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Steel vs Stainless steel

S

STEEL

Registered User
Hi,
I am building a scratch PA-18.
Most of the internal wing fittings (not spars or ribs) call for 1025 Steel for the parts (Northland plans).
I am drawing most of these in CAD and then laser cutting.
Would there be a benenfit in cutting out of Stainless Steel?
No need to paint or powdercoat to prevent corrosion afterwards.
What do you guys think?
Thanks,
Neal.
 
I'd suggest check the static strength, notch sensitivity, and fatigue properties of the stainless grade you have in mind, and compare to 1025.
 
The Delorean approach to building a Super Cub.

I think it wouldn't take long before you went back to 4130 for all of the steel parts. Most alloys of stainless are not so easy to weld, more difficult to machine and much more expensive. I can't see any advantage to using stainless steel in lieu of chrome-moly. CM steel can be painted, coated and plated easily to prevent any corrosion issues.
 
I guess that's no problem, some grade stainless steel's profermance much better than 1025,but careful welding is needed.In China,its hard to find 1025 filmy steel plate,I plan made wing small parts(unimportant parts) and fuselage decorative parts in stainless steel
 
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The parts I was thinking of replacing are not for welding, mostly bolted or riveted.
Like for aileron and flap hinges and brackets, drag wire brackets, etc.
I live in South Africa and steel and Stainless steel are more readily available then 4130.
 
isn't there also something about stainless being LESS strong than 4130, so you could build what ever stronger/thiner/lighter with 4130 then... and get same strength to accomplish job???
 
Last year we started switching our self unloading hopper truck bodies from steel construction to Stainless steel. We have several in use now. We love them for the corrosion proof qualities, but they havent been trouble free. The early ones started showing some stress cracking in the welds and joints. We had to put some reinforcing gussets in some spots. They do a lot of twisting when off road. The weight difference between regular and the stainless ones are not much, but it seems to point out the stainless ones need to be thicker to stand the same stress as the regular steel so the next ones will probably weigh more.

jim

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The specific gravity of all alloys varies a bit but they're all close to .280 pounds per cubic inch.
 
I was told by one mechanic that SS is 17% less strong then steel.

Losing 15% of strength would be a serious concern
 
aktango58 said:
I was told by one mechanic that SS is 17% less strong then steel. Losing 15% of strength would be a serious concern
Click to expand...
Not necessarily. It is necessary to read and understand the mechanical properties specifications for both the alloy and its furnished condition.
 
I bought this rig from a family owned metal fabrication business in Wisconsin this year. They do mostly stainless work at dairy and food processing plants. The crane and Mack truck were bought new, separately, and they mounted it up and then had it certified. So.....what isn't aluminum deck plate is all stainless steel, even the framing under the rigging boxes, all stainless! It gets interesting responses, most people don't notice or care, but any one who has been around metal fab work does a double take! This glamour shot is what I use on my business card. I love the way I no longer have to worry about scratching the paint on the side rails, and the seller really seemed to appreciate I fully got the uniqueness of it.
 
As mentioned above, there are many different stainless alloys with many differing properties than 4130. Some are stronger than non heat treated 4130 and some are not.
One very important difference would be the tendency to work harden as the material flexes.
Some stainless alloys work harden and become brittle VERY quickly. Once this happens the part is prone to cracking, and sudden failure.
So an alloy that is listed as ductile, may become brittle with use (not ideal for aircraft)
Please be very careful substituting stainless steel for aircraft parts.
 
What bda said...
Stainless has such a wild variation af strength/ductility depending on type. You would want to have a very accurate assessment of static/dynamic load variations on every single partin order to accurately determine the suitable stainless equivalent to 4130. And then a good background in metalurgy to pick which type of SS to use.
Chromoly on the otherhand is one type of steel with known quantities and characteristics. For the price of primer and paint I would stick with a known entity.
 
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