Materials: Carbon Steel

Features and applications of common carbon steel alloys

Low carbon steels generally contain less than 0.25% carbon and cannot be strengthened by heat-treating (strengthening can only be accomplished through cold working). The low carbon material is relatively soft and weak, but has outstanding ductility and toughness. In addition, it is machineable, weld-able, and is relatively inexpensive to produce.

Medium carbon steels have carbon concentrations between 0.25% and 0.60%. These steels may be heat-treated by austenizing, quenching, and then tempering to improve their mechanical properties. On a strength-to-cost basis, the heat-treated medium carbon steels provide tremendous load carrying ability.

An iron-based mixture is considered to be an alloy steel when manganese is greater than 1.65%, silicon over 0.5%, copper above 0.6%, or other minimum quantities of alloying elements such as chromium, nickel, molybdenum, vanadium, or tungsten are present. An enormous variety of distinct properties can be created for the steel by substituting these elements in the recipe to increase hardness, strength, or chemical resistance.

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Low Carbon Steels – Principal Design Features & Applications

Alloy

UNS Designation

Principal Design Features

Applications

1010

G10100

1010 is a plain carbon steel with a nominal 0.10% carbon content. It is a relatively low strength steel, but it may be quenched and tempered for increased strength.

Used for applications such as cold headed fasteners and bolts.

1018

G10180

1018 is among the most available grades in the world. Despite its unimpressive mechanical properties, the alloy is easily formed, machined, welded, and fabricated. Due to its higher manganese content, it can, in thin sections, be hardened to RC 42.

Often employed in high volume screw machine parts applications, such as shafts, spindles, pins, rods, sprocket assemblies, and an incredibly wide variety of component parts.

1020

G10200

1020 is a commonly used plain carbon steel. It has a nominal carbon content of 0.20% with approximately 0.50% manganese. It has a good combination of strength and ductility and may be hardened and carburized.

Used for simple structural applications such as cold formed fasteners and bolts. It is often used in the case hardened condition.

1022

G10220

1022 has a slightly higher carbon and manganese content plain carbon steel than 1020. It is used for its somewhat greater strength while still having good ductility.

Used for moderate strength structural applications such as cold formed fasteners and bolts. It is often used in the case hardened condition.

Medium Carbon Steels – Principal Design Features & Applications

Alloy

UNS Designation

Principal Design Features

Applications

1030

G10300

1030 is a higher carbon (0.30%) manganese steel in the plain carbon steel alloy family. It provides greater strength than the lower grades while still retaining reasonable ductility.

Generally used in the quenched and tempered condition for strength. Applications include machinery parts where strength and hardness are requisite.

1040

G10400

1040 has a higher (0.40%) carbon content for greater strength than the lower carbon alloys. It is hardenable by heat treatment, quench and tempering to develop 150 to 250 ksi tensile strength.

Used for crankshafts, couplings, and cold headed parts.

1045

G10450

1045 is a medium carbon steel used when greater strength and hardness is desired than in the rolled condition.

Used in gears, shafts, axles, bolts, studs, and machine parts.

1060

G10600

1060 is one of the higher carbon content (0.60%) steels. It is more difficult to fabricate than the lower carbon grades.

Used for hand tools such as screwdrivers, pliers, and similar items.

Alloy Steel – Principal Design Features & Applications

Alloy

UNS Designation

Principal Design Features

Applications

4130

G41300

4130 is a low alloy steel containing molybdenum and chromium as strengthening agents. The carbon content is nominally 0.30%, and with this relatively low carbon content, the alloy is excellent from the fusion weldability standpoint. The alloy can be hardened by heat treatment.

Used in structural applications such as aircraft engine mounts and welded tubing applications.

4140

G41400

4140 is one of the chromium, molybdenum, manganese alloy steels noted for toughness, good torsional strength, and good fatigue strength.

Used in a tremendous variety of applications.

