C15 is a plain carbon steel with a nominal 0.15% carbon content. It is a relatively low strength steel but it may be quenched and tempered for increased strength.

Chemical composition

Element Min Max
Carbon, C -.– 0.20
Manganese, Mn -.– 0.80
Silicon, Si -.– 0.10
Sulfur, S -.– 0.06
Phosphorous, P -.– 0.06

Mechanical Properties

Nominal thickness (mm): 5-10 10-16 16 - 40 40 - 63 63 - 100
Rm - Tensile strength (MPa) (+C) 500-800 480-780 430-730 380-670 340-600
Nominal thickness(mm): 5-10 10-16 16 - 40 40 - 63 63 - 100
R p0.2 0.2% proof strength (MPa) (+C) 380 340 280 240 215
Nominal thickness (mm): 5-10 10-16 16 - 40 40 - 63 63 - 100
A - Min. elongation at fracture (%) (+C) 7 8 9 11 12
Element C Mn Si S P cr Ni Mo
Min .90 .35 .10 0.00 0.00 1.00 -
Max 1-20 .75 .35 .35 .35 1.60 - -

Coefficient of Linear Thermal Expansion 10^-6 °C^-1

20-100°C 20-100°C
11 11.8

Physical Properties(avarage values) at ambient temperature

Properties Metric
Modulus of elasticity [10^3x N/mm2] 210
Density [g/cm3]: 7.85
Thermal conductivity [W/m.11] 58.6
Electric resistivity [Ohm mm2/m]: 0.11
Specific heat capacity[lig.11] 0.46

The low carbon steels, such as C15 are used for applications such as cold headed fasteners and bolts.

Soft Annealing

Heat to 850-950°C, cool slowly. This will produce a hardness of 90-100 HB.

Stress Relieving

Stress relieving to remove machining stresses should be carried out by heating to approx. 540°C, holding for 1-2 hours at heat, followed by air cooling. This operation is performed to reduce distortion during heat treatment.


Hot forming temperature: 1200-950°C.


Machinability of C15 steel is fairly good, especially in the cold drawn or cold worked condition. Based upon carbon steel AIS11112 as a reference that is considered 100% machinable (easily machined) the C15 steel has a rating of 55%.

Corrosion Resistance

This is a plain carbon steel and has no corrosion resistance. It will rust unless protected.


C 15 steel may be welded by all of the standard welding techniques.
It is a soft carbon-steel, easily cold machinable and weldable without any particular precautions.

Cold Working

C 15 is easily cold worked by traditional means. Following severe cold working a stress relief, or full, anneal should be performed.

Heat treatment conditions

+A Soft annealed
+AC Annealed to achieve spheroidization of the carbides
+AR As rolled
+AT Solution annealed
+C Cold drawn / hard
+CR Cold rolled
+FP Treated to ferrite-pearlite structure and hardness range
+I Isothermal annealing
+LC Cold drawn / soft
+M Thermo mechanical rolling
+N Normalized
+NT Normalized and tempered
+P Precipitation hardened
+PE Peeled
+QA Air quenched and tempered
+QL Liquid quenched and tempered
+QT Quenched and tempered
+S Treated to improve shearability
+SH As rolled and turned
+SR Cold drawn and stress relieved
+T Tempered
+TH Treated to hardness range
+WW Warm worked
+U Untreated
Heat Treatment

Heat treatment temperatures, including rate of heating, cooling and soaking times will vary due to factors such as the shape and size of each steel component. Other considerations during the heat treatment process include the type of furnace, quenching medium and work piece transfer facilities. Please consult your heat treatment provider for full guidance on heat treatment of alloy steel.