# 4130 Tube Steel Alternatives?

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#### Turd Ferguson

##### Well-Known Member
HBA Supporter
Per inch on my screen for 4130. They don't list 1/2" tubes in DOM.
Which is another benefit of 4130, readily available in any size normally needed. Many sizes of 1020 from my local steel supplier requires a bulk order which is not practical.

#### BBerson

##### Light Plane Philosopher
HBA Supporter
Which is another benefit of 4130, readily available in any size normally needed. Many sizes of 1020 from my local steel supplier requires a bulk order which is not practical.
How much 1020 would you need to buy to get a price lower than 4130?

#### Armilite

##### Well-Known Member
This might be a different Chassis Shop, but it is priced per foot :

BJC
==========================================================

While I don't see the 4130 - 1/2" x .035 at the link provided, all of their other steel tube is Priced Per Inch, not by the Foot. So if it's .50 per inch, that's $6.00 a foot. OnlineMetals shows 4130 - 1/2" x .035$7.81 a foot.
Order Alloy Steel 4130 Tube in Small Quantities at OnlineMetals.com

Rich

#### Armilite

##### Well-Known Member
Some data I have collected.

4130 (Chromoly) Normalized Alloy Steel
Minimum Properties Ultimate Tensile Strength, psi 97,200
Yield Strength, psi 63,100
Elongation 25.5%
Rockwell Hardness B92

4130 (Chromoly) Annealed Alloy Steel
Minimum Properties Tensile Strength, psi 81,200
Yield Strength, psi 52,200
Elongation 28.2%
Rockwell Hardness B82

4340 (chromoly) Normalized Alloy Steel
Minimum Properties Ultimate Tensile Strength, psi 186,000
Yield Strength, psi 125,000
Elongation 12.2%
Rockwell Hardness B100

8620 (chrome-nickel-moly) Alloy Steel
Minimum Properties Tensile Strength, psi 97,000
Yield, psi 57,000
Brinell Hardness 201
Elongation 25%
Machinability 66%

1018 Mild (low-carbon) steel
Minimum Properties Ultimate Tensile Strength, psi 63,800
Yield Strength, psi 53,700
Elongation 15.0%
Rockwell Hardness B71

ASTM A36 Mild (low-carbon) steel
Minimum Properties Ultimate Tensile Strength, psi 58,000 - 79,800
Yield Strength, psi 36,300
1144 (Stressproof-equivalent) steel
Minimum Properties Ultimate Tensile Strength, psi 115,000
Yield Strength, psi 100,000
Elongation 8.0%
Rockwell Hardness B95 / C17
===============================================
2011-T3 Aluminum
Minimum Properties Ultimate Tensile Strength, psi 55,000
Yield Strength, psi 43,000
Brinell Hardness 95
Rockwell Hardness B60

2024-T3 Aluminum
Minimum Properties Ultimate Tensile Strength, psi 70,000
Yield Strength, psi 50,000
Brinell Hardness 120
Rockwell Hardness B75

5052-H32 Aluminum
Minimum Properties Ultimate Tensile Strength, psi 33,000
Yield Strength, psi 28,000
Brinell Hardness 60

6061-T6 Aluminum
Physical and Mechanical Properties Ultimate Tensile Strength, psi 45,000
Yield Strength, psi 40,000
Brinell Hardness 95
Rockwell Hardness B60

6063-T52 Aluminum
Minimum Properties Ultimate Tensile Strength, psi 27,000
Yield Strength, psi 21,000
Brinell Hardness 60

6101-T6 Aluminum
Physical and Mechanical Properties Ultimate Tensile Strength, psi 32,000
Yield Strength, psi 28,000
Brinell Hardness 71

6262-T6511 Aluminum
Minimum Properties Ultimate Tensile Strength, psi 31,900
Yield Strength, psi 27,600
Brinell Hardness 71

7075-T6 Aluminum
Physical and Mechanical Properties Ultimate Tensile Strength, psi 83,000
Yield Strength, psi 73,000
Brinell Hardness 150
Rockwell Hardness B87

#### Matt G.

##### Well-Known Member
Armilite-

What is the source of those allowables? What product form, thickness, specification, etc? A or B basis? All of those numbers are completely useless without that information. Also, I spot-checked a few of them, namely your numbers for 2024, 6061, and 7075. They don't match any reputable data that I have (MMPDS), and on top of that, they are unconservative, too...