4330

G43300

4330 is a heat treatable steel alloy containing chromium, nickel, and molybdenum. Carbon content is in the 0.30% range and, in the heat treated condition, the alloy has good toughness and fatigue strength as well as overall strength.

Used in applications that require a good combination of strength and impact resistance, such as gears, aircraft landing gear axles, and shafts for power transmissions.

4340

G43400

4340 is a heat treatable, low alloy steel containing nickel, chromium, and molybdenum. It is known for its toughness and capability of developing high strength in the heat treated condition, while retaining good fatigue strength.

Typically used for aircraft landing gear, power transmission gears and shafts, and other structural parts.

Low Carbon Steels – Chemical Properties

Alloy UNS
Designation
C
(max)
Mn
(max)
P
(max)
S
(max)
Si Cr Ni Mo Other
Elements
1010 G10100 0.08-0.13% 0.30-0.60% 0.04% 0.05% - - - - -
1018 G10180 0.14-0.20% 0.60-0.90% 0.04% 0.05% - - - - -
1020 G10200 0.17-0.23% 0.30-0.60% 0.04% 0.05% - - - - -
1022 G10220 0.17-0.23% 0.70-1.00% 0.04% 0.05% - - - - -

Medium Carbon Steel Chemical Properties

Alloy UNS
Designation
C
(max)
Mn
(max)
P
(max)
S
(max)
Si Cr Ni Mo Other
Elements
1010 G10100 0.08-0.13% 0.30-0.60% 0.04% 0.05% - - - - -
1018 G10180 0.14-0.20% 0.60-0.90% 0.04% 0.05% - - - - -
1020 G10200 0.17-0.23% 0.30-0.60% 0.04% 0.05% - - - - -
1022 G10220 0.17-0.23% 0.70-1.00% 0.04% 0.05% - - - - -

Alloy Steel Chemical Properties

Alloy UNS
Designation
C
(max)
Mn
(max)
P
(max)
S
(max)
Si Cr Ni Cu Other
Elements
405 S40500 0.08% 1% 0.04% 0.03% 1% 11.5-14.5% 1-3%
Aluminum
430 S43000 0.12% 1% 0.04% 0.03% 1% 16-18%

 

Low Carbon Steels – Mechanical Properties

Low carbon steels are relatively soft and weak, but have outstanding ductility and toughness. In addition, they are machinable, weldable, and are relatively inexpensive to produce.

Alloy UNS
Designation
Typical Mechanical Properties
Tensile
(ksi)
Yield
(ksi)
Elongation
(% in 2″)
Reduction of
Area (%)
Brinell
Hardness
1010 G10100 53 44 20 40 105
1018 G10180 64 54 15 40 126
1020 G10200 64 54 24 54 126
1022 G10220 69 58 15 40 137

Medium Carbon Steels – Mechanical Properties

Medium carbon steels may be heat-treated by austenizing, quenching, and then tempering to improve their mechanical properties. On a strength-to-cost basis, the heat-treated medium carbon steels provide tremendous load carrying ability.

Alloy UNS
Designation
Typical Mechanical Properties
Tensile
(ksi)
Yield
(ksi)
Elongation
(% in 2″)
Reduction of
Area (%)
Brinell
Hardness
1030 G10300 76 64 12 35 149
1040 G10400 90 80 12 35 170
1045 G10450 91 77 12 35 179
1060 G10600 118 70 17 34 241

Alloy Steels – Mechanical Properties

An enormous variety of distinct properties can be created for alloy steel by substituting the chemical elements in the recipe to increase hardness, strength, or chemical resistance.

Alloy UNS
Designation
Typical Mechanical Properties
Tensile
(ksi)
Yield
(ksi)
Elongation
(% in 2″)
Reduction of
Area (%)
Brinell
Hardness
4130 G41300 80 56 28 57 149
4140 G41400 150 90 20 45 285
4330 G43300 125 100 15 30 250-325
4340 G43400 110 66 23 49 197