Materials Database

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Subzero's Materials (250lber)

This is a brief database of useful properties for commonly used materials within battlebots as well as some background information and peoples' experience working with them. Some material properties have not been included but feel free to add anything important. Material properties usually vary slightly for a given material from vendor to vendor so in the majority of cases, trust specs given by the manufacturer or supplier over the specs in this database when they are given. In addition, some of these material properties can vary slightly depending on the data source and also other details such as heat treatment and the kind of sample the material data was acquired from.

Steels

Steels are strong, dense, iron-carbon alloys which come in a variety of material compositions and treatment standards. A variety of major and minor alloying elements are added to improve certain material properties, including strength, toughness, corrosion resistance, or machinability. When selecting a grade of steel to use for your robot, consider how the material properties of the steel address the design requirements. Listed below are some more common grades of steel:

Abrasion-Resistant (AR) Steel

"AR" Steel, or "Abrasion Resistant" Steel is a high-strength, low carbon hardened alloy designed to resist wear and stress. The "grade" of the abrasion-resistant steel correlates to the Brinell hardness rating.

AR500 Steel

Type Carbon Steel
Modulus of Elasticity 30,000 ksi
Poisson's Ratio 0.29
Density 0.29 lb/in^3
Ultimate Tensile Strength 225 ksi
Tensile Yield Strength 200 ksi
Brinell Hardness 450 HB
Rockwell Hardness C47-48
Elongation at Break 12%
Charpy Impact (V-notch) 24.4J
Familiar Sellers McMaster Carr, MakeItRingTargets, Alro Steel, SendCutSend

Material Description:

  • High strength, high hardness, abrasion resistant steel used in body armor and shooting targets
  • Generally considered to be tougher than S7 tool steel but has lower hardness
  • Hardened steel is very difficult to machine, is typically only used for Waterjet parts
  • No further heat treatment needed
  • Typically used for weapons and wedges due to it's high strength, toughness, and relatively high hardness
  • Used more commonly as armor in higher weight classes
  • Anecdotal experience from builders says that AR500 typically bends before it fractures
  • Will rust over time when wet or exposed to air

AR400 Steel

Type Carbon Steel
Modulus of Elasticity XX ksi
Shear Modulus XX ksi
Poisson's Ratio XX
Density XX lb/in^3
Ultimate Tensile Strength XX ksi
Tensile Yield Strength XX ksi
Fracture Toughness (Riobotz Sample) XX ksi-in½
Calculated Toughness XX J/in^2
Charpy Impact (V-notch) ~XX J
Brinell Hardness XXXX HB
Rockwell Hardness CXX
Elongation at Break ~XX%
Familiar Sellers McMaster, Online Metals

Tool Steel

Unlike abrasion-resistant or carbon steels, tool steels are specialized grades of steel used primarily for tool production and cutting bits. Added alloying elements such as Cr, V, Co, W, or Mo are added to greatly increase the strength and wear resistance of the steel, but tool steels tend to be more expensive than standard carbon steels.

S7 Tool Steel (at 54 HRC)

Type Carbon Steel
Modulus of Elasticity 30,000 ksi
Shear Modulus 11900 ksi
Poisson's Ratio 0.29
Density 0.282 lb/in^3
Ultimate Tensile Strength 284.9 ksi
Tensile Yield Strength 220.4 ksi
Fracture Toughness (Riobotz Sample) 50.0 ksi-in½
Calculated Toughness 9.42 J/in^2
Charpy Impact (V-notch) 16.3 J
Brinell Hardness 543 HB
Rockwell Hardness C54
Elongation at Break 6.5%
Familiar Sellers McMaster Carr, OnlineMetals
  • Shock resisting tool steel that has high strength and high impact toughness
  • Usually used in weapons but has been used by some NHRL builders for shafts but with hardnesses much lower than 54 HRC
  • Is machined in its annealed form and then heat treated, quenched, and tempered to exactly 54 HRC which is a value recommended by the Riobotz Combot Tutorial pg 59-60.
  • Ray Billings, builder of Tombstone, also endorses exactly 54 HRC for S7
  • Anecdotal experience from other builders shows it fails through fracture before bending
  • Considered to be less tough than AR500 and is commonly used when the higher hardness (C54 vs C48) is desired like for weapon teeth
  • Extra important to avoid sharp internal corners and stress concentrations to prevent cracks from forming

