SCM 440 / AISI 4140 / VCL 140
AISI 4140 is a chromium-molybdenum alloy steel. The chromium content provides good hardness penetration, and the molybdenum content ensures uniform hardness and high strength. AISI 4140 chrome-molybdenum steel can be oil hardened to a relatively high level of hardness. The desirable properties of the AISI 4140 include superior toughness, good ductility and good wear resistance in the quenched and tempered condition.
The AISI 4140 cold finished annealed chromium-molybdenum alloy steel can be heated using various methods to yield a wide range of properties, hence it is often used as stock for forging as it has self-scaling properties. AISI 4140 is capable of resisting creep in temperatures up to 538°C (1000°F) and maintaining its properties even after long exposure at comparatively high working temperatures. The AISI 4140 cold rolled rounds are available in the 41L40 variant that contains 0.15-0.35 lead. The lead content improves machinability, but has significant effect on other desirable properties.

Composition(%)
C 0.38-0.43
Si 0.15-0.35
Mn 0.60-0.85
P/S 0.030 max
Cr 0.90-1.20
Mo 0.15-0.30
Heat Treatment(°C)
Normalizing 830-880 (Air cooling)
Annealing 830 (Furnace cooling)
Hardening 830-880 (Oil quenching)
Tempering 530-630 (Rapid cooling
Hardness
Annealed 255 HB MAX
Tempered 30-38 HRC
Size Availability
Round Bar:
13mm-355mm
Equivalent
AISI 4140, SCM440, VCL140, Thyssen 7225, DIN 42CrMo4, ASSAB 709, BOHLER V320, ST70

SNCM 439 / AISI 4340 / VCN 150
AISI 4340 alloy steel is a heat treatable and low alloy steel containing chromium, nickel and molybdenum. It has high toughness and strength in the heat treated condition.
Composition(%)
C 0.36-0.43
Si 0.15-0.35
Mn 0.60-0.90
P/S 1.60-2.00
Cr 0.60-1.00
Mo 0.15-0.30
Heat Treatment(°C)
Normalizing 820-870 (Air cooling)
Annealing 820 (Furnace cooling)
Hardening 820-870 (Oil quenching)
Tempering 580-680 (Rapid cooling
Hardness
Annealed 255 HB MAX
Tempered 31-38 HRC
Size Availability
Round Bar:
25mm-350mm
Equivalent
ST90, AISI 4340, VCN 150, SNCM439, ASAB 705, Thyssen 6582, DIN 34NiCrMo6, ASSAB 705, Atlas Ultimo 200
SCM 415 / AISI 4115
Low carbon and Cr-Mo heat treated by surface hardening process, use for gears and wear resistant parts with tough cores.

Composition(%)
C 0.13-0.18
Si 0.15-0.35
Mn 0.60-0.85
P/S 0.030 Max
Cr 0.90-1.20
Mo 0.15-0.30
Heat Treatment(°C)
Normalizing 850-900 (Air cooling)
Annealing 850 (Furnace cooling)
Hardening 1st 850-900 (Oil quenching)
2nd 800-850 (Oil quenching)
Tempering 150-200 (Rapid cooling)
Hardness
Annealed 255 HB MAX
Tempered 31-38 HRC
Size Availability
Round Bar:
25mm – 210mm. *Fix 6 Meters Length
Equivalent
SCM 415, AISI 4115, DIN 1.7218, DIN 15CrMo5