tubing comparison

[MILLER]

Passing on some info I found today.

CARBON CONTENT: " The last two numbers in the S.A.E. numbers always indicates the carbon content of the steel in hundredths of one percent. This would mean that S.A.E. 1010 would have .10% carbon content and 1020 would have .20% carbon content."


1010 specs out at: (%)

C .08-.13
Mn .30-.60
P .035 max
S .035 max

For CREW/HREW:

Tensile strength (ksi) 55
Yield point (ksi) 40
Elongation (% in 2") 20
Rockwell hardness RB60


1020 specs out at: (%)
C .15-.25
Mn .30-.60
P .040 max
S .050 max

For HREW/CREW then DOM

Tensile strength (ksi) 80
Yield point (ksi) 70
Elongation (% in 2") 15
Rockwell hardness RB80

Notice that the average carbon content is .20% for 1020 and .10% for 1010?

As Carbon Content is increased (within limits), Tensile strength increases, but Ductility decreases. For Example, a normal everyday piece of low carbon flat bar, usually A-36 with a carbon content of .26-.28% - you can put one end in a vise and wobble its other end without deforming the metal. This is demonstrating its elasticity. Yet you can bend it just by applying enough force. At the point that it starts to permanently deform, I.E. bend is the point that it has reached its elastic limit, which would also be its yield strength. If you bend it tight enough or apply enough force the section will start to narrow and stretch out. This is demonstrating its ductility. If you apply even more force, the metal will stretch enough that it breaks or fractures. This is demonstrating the tensile strength. Basically as Carbon Content increases, the tensile and yield strength increases, but the zone between yield and tensile narrows. Take the same size of a piece of high carbon steel such as a file, which would have a carbon content of approx. 1.2-1.3% and try to bend it. Would not happen, you could only break it with the application of a much larger force than required to bend the flat bar as it’s tensile and yield strength would be much higher than the flat bar but the difference between tensile and yield would be much smaller. This is a much better demonstration in a shop with a file and a chunk of flat bar.


Basically there are 2 factors contributing to 1020 DOM strength increase: Carbon Content as well as the cold working of the metal through the DOM process.

As far as bending ease, you should be looking at the yield strength #'s, as when you are cold bending tube you are taking it past it's elastic limit in order to change it's shape. Given the same OD and wall thickness, it is going to be harder to bend 1020 DOM than 1010 HREW. look at this thread, some additional information is included that might clear things up: http://www.pirate4x4.com/forum/showt...threadid=12322

[MILLER]

from what I have found, structural pipeis about the same strength as HREW but DOM is still almost twice as strong as either.

[Fonger]

Link no worky...

[Billet Benny]

http://www.pirate4x4.com/forum/showpost ... stcount=22



Every kinda of whatever made is gonna be made of different materials and processes.. These are what's important in a tube's characteristics and strengths. Pipe, while often made of lower tensile strength steel is often a little more comparable with DOM in strength given typical tube wall thicknesses are .120" while pipe thicknesses in similar OD are greater and sometimes even twice as much. In the end this becomes a huge weight issue and pipe is still pipe.. And there's so many different grades and types of pipe out there you better know what you're getting if you decide to use it. At the same time, buying and using 1010 tube may be cheap, but it's also damn weak stuff itself. There's a reason it makes sense to use at least DOM for almost all projects.

Jason, you should already know backwards and forwards everything you posted.. You are an ME graduate. Why copy and post common information?

[yotacowboy]

moral of the story:

for bumpers and sliders: use 1020 HREW

For cages, chassis parts (crossmembers, skidplate structures, mounts) and for STRONGER bumpers and sliders: use 1020 DOM

For Benny: use 4130 seamless

For Dibble: use 2" dia. 300m solid round stock, gun-drilled

For plumbers: use pipe

[yotacowboy]

from what I have found, structural pipe is about the same strength as HREW

mmmmmm... not true. you're dealing with heavier wall thicknesses (and an increase of almost .75 pound per foot of material with similar outside diameters, 1.95" and 2.0", respectively) and for pipe, looser dimensional tolerances.

1.5" SCD40 /= 2" .120 wall HREW

1.5" SCD40 /= 2" .120 wall HREW

1.5" SCD40 /= 2" .120 wall HREW

1.5" SCD40 /= 2" .120 wall HREW

(how many times is this going to be covered?)