#### Armilite

##### Well-Known Member
Armilite-

What is the source of those allowables? What product form, thickness, specification, etc? A or B basis? All of those numbers are completely useless without that information. Also, I spot-checked a few of them, namely your numbers for 2024, 6061, and 7075. They don't match any reputable data that I have (MMPDS), and on top of that, they are unconservative, too...
===================================================================================================

Dude:

I didn't pull them Numbers/Info out of my ass! I just Copied & Pasted the info, off their web site for my own use. Almost every Metal Site, gives the Spec's of the different metals they sell, and the Weights, in either Inch, or by the Foot. I don't remember which one I got those from, I use 4-5 different places to order Steel/Aluminium/etc. from. When Designing, Building Anything, you should always do your own research on the Material used!

Since probably 99.99999% of these Ultralight/Kitplanes ever built, are built with either 6061, the vast majority, or some with 4130 Tubing. His old Plans, called for 1/2" x .035" 1020, an even lower strenght metal than even 4130. If he wanted to use a different material than 1/2" x .035" 1020, like 6061, he would have to consult the Material Manuals. He would probably have to use something like 1/2" x .065" or .083" to achieve the same strenght as 1020. Since the vast majority of these Ultralight/Kitplanes were not Designed by any Engineers, and a lot were never even Stress Tested, some are over built. If something broke, or bent, it was made thicker!

Notice, these guys don't even carry 1020. I didn't even have it on my list.
Order Alloy Steel, Carbon, COLD ROLL, Mild Steel, STEEL HEX, Metal Pack, Plate, Rectangle, Round, Sheet, Square, Tube Alloys , 1018, 1045, 1144, 12L14, 4130, 4140, 4140/4142, 4142, 4330 VAR, 4340, 4340 VAR, 8620, 9310 VAR, A366/1008, A513, COLD ROLL

Guide to Buying Alloy Steel Online | Online Metals Guide to Selecting Metals for Your ProjectExample: The OnlineMetals Guide to (chromoly) Alloy Steel Chromoly is an abbreviation for "chromium-molybdenum steel". Chromoly is a range of low alloy steels used, for example, to produce tubing for bicycle frames and race-car roll cages. It is not as lightweight as aluminum alloys, but has the advantages of high tensile strength and malleability. It is also easily welded and is considerably stronger and more durable than standard (1020) steel tubing. Chromoly contains chromium but it does not have the corrosion resistance of stainless steel. 8620 is a triple-alloy carburizing steel with good toughness and ductility, increased hardness penetration, and hardneability to a strong, tough, core, with high case-hardness. Weldability is rated as excellent.
 4130 (chromoly) Alloy Steel (available in Round, Sheet, Tube) 4340 (chromoly) Alloy Steel (available in Round) 8620 (chromoly) Alloy Steel (available in Round)
 4130 (Chromoly) Normalized Alloy Steel Minimum Properties Ultimate Tensile Strength, psi 97,200 Yield Strength, psi 63,100 Elongation 25.5% Rockwell Hardness B92 4130 (Chromoly) Annealed Alloy Steel Minimum Properties Tensile Strength, psi 81,200 Yield Strength, psi 52,200 Elongation 28.2% Rockwell Hardness B82 Chemistry Iron (Fe) 97.3 - 98.22% Carbon (C) 0.28 - 0.33% Chromium (Cr) 0.8 - 1.1% Manganese (Mn) 0.4 - 0.6% Molybdenum (Mo) 0.15 - 0.25% Phosphorus (P) 0.035% max Sulphur (S) 0.04% max Silicon (Si) 0.15 - 0.35%
 4340 (chromoly) Normalized Alloy Steel Minimum Properties Ultimate Tensile Strength, psi 186,000 Yield Strength, psi 125,000 Elongation 12.2% Rockwell Hardness B100 Chemistry Iron (Fe) 96% Carbon (C) 0.37 - 0.43% Chromium (Cr) 0.7 - 0.9% Manganese (Mn) 0.7% max Molybdenum (Mo) 0.2 - 0.3% max Nickel (Ni) 1.83% Phosphorus (P) 0.035% max Sulphur (S) 0.04% max Silicon (Si) 0.23%
 8620 (chrome-nickel-moly) Alloy Steel Minimum Properties Tensile Strength, psi 97,000 Yield, psi 57,000 Brinell Hardness 201 Elongation 25% Machinability 66% Chemistry Carbon (C) 0.18 - 0.23% Manganese (Mn) 0.7 - 0.9% Phosphorus (P) 0.35% Max Sulphur (S) 0.4% Max Silicon (Si) 0.15 - 0.35% Chromium (Cr) 0.4 - 0.6% Nickel (Ni) 0.4 - 0.7% Molybdenum (Mo) 0.15 - 0.25% max
At OnlineMetals, we all failed shop class. Multiple times. As a matter of fact, our employment applications specifically ask to see people's grades for their high school shop classes. If they're too high, they go into the rejected pile. We're also not engineers, and cannot make any specific recommendations about the suitability of a given alloy, temper, or shape for your project or application. All technical data is for comparison purposes only and is NOT FOR DESIGN. It has been compiled from sources we believe to be accurate but cannot guarantee. This ends the part of the website that our pointy-headed lawyers made us put in.

