Mild steel instead of 4130?
Wee Moose
problem with using mild steel instead of 4130? I would make all fittings and
high stress areas, like gear, with 4130.
Carl
Russell & Jillian Millar
I'm sure someone will correct me if I'm wrong about this but I believe
you will find mild steel rusts considerably quicker than 4130.
Considering the amount of work that goes into a project like a plane is
it worth the couple of bucks you would save. Or is there another reason
for using mild steel?
--
Cheers
Russell
hamst...@my-deja.com
> I know many older planes were made with mild steel
> tubing. What would be the problem with using mild
> steel instead of 4130? I would make all fittings and
> high stress areas, like gear, with 4130.
I think that you wouldn't save much money, and that you'd likely end up
with a much heavier airplane.
The 'mild' steel that was used in those earlier aircraft to which you
allude was for the most part SAE 1020. I think that these days, supply
and demand being what it is, 1020 tends to be just as expensive as
4130, and often more so. Highflyer made some good points in this
earlier post on a related topic:
http://x53.deja.com/getdoc.xp?AN=526384987
and I quote:
> However, since there is no difference in weight
> or stiffness between 1020 series steel and 4130
> series steel and the only obvious difference is
> in strength, and in the small quantities we buy
> aircraft tubing, there is no difference in cost,
> why NOT use 4130. It is, indeed, overkill, but
> it is basically free.
Follow that thread above back for some more interesting stuff.
As for going down to your local steel supply house and buying a bunch
of garden-variety steel tube, what you'll find is a decided lack of
choices when it comes to sizes. For the most part, your choices of ODs
will be in 1/4" increments, like 1/2", 3/4", 1", and etcetera. And,
even worse, your choices of wall thicknesses will be even worse - for
the most part you'll find yourself limited to 1/16" and 1/8". As
regards steel tube airframes, those thicknesses are both much, much
heavier than is used for most members.
On the other hand, 4130 comes in an incredible variety of shapes and
sizes. In the Spruce catalog, there's over 130 different combinations
of ODs and wall thicknesses listed - and that's just the round tubes.
There's also another couple dozen squares, rectangles, and streamlines.
I'm not an expert by any stretch, but what I've seen of standard
practice in steel tube airframes is that you try to use the thinnest
wall stuff possible, and try to size the OD of the tube to the loads
imposed. That maximizes stiffness and strength per pound of steel. What
you end up with is having the majority of members .035" wall, with some
thicker sections where necessary. If you limited yourself to the
nearest matching size of commercial steel, your airframe would likely
weigh from 70% to 100% more than if it were made of 4130.
Or at least that's my semi-informed opinion.
Hammy
Sent via Deja.com http://www.deja.com/
Before you buy.
Charles K. Scott
"BRO" <brog...@kewl.com.au> writes:
> being less "brittle/stiff" (technical terms here) when a friend came a
> cropper in his homebuilt the mild steel folded absorbing enough of the
> impact to save his life.
I always thought "came a cropper" meant someone had died. It comes
from pushing up crops.
Corky Scott
highflyer
>
> I know many older planes were made with mild steel tubing. What would be the
> problem with using mild steel instead of 4130? I would make all fittings and
> high stress areas, like gear, with 4130.
>
Back in the thirties and forties many aircraft used 1020 "mild" steel
tubing for much of the structure where the loads were relatively low.
1020 steel has the identical stiffness and weight as 4130, but only
about half the yield strength.
As a result the only reason to utilize 1020 rather than 4130 is to
save some money on the cost of the tubing. Economies of scale have
changed in the last sixty years. In todays market aircraft grade
1020 tubing is very hard to find. When you do find it, it costs as
much or more than aircraft grade 4130. As such, the only valid
reason for substituting 1020 for 4130 is gone.
Since you can even use 4130 to repair a 1020 structure with no change
other than a strength increase, 1020 has fallen out of use, even for
the factories who still build with steel tubing.
--
HighFlyer
Highflight Aviation Services
highflyer
>
> Interestingly enough Mild steel has some distinct advantages when you crash
> test the aircraft.
