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Help choosing materials: copper, bronze, stainless
eligius1427 -
Sunday, April 20, 2008 - 4:03pm
bronze | copper | stainless steel | weathering materials Hi All, I am submitting another proposal for an outdoor public park commission and could use help in choosing a material. There will be two materials involved with the project. The "base" will be out of rusting steel, with an organic element out of another material above it. I want the material to be maintenance free and there will be some forge work and welding involved. The materials I've been considering are Stainless Steel, Bronze, or Copper to create a contrast to the rust color. With the stainless I'd probably try to color it with heat or leave silver, copper patina green, and the bronze I'd either patina brown or green. I have experience fabricating stainless, but not forging any of the materials or welding copper or bronze. My three main criteria are the cost of material, skill level needed, and time involved with forging/fabricating with the material. Copper may not be an option due to theft, but I'd still like peoples opinions. I'd like to hear peoples experiences and opinions of these materials. thanks Jake  Thanks for the comments
eligius1427 -
Monday, April 21, 2008 - 6:07pm
Thanks for the comments Adrian, they're very helpful. Limited experience or not it's more experience than I have with these materials. I am in the process of finishing a project in Brass, and don't think I want to go that route. It's just to fussy. Not sure if Bronze and Copper are just as tricky or not, but that would weigh in a lot on which material I choose. Jake » reply  Complicate...
Fred Zweig -
Tuesday, April 22, 2008 - 2:39pm
The theft issue is not neccessarily something you need to worry about or else all the bronze statues and copper roofs would need to be locked down. I do know that copper theft is rampant in some communities. Alot will depend on what sort of work you plan for this projct. Some metals lend themselves to certain designs and techniques. Red brass is nice to work with and takes on a patina well. I love working with copper due to it's maliability and color. What is the scale of this proposed piece? Fred Zweig » reply Hi Fred, the overall piece
eligius1427 -
Tuesday, April 22, 2008 - 7:16pm
Hi Fred, the overall piece is pretty large. I'm playing with two concepts, the first is an obelisk out of rusting steel roughly 12' tall with large openings in the top 8'. Inside the opening will "float" an organic form of vines, leaves, and flowers, roughly 6' tall and 2' in diameter. The form would require forging and welding of the leaves and flowers, but pretty basic stuff. This is the part that I would like to contrast with the rusting steel. The second concept is a slightly larger version of the organic form, shaped like a sculpted topiary bush. Total size would be around 8' high by 4' in diameter. The elements would be almost the same as above, but there would be some larger stronger vine elements involved for structural purposes Jake » reply Jake, The first concept
Fred Zweig -
Tuesday, April 22, 2008 - 9:50pm
Jake, The first concept sound pretty interesting. Cor-ten steel obelisk with a single high opening. The organic tendrils and leaves suspended in the opening and making it's way around the obelisk? A possibility would be to forge the branches from iron/steel and then grind smooth and have them chromed at a bumper shop. There would be contrast and you could cold connect the leaves and flowers. Talk about contrast! You mention "float", are you thinking of this being a kinetic piece? Movement could cause problems since chrome and most finishes do not stand up well when they are bumped against something hard like the cor-ten base. I am brainstorming and having fun thinking about this new project of yours. Thanks, Fred Zweig » reply Thanks Fred, I never
eligius1427 -
Wednesday, April 23, 2008 - 12:46am
Thanks Fred, I never considered chroming the piece and I think that would be a great look and contrast. When I used the term float I just meant that there wouldn't be obvious supports for the organic piece, not that it would be free to move around. Hopefully the end result will make the organic portion seem to just hover in the open space. When you mention cold connections for the leaves and flowers what did you have in mind? I'm not sure I would want to try to drill and tap that many holes in an undulating vine. Would chroming small/medium branches with the leaves and flowers welded on be an option? Then the branches could be cold connected into the final composition with fewer connections. I've never had anything chromed so I'm not sure how complicated the piece can be and still have a good result. I like this train of thought and appreciate your input. It's nice to have another opinion on a project so you don't get tunnel vision and miss an option, which I would of. Jake » reply  Jake, I'd suggest either the
Rich Waugh -
Wednesday, April 23, 2008 - 8:32am
