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C45

Unalloyed medium carbon steel β€” most widely used engineering steel. Q+T achieves 700-900 MPa. For shafts, gears, axles and structural parts.

Carbon Steels Medium Carbon Steel EN / ISOC45 DINCK45 / 1.1191 AISI/SAE1045 ASTMA29 Grade 1045 +12
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Description

C45 per EN 10083-2 is the reference medium-carbon unalloyed steel. Its 0.42-0.50% C content gives an excellent balance between strength (Q+T: 700-900 MPa), machinability and cost. Used worldwide for general-purpose machine elements. Surface hardening by induction or flame achieves HRC 52-58. The GOST equivalent 45 (45 steel) is one of the most produced steels in the world.

Key Properties β€” Soft Annealed
Rm (Tensile Strength)
620 – 780
MPa
Re / Rp0.2 (Yield)
340 – 510
MPa
Aβ‚… (Elongation)
β‰₯ 16.0
%
Hardness
174 – 212
HB
E (Young's Modulus)
210
GPa
Density
7.85
g/cmΒ³
Main Designations (16)
Standard BodyDesignationCountry / RegionNote
EN / ISO C45 European Union / International
DIN CK45 / 1.1191 Germany
AISI/SAE 1045 USA
ASTM A29 Grade 1045 USA
BS 080M46 (EN8) United Kingdom
JIS S45C Japan
GOST 45 (45 steel) Russia / CIS
UNI C45 Italy
NF XC45 France
SS 1672 Sweden
PN C45 Poland
CSN 12050 Czech Republic
UNS G10450 USA (UNS)
GB 45 China
JUS C.1531 Yugoslavia / Serbia Medium carbon structural/Q+T steel; JUS B.B1.100
ONORM C45 Austria
Standards (16)
#Standard BodyDesignationCountry / RegionNote
1 EN / ISO C45 European Union / International β€”
2 DIN CK45 / 1.1191 Germany β€”
3 AISI/SAE 1045 USA β€”
4 ASTM A29 Grade 1045 USA β€”
5 BS 080M46 (EN8) United Kingdom β€”
6 JIS S45C Japan β€”
7 GOST 45 (45 steel) Russia / CIS β€”
8 UNI C45 Italy β€”
9 NF XC45 France β€”
10 SS 1672 Sweden β€”
11 PN C45 Poland β€”
12 CSN 12050 Czech Republic β€”
13 UNS G10450 USA (UNS) β€”
14 GB 45 China β€”
15 JUS C.1531 Yugoslavia / Serbia Medium carbon structural/Q+T steel; JUS B.B1.100
16 ONORM C45 Austria β€”
All values in wt.%
C
Carbon
0.4200 – 0.5000
Si
Silicon
0.1700 – 0.3700
Mn
Manganese
0.5000 – 0.8000
P
Phosphorus
≀ 0.0350
S
Sulphur
≀ 0.0350
Cr
Chromium
≀ 0.4000
Ni
Nickel
≀ 0.4000
Mo
Molybdenum
≀ 0.1000
ElementSymbolMin %Max %Typical %
Carbon C 0.4200 0.5000 0.4500
Silicon Si 0.1700 0.3700 0.2500
Manganese Mn 0.5000 0.8000 0.6500
Phosphorus P β€” 0.0350 β€”
Sulphur S β€” 0.0350 β€”
Chromium Cr β€” 0.4000 β€”
Nickel Ni β€” 0.4000 β€”
Molybdenum Mo β€” 0.1000 β€”
Mechanical Properties
ConditionCode Rm min
MPa		Rm max
MPa		 Re min
MPa		Re max
MPa		 Aβ‚… min
%		 Z
%		 KV
J		 HB minHB max HRC minHRC max E
GPa
Soft Annealed +A 620 780 340 510 16.0 45.0 β€” 174 212 β€” β€” 210.0
Normalized +N 700 850 490 610 14.0 45.0 β€” 207 255 β€” β€” 210.0
Q+T 600 C (<=16mm) +QT600 700 850 490 610 16.0 50.0 47.0 207 255 β€” β€” 210.0
Q+T 550 C (<=16mm) +QT550 800 950 580 710 13.0 47.0 37.0 238 285 β€” β€” 210.0
Q+T 500 C (<=16mm) +QT500 900 1,050 650 800 11.0 40.0 30.0 269 320 β€” β€” 210.0
Induction Hardened (surface) IH β€” β€” β€” β€” β€” β€” β€” β€” β€” 52.0 58.0 210.0
Physical Properties
Density
7.850
g/cmΒ³
Melting Point
1425–1465
Β°C
Young's Modulus
210.0
GPa
Poisson's Ratio
0.300
β€”
Thermal Conductivity
50.0
W/mΒ·K
Thermal Expansion
11.00
Γ—10⁻⁢ /K
Specific Heat
490
J/kgΒ·K
Electrical Resistivity
0.1800
¡Ω·m
Magnetic
Yes
 