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[h=1]AISI 1020 Low Carbon/Low Tensile Steel[/h][h=2]Topics Covered[/h]Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Machining
Weldability
Heat Treatment
Annealing
Carburizing
Core Refining
Case Hardening
Tempering
Normalizing
Stress Relieving
Applications [h=2]Introduction[/h]AISI 1020 is a low hardenability and low tensile carbon steel with Brinell hardness of 119 – 235 and tensile strength of 410-790 MPa. It has high machinability, high strength, high ductility and good weldability. It is normally used in turned and polished or cold drawn condition. Due to its low carbon content, it is resistant to induction hardening or flame hardening. Due to lack of alloying elements, it will not respond to nitriding. However, carburization is possible in order to obtain case hardness more than Rc65 for smaller sections that reduces with an increase in section size. Core strength will remain as it has been supplied for all the sections. Alternatively, carbon nitriding can be performed, offering certain benefits over standard carburizing.
AISI 1020 steel can be largely utilized in all industrial sectors in order to enhance weldability or machinability properties. It is used in a variety of applications due to its cold drawn or turned and polished finish property.
[h=2]Chemical Composition[/h]The chemical composition of AISI 1020 steel is:
ElementContent
Carbon, C0.17 - 0.230 %
Iron, Fe99.08 - 99.53 %
Manganese, Mn0.30 - 0.60 %
Phosphorous, P≤ 0.040 %
Sulfur, S≤ 0.050 %
[h=2]Physical Properties[/h]The physical properties of AISI 1020 steel are:
Physical PropertiesMetricImperial
Density7.87 g/cc0.284 lb/in³
[h=2]Mechanical Properties[/h]The mechanical properties of AISI 1020 steel are:
Mechanical PropertiesMetricImperial
Hardness, Brinell111111
Hardness, Knoop (Converted from Brinell hardness)129129
Hardness, Rockwell B(Converted from Brinell hardness)6464
Hardness, Vickers (Converted from Brinell hardness)115115
Tensile Strength, Ultimate394.72 MPa57249 psi
Tensile Strength, Yield294.74 MPa42748 psi
Elongation at Break (in 50 mm)36.5 %36.5 %
Reduction of Area66.0 %66.0 %
Modulus of Elasticity (Typical for steel)200 GPa29000 ksi
Bulk Modulus (Typical for steel)140 GPa20300 ksi
Poissons Ratio0.2900.290
Charpy Impact
Izod Impact125 J92.2 ft-lb
Shear Modulus (Typical for steel)80.0 GPa11600 ksi