AISI Alloy Steels

(description here)

AISI 4340 (43 HRC)

Type Carbon Steel
Modulus of Elasticity 29,732 ksi
Shear Modulus 11900 ksi
Poisson's Ratio 0.29
Density 0.283 lb/in^3
Ultimate Tensile Strength 210.0 ksi
Tensile Yield Strength 194.9 ksi
Fracture Toughness (Riobotz Sample) 80.1 ksi-in½
Calculated Toughness 24.38 J/in^2
Charpy Impact (V-notch) ~19 J
Brinell Hardness 402 HB
Rockwell Hardness C43
Elongation at Break ~9.6%
Familiar Sellers McMaster, Online Metals
  • Ultra high strength steel that is machined in its annealed state and is heat treated by quenching and tempering it to a desired hardness.
  • Riobotz's recommended hardness for shafts is 40-43 HRC which will allow it to fail by bending before breaking
  • Is often used by some builders for other parts such as beaterbars at higher hardnesses
  • Relatively expensive

AISI 4140 (-- HRC)

Type Carbon Steel
Modulus of Elasticity XX ksi
Shear Modulus XX ksi
Poisson's Ratio XX
Density XX lb/in^3
Ultimate Tensile Strength XX ksi
Tensile Yield Strength XX ksi
Fracture Toughness (Riobotz Sample) XX ksi-in½
Calculated Toughness XX J/in^2
Charpy Impact (V-notch) ~XX J
Brinell Hardness XXXX HB
Rockwell Hardness CXX
Elongation at Break ~XX%
Familiar Sellers McMaster, Online Metals

Aluminum Alloys

Aluminum Parts

Aluminum 6061-T6

Type Aluminum Alloy
Modulus of Elasticity 10,000 ksi
Shear Modulus 3800 ksi
Poisson's Ratio 0.33
Density 0.0984 lb/in^3
Ultimate Tensile Strength 45 ksi
Tensile Yield Strength 39 ksi
Fracture Toughness (T-L dir) 26.4 ksi-in½
Calculated Toughness 7.88 J/in^2
Charpy Impact Test (V-notch) 21.7 J
Brinell Hardness 93 HB
Rockwell Hardness B52
Elongation at Break 10%
Machinability (Vs. 1112 Steel) 270%
Familiar Sellers McMaster Carr, Midwest Steel Supply, SendCutSend

Material Description:

  • Lightweight aluminum alloy that comes already pre-heat-treated T6 temper which gives it its strength
  • Beware of tempers T4 and O which are weaker than 6061-T6
  • Typically used for frame rails, plates, pulleys, and armor for some bots
  • Tends to fail in bending before fracturing
  • Tends to "ablate" and may take gashes when hit directly by weapons
  • Easy to machine and relatively cheap

Aluminum 7075-T6

Type Aluminum Alloy
Modulus of Elasticity 10,000 ksi
Shear Modulus 3800 ksi
Poisson's Ratio 0.32
Density 0.102 lb/in^3
Ultimate Tensile Strength 81 ksi
Tensile Yield Strength 69 ksi
Fracture Toughness (T-L dir) 22.8 ksi-in½
Calculated Toughness 5.87 J/in^2
Charpy Impact Test (V-notch) 5.4 J
Brinell Hardness 150 HB
Rockwell Hardness B87
Elongation at Break 7.9%
Machinability (Vs. 1112 Steel) 170%
Familiar Sellers McMaster Carr, Midwest Steel Supply, SendCutSend

Material Description:

  • Aerospace grade aluminum alloy which is much stronger and harder than 6061-T6
  • Pre-heat-treated to T6 temper
  • Past and anecdotal experience notes that it tends to fracture before it bends as it's more brittle than 6061
  • Some builders recommend avoiding using it as armor or for parts that take direct hits due to fracture risk
  • Relatively easy to machine
  • More expensive than 6061-T6

