the alloy does. | Quoting per-kilo figures instead of per-part. |
All four are answerable from a drawing and a paragraph about the application. If a supplier cannot answer them, the quote you get back is a price for a material rather than a price for your part, and the two come apart somewhere downstream.
Where this leaves you
Metal 3D printing material selection is a subtraction problem wearing a comparison’s clothes. Ask how hot the part gets, ask what it touches, ask what carries the load and how much of it there is, and only then ask what it costs — and most of the field is already gone. What survives is usually one metal, occasionally two, and the decision after that is a real engineering one rather than a ranking exercise.
If you send a drawing with the service temperature and the environment written on it, tell us those two things first. It is the fastest possible conversation about which metal, and it usually ends with a cheaper alloy than the one you came in asking about.