[TD="align: left"]@Temperature -30.0 °C/-22.0 °F[/TD]
16.9 J
[TD]12.5 ft-lb
[/TD]
[TD="align: left"]@Temperature -18.0 °C/-0.400 °F[/TD]
18.0 J
[TD]13.3 ft-lb
[/TD]
[TD="align: left"]@Temperature -3.00 °C/26.6 °F[/TD]
20.0 J
[TD]14.8 ft-lb
[/TD]
[TD="align: left"]@Temperature 10.0 °C/50.0 °F[/TD]
24.0 J
[TD]17.7 ft-lb
[/TD]
[TD="align: left"]@Temperature 38.0 °C/100 °F[/TD]
41.0 J
[TD]30.2 ft-lb
[/TD]
[TD="align: left"]@Temperature 65.0 °C/149 °F[/TD]
54.0 J
[TD]39.8 ft-lb
[/TD]
[TD="align: left"]@Temperature 95.0 °C/203 °F[/TD]
61.0 J
[TD]45.0 ft-lb
[/TD]
[TD="align: left"]@Temperature 150 °C/302 °F[/TD]
68.0 J
[TD]50.2 ft-lb
[/TD]
[h=2]Machining[/h]In the cold drawn or turned and polished condition, AISI 1020 steel has high machinability. As per recommendations of machine manufacturers, AISI 1020 steel can be used for drilling, turning, milling and tapping operations using suitable feeds, tool type and speeds.
[h=2]Weldability[/h]AISI 1020 can be welded by performing the most common welding processes. In the cold drawn or turned and polished condition, it has better weldability. It has been suggested that the welding process should not be performed in heat treated or carburized condition.
[h=2]Heat Treatment[/h][h=2]Annealing[/h]AISI 1020 steel is heated at 870°C - 910°C followed by holding for certain time until the temperature remains constant all over the section. It is then cooled in a furnace.
[h=2]Carburizing[/h]AISI 1020 is heated to between 880°C - 920°C in a suitable carburizing atmosphere followed by holding for sufficient amount of time to produce the needed carbon content and case depth. After this, refining/hardening and tempering processes are carried out to optimize the core and case properties.
[h=2]Core Refining[/h]AISI 1020 steel is slowly cooled and re-heated at 870°C - 900°C followed by holding until the temperature remains constant all over the section and quenching in water, oil or brine.
[h=2]Case Hardening[/h]After performing the core refining process, it is re-heated to 760°C - 780°C followed by holding until the temperature is consistent all over the section. It is then quenched in water.
[h=2]Tempering[/h]AISI 1020 steel is re-heated at 150°C - 200°C followed by holding for certain time until the temperature remains constant throughout the section. It is soaked for 1 hour per 25 mm of section and then cooled under normal atmosphere. By performing the tempering process, the toughness of the case will be improved and grinding cracks will be reduced.
[h=2]Normalizing[/h]AISI 1020 steel is heated at 890°C - 940°C followed by holding until the temperature remains constant throughout the section. It is soaked for 10 - 15 minutes and then cooled in still air.
[h=2]Stress Relieving[/h]AISI 1020 steel is heated to 650°C - 700°C followed by holding until the temperature remains constant all over the section and soaking for 1 hour per 25 mm of section. It is then cooled in still air.
[h=2]Applications[/h]AISI 1020 steel is used in case hardened condition. The applications of AISI 1020 steel are:
• It is used for simple structural application such as cold headed bolts.
• AISI 1020 steel also finds use in the following components:
• axles
• general engineering parts and components
• machinery parts
• shafts
• camshafts
• gudgon pins
• ratchets
• light duty gears
• worm gears and
• spindles
Date Added: Jun 28, 2012 | Updated: Jun 11, 2013

#### Matt G.

##### Well-Known Member
Wow...TLDR.

No one in industry uses supplier data from the raw material manufacturer for strength allowables because they are generally optimistic at best. The other problem is they generally only list ultimate and yield tensile strength. The analysis of most aircraft structure is going to require a lot more data than that. Yes, I agree people need to do their own research, but I'd hate to see someone who doesn't know any better using incomplete and incorrect data that they stumbled upon in this thread when there is a comprehensive, conservative set of strength allowables available. You are free to do as you wish, but some of us would like to design an airplane that weighs only as much as it needs to and isn't carrying around a bunch of extra weight because we were too lazy to do any analysis or testing.

#### Chlomo

##### Well-Known Member
So it seems Aircraft Spruce and Wicks remain the premier choice of tubing materials.
At .57 per ft I couldn't believe my eyes.

#### PTAirco

##### Well-Known Member
AC&S do have a policy that they will match prices if you find a lower one. Try it. I never have in 15 years of buying stuff there itwas always the cheapest.

#### Victor Bravo

##### Well-Known Member
HBA Supporter
The OP asked about alternate materials to 4130. If memory serves, the original Piet plans called for Spruce instead of steel, and with careful sorting you can use Douglas Fir instead of Spruce per established aircraft practice.

I would, however, substitue a glue gun for a welding torch

As far as welded tube, the resale value of the aircraft, the "sleep soundly" factor for all concerned, and the general acceptance within the homebuilt aviation community... all strongly favor 4130. Another thing nobody has mentioned is that the quality control that comes with 4130 seamless is probably a lot better and more reliable than the quality control of the other "hardware store" grades of steel tube.

If 4130 was 2X or 3X more expensive, then this would be something to discuss. But if the airplane quality tube is anywhere close to the cost of the other stuff, it's pretty obvious what the better overall choice is. Seems to me like this is a good example of the established conservative "old standby" being better than getting too creative.

Especially on a Pietenpol, where there is no really significant need or gain to go into the exotic.