>
> being less "brittle/stiff" (technical terms here) when a friend came a
> cropper in his homebuilt the mild steel folded absorbing enough of the
> impact to save his life.
>
SAE 1020 and SAE 4130, and indeed ALL steel alloys, have the same
"Young's
Modulus" which is a measure of the stiffness of the steel. This factor
is primarily determined by the base metal in the alloy, rather than by
the relatively small contribution made by the alloying elements.
4130 and 1020 have approximately identical "damage absorbion"
characteristics. The increased toughness of the 4130 means that you
are less likely to have the tubing rupture and tear giving rise to
possible injury.
The only valid reason to substitute 1020 for 4130 is cost, and that
difference no longer applys.
Rich Shankland
news:3A30F31C...@alt.net...
>
> SAE 1020 and SAE 4130, and indeed ALL steel alloys, have the same
> "Young's
> Modulus" which is a measure of the stiffness of the steel. This factor
> is primarily determined by the base metal in the alloy, rather than by
> the relatively small contribution made by the alloying elements.
>
> 4130 and 1020 have approximately identical "damage absorbion"
> characteristics. The increased toughness of the 4130 means that you
> are less likely to have the tubing rupture and tear giving rise to
> possible injury.
>
> The only valid reason to substitute 1020 for 4130 is cost, and that
> difference no longer applys.
>
I remember machining a replacement stub axle for a friend's boat trailer
using 1020. When we lowered the jack, the axle slowly bent up until the tire
rested on the side of the boat. We made another from 4130 and it worked fine
for years, even without heat treatment.
--
Rich Shankland
http://www.harbornet.com/folks/shankland/emeraude.html
http://www.spamcop.com
3 confirmed kills
KJKimball
is what is shown in many of the old airplane blueprints I have seen. 1025 is
not available any longer and while it may not be extremely different than
1020, it is different and I don't think you can use 1020 as a replacement for
1025 only equal to or better like 4130 is. In the Boeing Model 75, aka
stearman Kaydet prints as well as Beech Model 17 Staggerwing prints, 4130 is
spec'd. with NE(national emergency)steel tube be acceptable in war emergencies.
NE tube is shown to meet the same minimum strengths of 4130 yet can be a
seamed tube. 1025 and 4130 tube for aircraft are seemless tube. Refer to the
manual, "Aircrafdt Tubing Data" by Younger for Summerill Tubing Co.
Kevin
Bruce A. Frank
difference in the price of mild steel tube (1018,1020) and 4130. We have
had a discussion here before about building with electrical conduit. Now
that is cheap.
Russell & Jillian Millar wrote:
>
> Wee Moose wrote:
> >
> > I know many older planes were made with mild steel tubing. What would be the
> > problem with using mild steel instead of 4130? I would make all fittings and
> > high stress areas, like gear, with 4130.
> >
> > Carl
>
> I'm sure someone will correct me if I'm wrong about this but I believe
> you will find mild steel rusts considerably quicker than 4130.
> Considering the amount of work that goes into a project like a plane is
> it worth the couple of bucks you would save. Or is there another reason
> for using mild steel?
>
> --
> Cheers
> Russell
--
Bruce A. Frank, Editor "Ford 3.8/4.2L Engine and V-6 STOL
BAFRANK(at)worldnet.att.net Homebuilt Aircraft Newsletter"
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While trying to find the time to finish mine.
ProCareJax
1020...and 1025 is... 1025 has a 5% ma(n)genese (sp?) added to the
alloy...stronger...but...good or bad..I dont know. 1020 is a mild carbon steel
and doesnt rust as quick..but has less strength. Mild 1020/25 mild steel IS
easier to gas weld than 4130...but dont let that be a deterent for using 1020.
4130 is superior in every respect..including price.
Hope this helps,
Dave
padre...@gmail.com
> I know many older planes were made with mild steel tubing. What would be the
> problem with using mild steel instead of 4130? I would make all fittings and
> high stress areas, like gear, with 4130.
>
> Carl
weight puddle-around aircraft there just is no contest!