24 July 2021 Gear Steel Bar
17CrNiMo6 Gear Steel Bar
17CrNiMo6 is a Chrome-Nickel-Moly Carburising Steel generally supplied annealed to HB 229max. Carburised and heat treated it develops a hard wear resistant case to HRC 60-63 and a tough strong core with a typical tensile strength range of 900-1300 MPa, in small to fairly large sections. The new standard rename grade into 18CrNiMo7-6 .
17CrNiMo6 alloy steel is is a heat treatable, low alloy steel containing nickel, chromium and molybdenum as per DIN Germany standard which is known for its toughness and capability of developing high strength in the heat treated condition while retaining good fatigue strength. 17CrNiMo6 alloy steel is widely used in heavy duty shafts, gears, axles, spindles, souplings, pins etc.
Chemical Composition:
Carbon | 0.18% |
Silicon | 0.20% |
Manganese | 0.70% |
Chromium | 1.65% |
Nickel | 1.55% |
Molybdenum | 0.30% |
Mechanical Properties(Quenched and Tempered at 200°C):
Section mm | Yield Strength MPa | Tensile Strength MPa | Elongation % | Impact Izod J | Hardness HB |
25 | 1050 | 1295 | 14 | 45 | 380 |
50 | 950 | 1160 | 15 | 51 | 340 |
100 | 815 | 1010 | 16 | 53 | 300 |
Hardenability limits:
Distance from quenched end – mm | |||||||||||||
Hardness values max - min – HRC | |||||||||||||
mm | 1.5 | 3 | 5 | 7 | 9 | 11 | 13 | 15 | 20 | 25 | 30 | 35 | 40 |
HRC | 48 | 48 | 48 | 48 | 47 | 47 | 46 | 46 | 44 | 43 | 42 | 41 | 41 |
HRC | 40 | 40 | 39 | 38 | 37 | 36 | 35 | 34 | 32 | 31 | 30 | 29 | 29 |
WELDING:
Readily welded in the annealed condition with the correct procedure, but welding in the case hardened or through hardened condition is not recommended.
HEAT TREATMENT:
Forging:
Heat to 1150°C Hold till uniform
Minimum forging temperature 850°C Cool slowly in ashes or sand etc
Annealing:
Heat to 830°C – 850°C
Cool in furnace
Stress Relieving:
Heat to 630°C – 650°C
Cool in still air
Hardening:
Heat to 820°C – 850°C
Cool in Air or Oil required
Tempering:
Heat to 150°C – 200°C
Cool in still air
Welding procedure:
The use of low hydrogen electrodes recommended. Pre-heat at 250°C – 350°C and maintain during welding. