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50CrMo4

High-carbon Cr-Mo steel. Highest strength in the EN 10083 Cr-Mo series. For heavy-duty springs, highly loaded bolts and wear-resistant components.

Alloy Steels Cr-Mo Spring / Q+T Steel EN / ISO47CrMo4 / 1.7228 (nearest) DIN47CrMo4 / 1.7228 AISI/SAE4147 (nearest) BS EN709M47 (nearest) +13
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Description

50CrMo4 per EN 10083-3 (EN 1.7228). Higher C than 42CrMo4 gives greater hardness after quenching (HRC 56-60) and higher fatigue strength. Tempered at 350-450 C achieves Rm 1300-1500 MPa. Used for heavy-duty torsion bars, heavily loaded structural bolts, rock drill rods and heavy spring applications.

Key Properties — Normalized
Rm (Tensile Strength)
780 – 980
MPa
Re / Rp0.2 (Yield)
580
MPa
A₅ (Elongation)
≥ 13.0
%
Hardness
225 – 285
HB
E (Young's Modulus)
210
GPa
Density
7.85
g/cm³
Main Designations (17)
Standard BodyDesignationCountry / RegionNote
EN / ISO 47CrMo4 / 1.7228 (nearest) EU
DIN 47CrMo4 / 1.7228 Germany
AISI/SAE 4147 (nearest) USA
BS EN 709M47 (nearest) UK
JIS SCM447 (nearest) Japan
GOST 47HM (47KhM) Russia
UNS G41470 (nearest) USA (UNS)
GB 47CrMo4 China
JUS C.4453 Yugoslavia Cr-Mo alloy Q+T; JUS C.B1.042
EN 10083-3 50CrMo4 / 1.7228 EU
DIN W.Nr 1.7228 Germany
AISI/SAE 4150 (nearest) USA
ASTM A322 Grade 4150 (nearest) USA
JIS SCM445 (nearest) Japan
GOST 50HM nearest Russia
UNS G41500 USA (UNS)
JUS C.4734 Yugoslavia/BiH Cr-Mo Q+T celik visi C; JUS C.B1.042
Standards (17)
#Standard BodyDesignationCountry / RegionNote
1 EN / ISO 47CrMo4 / 1.7228 (nearest) EU —
2 DIN 47CrMo4 / 1.7228 Germany —
3 AISI/SAE 4147 (nearest) USA —
4 BS EN 709M47 (nearest) UK —
5 JIS SCM447 (nearest) Japan —
6 GOST 47HM (47KhM) Russia —
7 UNS G41470 (nearest) USA (UNS) —
8 GB 47CrMo4 China —
9 JUS C.4453 Yugoslavia Cr-Mo alloy Q+T; JUS C.B1.042
10 EN 10083-3 50CrMo4 / 1.7228 EU —
11 DIN W.Nr 1.7228 Germany —
12 AISI/SAE 4150 (nearest) USA —
13 ASTM A322 Grade 4150 (nearest) USA —
14 JIS SCM445 (nearest) Japan —
15 GOST 50HM nearest Russia —
16 UNS G41500 USA (UNS) —
17 JUS C.4734 Yugoslavia/BiH Cr-Mo Q+T celik visi C; JUS C.B1.042
All values in wt.%
C
Carbon
0.4600 – 0.5400
Si
Silicon
0.1500 – 0.4000
Mn
Manganese
0.5000 – 0.8000
Cr
Chromium
0.9000 – 1.2000
Mo
Molybdenum
0.1500 – 0.3000
ElementSymbolMin %Max %Typical %
Carbon C 0.4600 0.5400 0.5000
Silicon Si 0.1500 0.4000 0.2500
Manganese Mn 0.5000 0.8000 0.6500
Chromium Cr 0.9000 1.2000 1.0500
Molybdenum Mo 0.1500 0.3000 0.2200
Mechanical Properties
ConditionCode Rm min
MPa		Rm max
MPa		 Re min
MPa		Re max
MPa		 A₅ min
%		 Z
%		 KV
J		 HB minHB max HRC minHRC max E
GPa
Normalized +N 780 980 580 — 13.0 42.0 — 225 285 — — 210.0
Q+T 650C +QT650 1,000 1,200 800 — 11.0 40.0 40.0 295 355 — — 210.0
Q+T 550C +QT550 1,100 1,300 900 — 9.0 35.0 32.0 320 380 — — 210.0
Physical Properties
Density
7.850
g/cm³
Melting Point
1410–1450
°C
Young's Modulus
210.0
GPa
Poisson's Ratio
0.290
—
Thermal Conductivity
40.0
W/m·K
Thermal Expansion
12.30
×10⁻⁶ /K
Specific Heat
480
J/kg·K
Electrical Resistivity
0.2300
µΩ·m
Magnetic
Yes
 
Heat Treatment
Soft Annealing
Temperature:680°C – 720°C
Medium:Furnace
Duration:4-6 h
Cooling:<=20 C/h
Hardness After:<=HB 248
Before machining.
Austenitizing
Temperature:820°C – 860°C
Medium:Oil quench
Duration:20-30 min
Cooling:Oil quench
Hardness After:HRC 53-60
Hardenability to 40-50 mm.
Tempering
Temperature:450°C – 650°C
Medium:Oven
Duration:1.5-2 h
Cooling:Air cool
Hardness After:HRC 30-48
Select per application.
Machinability
Machinability Rating
relative to AISI B1112 = 100%
52.0%
Difficult
Turning Speed (HSS)
30
m/min
Turning Speed (Carbide)
138
m/min
Feed Rate (Turning)
0.160
mm/rev
Drilling Speed (HSS)
21
m/min
Milling Speed (Carbide)
140
m/min
CoolantSoluble oil 5-8%
Chip FormationMedium-short chips
Tool MaterialCarbide P20 TiAlN
Surface FinishRa 0.8-1.6 um
Slightly more difficult than 42CrMo4 due to higher C -- similar machining approach.
Applications
Shafts
Heavily loaded drive shafts, axles and power transmission shafts.
Gears
Heavy-duty gears where Q+T properties are used (not case-hardened).
Fasteners
12.9 class bolts and studs for large section sizes.
Heavy Shafts
Large machine shafts and spindles requiring strength above 42CrMo4 capability.
Gears
High-load through-hardened gears in industrial gearboxes.
High-Strength Bolts
Large diameter structural bolts where 42CrMo4 hardenability is marginal.
Technical Notes
✅
vs 42CrMo4
47CrMo4 gives ~10% higher Rm at equivalent tempering temperature. Use when 42CrMo4 at Q+T provides insufficient safety margin and 50CrMo4 would be excessive.
✅
50CrMo4 vs 42CrMo4 vs 34CrNiMo6
42CrMo4: Rm 900-1100 MPa, the default. 50CrMo4: Rm 1000-1200 MPa, higher C, same Cr-Mo cost. 34CrNiMo6: Rm 1100-1300 MPa, Ni addition, best toughness. Step up from 42CrMo4 to 50CrMo4 first if Ni alloy cost should be avoided.