Jake, I'd suggest either the stainless steel or silicon bronze. Both can be forged and welded easily, with no visible seams. Copper also, although it takes a bigger welder to work the copper as it conducts so readily. Likewise for forging it; you have to getg the whole piece up to forging heat, pretty much. The 300 series stainlesses forge pretty well at a high yellow heat, but get tougher to work as they cool. The work harden pretty quickly if worked cold, the same way non-ferrous metals do. If you go with the stainless, try to use only stainless steel wire brushes and dedicated grinding wheels with it, or you can contaminate it with steelparticles that foster rust. Stainless can be electgropolished after forging and welding to restore its "stainless" characteristics and shine it up. Or it can be left with firescale for a grey, iron-like finish. Silicon bronze is very strong, forges well hot, and be TIG welded with no color change at the joints. The cost is high, but the maintenance is low. You can join stainless steel to mild steel by using a high-nickel stainless electrode/wire such as 309 or 316L, and silicon bronze can be joined to mild steel using silicon bronze filler and a TIG or MIG welder. I would probably not opt for chroming mild steel as the service life is an unknown quantity and depends on the skills of the plater and the care it receives in use. Since both of those are factors outside your control, I think that caution dictates sticking with something that YOU control, like stainless or bronze. Aluminum would be a poor choice for mixing with mild steel, due to problems with galvanic corrosion. Those can happen when mixing stainless, copper or bronze with mild steel too, but to such a minor degree that I think you can safely ignore it. Particularly if the connections are welded. The 300 series stainless can be annealed the same way you anneal non-ferrous metals such as bronze or copper, by heating to cherry red and quenching in cold water. 400 series stainless, on the other hand, will harden if heated and quenched. If you end up deciding to use either stainless or bronze, I'd suggest that either one be polished and left natural after working and let nature take its course on the age patinas. The color change alone will be a nice contrast to the Cor-Ten or mild steel. If you wantg it to last pretty near forever and cost is no object, then I'd go with stainless steel for the obelisk and silicon bronze for the accents. No maintenance issues, no rust, and a good visual contrast between the two materials. » reply Thanks Rich for all of the
eligius1427 -
Thursday, April 24, 2008 - 11:49am
Thanks Rich for all of the information. Is there ever a problem with Chromium depletion between the hot and cold areas of the stainless during forging, resulting in less protection? Also, in your opinion, which do you think would be the easiest to work with for someone closer to the novice end of the spectrum in regards to forging? I really like the idea of the chrome, but you bring up a good point about losing an element of control. I feel like a kid in a toy store that can't decide what to do with his money:), too many options. Jake » reply Jake, If you like the idea
Rich Waugh -
Friday, April 25, 2008 - 1:30am
Jake, If you like the idea of the look of chrome, then go with the stainless steel. It can be polished to look very nearly like chrome, but it doesn't chip, flake, peel and rust like chrome will. Chrome plating is only good if done as triple chrome plating by very experienced platers, and it is limited by the surface finish of the underlyinng stgeel. So you would have to grind/polish the steel first, a very time-consuming job. The stainless, on the other hand, can be electropolished and look really good in short order. The time savings alone is huge and will more than offset the increased cost of stainless over mild steel. You don't have to worry about chrome depletion in the HAZ if you're using TIG welding, I don't think. Ifyou're concerned, you can solution anneal the piece after welding to re-form the chromium carbides. Rich » reply |
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ArtMetal
my limited experience of stainless
hi there my own limited experience of usimg stainless steel is to not heat it too high, you probably know this already, as it tends to work harden very quickly. I have had the steel just break off mid forging.!!! I made some stair carpet rods for a client from high grade stainless as the carpet in his house was worth £20,000 and did not want to mark it with rust.!! Scale does build up on the steel and you can use a number of things to remove it, i have used a combination of an acid used by welders to remove scale and blueing and stainless steel polishing pads and stainless wire cup brushes.
As for brasses i do not have any experience in that depatment, but i am sure that you will get a good few posts on this subject. Hope this is of some help just thought i would give you my limited experience of stainless and look forward to seeing some pictures or even the design proposal.
Adrian