Silicon spring steel with good toughness. For general spring applications and flat springs not requiring elevated temperature resistance.
Standards
| Standard Body |
Designation |
Country |
| EN / ISO |
38Si7 |
European Union |
| DIN |
38Si7 / 1.5023 |
Germany |
| AISI/SAE |
9255 (nearest) |
USA |
| BS EN |
251H60 (nearest) |
UK |
| JIS |
SUP6 (nearest) |
Japan |
| GOST |
55S2 (55S2) |
Russia / CIS |
| UNI |
38Si7 |
Italy |
| NF |
38S7 |
France |
| SS |
2085 (nearest) |
Sweden |
| PN |
55S2 |
Poland |
| CSN |
13255 (nearest) |
Czech Republic |
| UNS |
G92550 (nearest) |
USA |
| GB |
60Si2Mn |
China |
| JUS |
C.5223 |
Yugoslavia / Serbia |
| ONORM |
38Si7 |
Austria |
Composition (wt.%)
| Element |
Symbol |
Min % |
Max % |
Typical % |
| Carbon |
C |
0.350 |
0.420 |
0.380 |
| Silicon |
Si |
1.500 |
1.800 |
1.650 |
| Manganese |
Mn |
0.600 |
0.900 |
0.750 |
Physical
Melting Range
1400 – 1450
°C
Thermal Conductivity
38
W/mK
Thermal Expansion
12
×10⁻⁶/K
Machinability
| Rating |
50.0% (B1112=100%) |
| Turning HSS |
30.0 m/min |
| Turning Carbide |
145.0 m/min |
| Surface Finish |
Ra 0.8-1.6 um |
| Coolant |
Soluble oil 8-12% |
Mechanical
| Condition |
Rm (MPa) | Re (MPa) | A (%) |
HB | HRC | KV (J) | E (GPa) |
| Soft Annealed (+A) |
750 – 950 |
550 – 750 |
13 – 18 |
223 – 280 |
— |
— |
210 |
| Q+T (spring) (+QT) |
1300 – 1550 |
≥1150 |
≥8 |
390 – 460 |
— |
— |
210 |
Heat Treatment
| Process |
Temperature |
Medium |
Duration |
Hardness After |
| Spheroidising Anneal |
680 – 720°C |
Furnace |
3-5 h |
<=HB 255 |
| Austenitizing |
860 – 900°C |
Oil |
15-20 min |
HRC 52-58 |
| Tempering (spring) |
400 – 480°C |
Oil bath or air |
45-90 min |
HRC 42-48 |
Applications
Flat Springs: Leaf springs for railway stock, trucks and agricultural machinery.
Mining: Heavy-duty mining equipment springs and shock absorber components.
Agricultural: Plough spring assemblies and cultivator spring tines.
Notes
vs 60SiCr7: 38Si7 has better toughness (A>=8-10%) vs 60SiCr7 (A>=5-6%) — use where resistance to impact or vibration loading is important alongside spring function.