The next issue is that unless you're willing to buy pipe dies for a bender, you'll be using a cheapo HF bottle jack pipe-kinker to do anything other than straight parts with mitered joints. this is less than desireable.

so to save a few bucks, you've used a slightly weaker material, added noticeably more weight to the vehicle, and fabricated the structure using less than optimal cold working methods. you've also turned your rig into a hack-ass pile of shit.

So one more time from the top:

Pipe is cheap

Pipe is heavy

Pipe is hack-ass

Put down the pipe.

[Billet Benny]

(how many times is this going to be covered?)

It'll never end..

Miller,
What you have quoted are MATERIAL strengths.. That's a part of a round section's strength, but the rest is that nerdy engineering term "I" (Area moment of inertia) and things like that depending on how the tube is loaded. So we have no indication of the tube or pipe's real life strength till we take into account od and wall thickness (aka id) along with the material's properties.

[Steinberg]

the difference in ultimate tensile strength for the two data sets listed up there should be mostly due to the carbon content, not the DOM process. the cold-working associated with the DOM process does increase the yield strength though, and that's what's of most interest in what we're building.

now for 10 extra gay-points, can anyone explain why cold-working (a.k.a. strain hardening) increases the yield strength of a material?

[MILLER]

Well, I was discussing with someone the strength differences between HREW and DOM, I didnt know off hand (ME degree from Tech doesnt mean donkey dick), I looked it up and decided to share the information. And the post about structural pipe is from someone elses comment on another thread stating structural pipe is similar in material strength to HREW, that spiked my interest and I looked it up, and relayed what I found.

[MILLER]

[quote="Billet Benny"
It'll never end..

Miller,
What you have quoted are MATERIAL strengths.. That's a part of a round section's strength, but the rest is that nerdy engineering term "I" (Area moment of inertia) and things like that depending on how the tube is loaded. So we have no indication of the tube or pipe's real life strength till we take into account od and wall thickness (aka id) along with the material's properties.[/quote]

Oh, yeah, tensile strength, thats the amount of force put on a material sample, loaded in tension, until it stretches so far it breaks. THAT is the point of the thread, to give an idea what the material differences in the different types of tubing are. Granted yield strength (amount the material stretches before plastic deformation) is probably the better comparison.

[MILLER]

now for 10 extra gay-points, can anyone explain why cold-working (a.k.a. strain hardening) increases the yield strength of a material?

It binds all the little steel microstructures together and increase their resistance to slipping along one another.

[Billet Benny]

Oh, yeah, tensile strength, thats the amount of force put on a material sample, loaded in tension, until it stretches so far it breaks. THAT is the point of the thread, to give an idea what the material differences in the different types of tubing are. Granted yield strength (amount the material stretches before plastic deformation) is probably the better comparison.

Here's my point. HREW is not always 1010, DOM is not always 1020, and the same for pipe.. You've quoted particular materials for each kind of tube and that's not right because they can be made of ANYTHING. HREW can be 1030 and so can DOM.. Pipe can be some funny as chromium-molybdenum alloy for some application and so could DOM. The point is there's no true actual comparison of DOM, HREW, and pipe until you make them of the same material and the same size. If you want to compare materials then why even bring in the word tube, pipe, etc.? If you want to compare HREW to DOM that's fine, but for a comparison it takes more than just picking a random material for one and a random material for the other. Sure DOM is more often found as a better grade of steel, and that's one of the advantages of using it for everything. Compare 1010 HREW to 1020 DOM... ok for one comparison.. but that's not the end of the story as that's only one of many many materials you can find it made from. So you can't make the blanket statement "pipe is the same strength as hrew and dom is twice as strong as both."

[Billet Benny]

Granted yield strength (amount the material stretches before plastic deformation) is probably the better comparison.

Yield strength is the amount of stress the matertial can handle before it plastically deforms. Has nothing to do with strain.

[Steinberg]

now for 10 extra gay-points, can anyone explain why cold-working (a.k.a. strain hardening) increases the yield strength of a material?

It binds all the little steel microstructures together and increase their resistance to slipping along one another.

not quite... the microstructure doesn't change significantly unless it's heated and cooled.

[MILLER]

arrrggggh. I didnt say anything about changing the microstructure. Do some more FEA.