Glenn

1018 vs A 36 steels, and CR vs HR

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Originally posted by jlpservices in another thread.

 

1018 comes in both Cold rolled (CR) and hot rolled (HR)..  CR has a high tensile strength than HR it also works a little bit differently even when hot.. 

CR comes in 12ft lengths and HR comes in 20ft lengths.. CR usually costs more than HR..

A36 here usually fills the Niche sizing types..   

1018 is much more forgiving to heat cycling and improper forging techniques vs A36..   It also forge welds at a different temperature.. 

 

Introduction

AISI 1018 mild/low carbon steel has excellent weldability and produces a uniform and harder case and it is considered as the best steel for carburized parts. AISI 1018 mild/low carbon steel offers a good balance of toughness, strength and ductility. Provided with higher mechanical properties, AISI 1018 hot rolled steel also includes improved machining characteristics and Brinell hardness.

Specific manufacturing controls are used for surface preparation, chemical composition, rolling and heating processes. All these processes develop a supreme quality product that are suited to fabrication processes such as welding, forging, drilling, machining, cold drawing and heat treating.

Chemical Composition

Element Content
Carbon, C 0.14 - 0.20 %
Iron, Fe 98.81 - 99.26 % (as remainder)
Manganese, Mn 0.60 - 0.90 %
Phosphorous, P ≤ 0.040 %
Sulfur, S ≤ 0.050 %

Physical Properties

Physical Properties Metric Imperial
Density 7.87 g/cc 0.284 lb/in3

Mechanical Properties

Mechanical Properties Metric Imperial
Hardness, Brinell 126 126
Hardness, Knoop (Converted from Brinell hardness) 145 145
Hardness, Rockwell B (Converted from Brinell hardness) 71 71
Hardness, Vickers (Converted from Brinell hardness) 131 131
Tensile Strength, Ultimate 440 MPa 63800 psi
Tensile Strength, Yield 370 MPa 53700 psi
Elongation at Break (In 50 mm) 15.0 % 15.0 %
Reduction of Area 40.0 % 40.0 %
Modulus of Elasticity (Typical for steel) 205 GPa 29700 ksi
Bulk Modulus (Typical for steel) 140 GPa 20300 ksi
Poissons Ratio (Typical For Steel) 0.290 0.290
Machinability (Based on AISI 1212 steel. as 100% machinability) 70 % 70 %
Shear Modulus (Typical for steel) 80.0 GPa 11600 ksi

Electrical Properties

Electrical Properties Metric English Comments
Electrical resistivity @0°C (32°F) 0.0000159 Ω-cm 0.0000159 Ω-cm annealed condition
@100 °C/ 212 °F 0.0000219 Ω-cm 0.0000219 Ω-cm annealed condition
@ 200 °C/392 °F 0.0000293 Ω-cm 0.0000293 Ω-cm annealed condition

Machining

The machinability of AISI 1018 mild/low carbon steel is graded at 78% of B1112.

Weldability

AISI 1018 mild/low carbon steel can be instantly welded by all the conventional welding processes.

 

 

A36:

 

Introduction

ASTM A36 is the most commonly used mild and hot-rolled steel. It has excellent welding properties and is suitable for grinding, punching, tapping, drilling and machining processes. Yield strength of ASTM A36 is less than that of cold roll C1018, thus enabling ASTM A36 to bend more readily than C1018. Normally, larger diameters in ASTM A36 are not produced since C1018 hot roll rounds are used.

ASTM A36 is usually available in the following forms:

  • Rectangle bar
  • Square bar
  • Circular rod
  • Steel shapes such as channels, angles, H-beams and I-beams.

Chemical Composition

Element Content
Carbon, C 0.25 - 0.290 %
Copper, Cu 0.20 %
Iron, Fe 98.0 %
Manganese, Mn 1.03 %
Phosphorous, P  0.040 %
Silicon, Si 0.280 %
Sulfur, S  0.050 %

Physical Properties

Physical Properties Metric Imperial
Density 7.85 g/cm3 0.284 lb/in3

Mechanical Properties

Mechanical Properties Metric Imperial
Tensile Strength, Ultimate 400 - 550 MPa 58000 - 79800 psi
Tensile Strength, Yield 250 MPa 36300 psi
Elongation at Break (in 200 mm) 20.0 % 20.0 %
Elongation at Break (in 50 mm) 23.0 % 23.0 %
Modulus of Elasticity 200 GPa 29000 ksi
Bulk Modulus (typical for steel) 140 GPa 20300 ksi
Poissons Ratio 0.260 0.260
Shear Modulus 79.3 GPa 11500 ksi

Machining

The machinability rate of ASTM A36 is estimated to be 72%, and the average surface cutting feed of ASTM A36 is 120 ft/min. Machining of ASTM A36 steel is not as easy as that of AISI 1018 steel.

Welding

ASTM A36 steel is easy to weld using any type of welding methods, and the welds and joints so formed are of excellent quality.

Heat Treatment

Any standard carburizing and hardening methods of AISI 1018 steel is suitable for ASTM A36.

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Forgive me if I am reading this wrong, but doesn't this indicate that A36 steel is NOT mystery mixed metal like some people claim? 

I am reading this that it has some slight variations in carbon content, but otherwise it is not the same as rebar in terms of its variability of content in the same bar. 

 

Is there anything I am missing? 

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More tramp elements,  You haven't compared all the physical properties and what makes them differ?

Horses have 4 legs but there is a difference between Rocinante and Secretariat even if their coat is the same colour.

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A36 is less consistent than 1018. Rebar is less consistent than A36.

Rebar has fewer mechanical requirements than A36 so the specifications are looser. The specifications for 1018 steel is an analysis specification, %s are set in stone. 

Is that more clear?

Frosty The Lucky.

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