Stainless Steel and Sheet Metal Fabrication: Are there Differences in the Methods?Blog | October 26th, 2018
Look at the fundamental differences that separate machine workable metal sheets and rigid stainless steel panels. Focusing on sheet metal fabrication, a ribbon of mild steel travels through a production line. A factory is using roll slitters to shear the ferrous-heavy metal into sized sheets. Hot rolled, pressed, and annealed, the iron is alloyed with carbon. For stainless steel panels, though, chromium alters the fabrication process.
Sheet Metal Machinability
Mild steel sheets are less than 6-mm thick. They’re loaded with carbon-reinforced strength. But, and here’s the important point, the added carbon doesn’t hamper machine workability. Mildy rigid and mildly tough, sheet metal can be bent and formed and welded with relative ease. Moving onto stainless steel, everything changes. Typically, the sheets are thicker than the 6-mm limit mentioned above. They’re plate sections, not thin sheets. Stainless steel has structural strength, plus a polished finish, which comes as a result of its naturally occurring chromium oxide coating.
Stainless Steel Workability Issues
Already, issues are making themselves known. There’s a 10.5% minimum of chromium in stainless steel, so products made from the alloy offer premium finishes, plus they’re highly corrosion resistant. Back at the workshop, however, the anti-corrosive alloy is creating problems. For cutting, especially hardened blades are fitted. The stainless metal gets hot because it’s hard, so a lubricant stream cools the cut zone. More worryingly, the chosen alloy is a member of the austenitic family. It work hardens easily, so the sawing process is managed. Duplex type stainless steel reacts in a similar way. Frankly speaking, machine shop equipment requires more raw power to process stainless alloys.
The Weldability Differences
Mild steels are welded all across the land, in every conceivable way, and under every kind of conditions. Oxy-acetylene cutters make short work of the job, as do arc welders. For stainless steel, well, the chromium and other trace metals added to this super-hard metal do readily expedite welding work. Just one problem, though, certain austenitic grades are crack sensitive. Lastly, although sheet metal cuts easily, cut stainless steel does not mirror this feature. Plasma arc cutters or heavy-duty laser cutting equipment are best employed when stainless plating needs cutting.
Mild steel is formed into shapes, cut to size, and bent so that the sheets precisely suit a stated application. Stainless steel plates are heavier and harder. Fabricated as plates, they’re used structurally or to seal vast amounts of fluid. Fuel tanks are an example of this build. Thicker plates of stainless steel create butcher blocks and architectural cladding, among other things. Ultimately, both forms of iron are worked in fabrication shops, but stainless steel machine work does require more energy and tougher tools.
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