Aluminum 5052-H32

Type Aluminum Alloy
Modulus of Elasticity XX ksi
Shear Modulus XX ksi
Poisson's Ratio XX
Density XX lb/in^3
Ultimate Tensile Strength XX ksi
Tensile Yield Strength XX ksi
Fracture Toughness (T-L dir) XX ksi-in½
Calculated Toughness XX J/in^2
Charpy Impact Test (V-notch) XX J
Brinell Hardness XX HB
Rockwell Hardness BXX
Elongation at Break XX%
Machinability (Vs. 1112 Steel) XX%
Familiar Sellers McMaster Carr, Midwest Steel Supply, SendCutSend

Material Description:

Aluminum 2024-T6

Type Aluminum Alloy
Modulus of Elasticity XX ksi
Shear Modulus XX ksi
Poisson's Ratio 0.XX
Density XX lb/in^3
Ultimate Tensile Strength XX ksi
Tensile Yield Strength XX ksi
Fracture Toughness (T-L dir) XX ksi-in½
Calculated Toughness XX J/in^2
Charpy Impact Test (V-notch) XX J
Brinell Hardness XX HB
Rockwell Hardness BXX
Elongation at Break XX%
Machinability (Vs. 1112 Steel) XX%
Familiar Sellers McMaster Carr, Midwest Steel Supply, SendCutSend

Material Description:

Other Metal Alloys

Grade 5 Titanium (Ti-6Al-4V)

Type Titanium Alloy
Modulus of Elasticity 16510 ksi
Shear Modulus 5800 ksi
Poisson's Ratio 0.32
Density 0.160 lb/in^3
Ultimate Tensile Strength 138-150 ksi
Tensile Yield Strength 128-140 ksi
Fracture Toughness (Annealed Plate) 67.9 ksi-in½
Calculated Toughness 31.5 J/in^2
Charpy Impact Test (V-notch) 17 J
Brinell Hardness 310 HB
Rockwell Hardness C34
Elongation at Break 6.7%
Machinability (Vs. 1112 Steel) 20%
Familiar Sellers McMaster Carr, SendCutSend, TMS Titanium

Material Description:

  • Very high strength and high toughness metal alloy
  • Denser than aluminum but less dense than steel. May destroy tools if you're not careful
  • Typically sold and used in its annealed state for high toughness. No heat treatment needed.
  • Typically used for armor, structural plates, sometimes weapons, it's pretty versatile material overall
  • Known to fail in bending before failing in fracture
  • Very expensive, more so than most steels and aluminum alloys
  • Very difficult to machine or drill due to work hardening properties
  • In some cases, outsourcing to SendCutSend might be financial preferable to buying Ti stock so discuss with your PM

Plastics and Polymers

Plastics and other polymerized materials are significantly less dense than metals, and are generally more machinable or formable.

Ultra-High-Molecular-Weight-Polyethylene (UHMW)

High-Density-Polyethylene (HDPE)

Polycarbonate

Carbon Fiber

Acrylonitrile Butadiene Styrene (ABS)

Polylactide Plastic (PLA)

Thermoplastic Polyurethane (TPU)

Sources

  • AR400 Steel:
    • source
  • AISI 4140 Steel:
    • source
  • Al 5052-H32:
    • source
  • Al 2024-T6:
    • source
  • UHMW:
    • source
  • HDPE:
    • source
  • Polycarbonate:
    • source
  • Carbon Fiber:
    • source
  • ABS:
    • source
  • PLA:
    • source
  • TPU:
    • source

Notes

  • The charpy impact data provided by Team Caustic Creations was "quick and dirty" and was hard to verify
    • They didn't specify how they got the data and where from
    • Their value for Ti-6Al-4V was off from the Matweb data page so take it with a grain of salt
    • Charpy impact data is pretty hard to find. It might be worth it for RoboJackets to our own Charpy impact tests
  • The Plastics and Polymers section does not distinguish the material property differences between machined stock pieces and extruded 3D prints. Because of the layer-by-layer extrusion of 3D printers, it is vital to note that the material strength is directionally dependent, and depends on the infill style and percentage infill.