Heat Treatment
Soft Annealing
Temperature:650Β°C – 700Β°C
Medium:Furnace
Duration:2-4 h
Cooling:Slow furnace cool <=20 C/h
Hardness After:<=HB 207
Before heavy machining.
Normalizing
Temperature:820Β°C – 860Β°C
Medium:Still Air
Duration:-
Cooling:Air cool
Hardness After:<=HB 229
Standard delivery for bar stock.
Austenitizing (Q+T)
Temperature:820Β°C – 860Β°C
Medium:Oil
Duration:20-30 min
Cooling:Oil quench
Hardness After:HRC 45-55
Oil preferred over water. Through-hardens up to ~35 mm.
Tempering
Temperature:500Β°C – 660Β°C
Medium:Recirculating furnace
Duration:1-2 h
Cooling:Air cool
Hardness After:HRC 22-38
Select temperature for required hardness.
Induction Hardening
Temperature:820Β°C – 880Β°C
Medium:-
Duration:-
Cooling:Water/polymer spray
Hardness After:HRC 52-58 surface
Case depth 1-3 mm. Temper at 150-180 C within 2h.
Machinability
Machinability Rating
relative to AISI B1112 = 100%
65.0%
Moderate
Turning Speed (HSS)
40
m/min
Turning Speed (Carbide)
185
m/min
Feed Rate (Turning)
0.220
mm/rev
Drilling Speed (HSS)
28
m/min
Milling Speed (Carbide)
188
m/min
CoolantSoluble oil 5-8%
Chip FormationMedium chips (annealed); short-brittle (Q+T)
Tool MaterialHSS M2; carbide P20/P30; TiAlN coated
Surface FinishRa 0.8-3.2 um
Reference machinability standard. Machine in normalized or annealed condition. Machinability rating 65% vs AISI B1112=100%.
Applications
Mechanical Engineering
Shafts, axles, gear blanks, couplings, cams and gudgeon pins.
Automotive
Crankshafts (light duty), camshafts, brake drums, clutch discs and wheel hubs.
Agricultural Machinery
Drive shafts, PTO shafts, drawbar pins and tractor components.
Fasteners
Bolts and studs up to property class 8.8.
Technical Notes
πŸ”₯
Weldability
Limited. CE approx 0.65. Pre-heat to 150-250 C for sections >20 mm. Post-weld stress relief at 550-600 C recommended. Use low-hydrogen electrodes.
βœ…
Surface Hardening
Induction hardening to HRC 52-58 (case 1-3 mm) significantly extends wear life. Used for crankshaft journals, cam lobes, gear teeth and guide rails.
πŸ’§
Corrosion Resistance
No inherent corrosion resistance. Protect with paint, oil, phosphating, electroplating or hot-dip galvanizing as appropriate for environment.
Stress-Strain β€” C45 Normalized

Schematic stress-strain for C45 in normalized condition. Upper yield point visible at approx 490 MPa.

Hardness vs. Tempering Temperature β€” C45

HRC of C45 after oil quenching from 850 C and tempering 1h.