Welding or brazing 3D printed stainless steel

Has anyone welded or brazed any 3D printed stainless steel objects? Apparently 3D printed stainless uses bronze as a binding agent.

According to the Shapeways website:
This material is 3D printed 420 Stainless Steel infused with bronze, and has a final composition of approximately 60% steel and 40% bronze.

https://www.shapeways.com/materials/steel

I was going to experiment with a custom 3D printed part(fork dropouts). After reading the material specification, I have changed my mind. Too bad, because the technology offers a lot of potential for customization.

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Originally Posted by incepi

Has anyone welded or brazed any 3D printed stainless steel objects? Apparently 3D printed stainless uses bronze as a binding agent.

According to the Shapeways website:
This material is 3D printed 420 Stainless Steel infused with bronze, and has a final composition of approximately 60% steel and 40% bronze.

https://www.shapeways.com/materials/steel

I was going to experiment with a custom 3D printed part(fork dropouts). After reading the material specification, I have changed my mind. Too bad, because the technology offers a lot of potential for customization.

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As far as I understand it Shapeways offers DMLS (direct metal Laser Sintering) which fuses a metalic alloy of some kind. Sometimes with a binder. What you would be looking for is SLM (selective laser melting) which is essentially the same but is higher power and melts pure metals together (ti, stainless etc). Shapeways does not offer this.

It is an awesome technology but at today's current costs it would really only be for prototyping. I.e. get ready to pay 1500 or so to have your fork parts made. If you Boeing its no biggie.

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Originally Posted by dbohemian

As far as I understand it Shapeways offers DMLS (direct metal Laser Sintering) which fuses a metalic alloy of some kind.

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I think the SS / Bronze parts are done by binder jetting and post cure infiltration rather than DMLS. This explains the high bronze percentage.

ive seen a fair bit of shapeways 3d printed 'stainless' in the flesh and the above replies seem on point.

from their web here; Stainless Steel 3D Printing Material Information - Shapeways

'Steel is printed by depositing a liquid binder onto a bed of steel powder one layer at a time. The product is then removed from the printer and infused with bronze. While the product is being transferred from the printer to the infusion chamber, it exists in a delicate "green state" which does not support interlocking parts."

'It is heat resistant to 831ºC / 1528ºF degrees. Higher temperatures may significantly change material properties. '

'To build steel models, special 3D printers deposit small drops of glue onto layers of stainless steel powder, one layer at a time, until the print is complete. We carefully remove these models from the printer. At this stage of the process, the objects are very fragile, similar to wet sand. The models then go through an infusion process that replaces the glue with bronze, creating a full metal product. Models are then processed to achieve your desired finish, sprayed with a sealant, and shipped to you.'

im replying because ive thought about it a fair bit as a way of building weird angle/tube combo lugs, and i think this could work incredibly well in certain places, though being a pretty new application of the process&resulting material, i want to do alot of testing before anyone rides it..

someone who knows more thna me may comment on these figures from there material data sheet;

Stainless Steel

Specifications

Alloy Family:
420

SS+ Bronze
(40% bronze)

UTS:
99 KSI (682 MPa)

Yield:
66 KSI (455 MPa)

Modulus:
21.4 MPSI (147 GPa)

Elongation:
2.30%

Hardness:
20-25 HRc

You can machine it, drill and tap it, weld it, and even RAM or wire EDM it. A machinist evaluated the material as tough enough to need a carbide bits to mill or drill it. There are customers who printed
turbine impellers and run them at 3500 rpms for testing purposes.

(uhh, rpms?)

My area of concern with those properties is that the yield strength is reasonably low, not far above mild steel, but unlike mild steel the strain to failure is also quite low. The low yield strength of mild is at least compensated by the fact that if the part bends you can usually just bend it back again. This stuff will just snap.

I'd be interested to see Charpy results.

I would try shooting Spencer Wright an email about it. He's been experimenting with 3D printing titanium components, and has done a really good job documenting his journey. While it's not exactly what you're looking for he seems like he'd be good resource to check with.

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Originally Posted by Mark Kelly

the yield strength is reasonably low, not far above mild steel, but unlike mild steel the strain to failure is also quite low. The low yield strength of mild is at least compensated by the fact that if the part bends you can usually just bend it back again. This stuff will just snap.

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thankyou sir for your time, you have saved me a fair bit.
( except the time im now going to spend reading about charpy impact tests... ha )

Through my fabrication business I am in the process of getting some parts printed and then s/s cast, they also do s/s printing of which I am getting samples, for exactly his reason, let you know what happens.

I'd be really surprised if someone hasn't done Charpy testing on most of these materials. I have always wondered about fatigue.

Hey guys,

So as Samson mentioned, I've had a bunch of parts printed by DMLS and EBM. With those technologies, a powdered material (titanium, in my case, but also 17-4, inconel, cobalt chrome, tool steel, and others) are fused together by an energy source (laser for DMLS, electron beam for EBM. The parts that come off of these machines are generally as strong as forged parts. They're also expensive; my seatmast topper is between $500 and $1000 apiece, in quantities in the dozens.

Shapeways uses DMLS for their "raw aluminum" material (not listed on the materials page - it's in pilot only), but their "stainless steel" parts are made by ExOne, and are indeed a binder jet -> brass infusion process. I would NOT recommend using them for mechanical components.

Generally speaking, DMLS and EBM are NOT a good replacement for CNC. There are some advantages to 3D printing, but the design guidelines are totally different and the first time pass rate is extremely low. But I'm bullish on the technology, especially for high end cycling. It offers a few key advantages over conventional manufacturing, and we've really only just begun to explore applications outside of aerospace, medical implants, and tool & die. It's always going to be a high end technology, but like other high performance, expensive materials (carbon fiber composites, kevlar, ceramics, etc) I'd be surprised if more and more applications don't show up in the next few years.

Always happy to chat more about this - just drop a line!

S

3D printing is a great technology for prototyping. I do most of my concepts in plastic now to evaluate fit and form, as well as design aesthetics. No tooling costs means you can experiment as much as you want.

It is possible to cast 3D printed plastic parts using lost plastic instead of lost wax. I've made a couple of small parts and had them cast by a local jeweller. I have yet to source out a supplier to cast larger steel or aluminum parts in small quantities.

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Originally Posted by EricKeller

I'd be really surprised if someone hasn't done Charpy testing on most of these materials. I have always wondered about fatigue.

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yep,
and therein lies the key point for any material you want to build a bicycle frame with. Fatigue performance. The term was 'notch sensitivity' in my engineering study. Given that a bicycle frame is a fatigue-failure resisting structure (of a desired stiffness, achieved at the lowest possible weight) 'notch sensitivity' is the key feature of the material. Aluminium frames for example had to be made very stiff and inflexible (and then sold to us by the marketing departments) in order to achieve anything resembling the lifespan of a good alloyed-steel frame because the material itself couldn't be both supple and resist premature fatigue failure. A frame made of glass anyone?

Most of a bicycle frame is structural and has over time been pared back to the minimum so ideally it's all on the verge of failure but without anywhere for a failure to start (with good design that doesn't add dumb stress-risers). Also, much of what I've seen designed on computer lately is apparently ignorant of what and why things failed in the past. Garbage in, garbage out. But the cool factor seems to trump that for some.... for the short term at least.

3D printed prototypes for investment castings are fantastic!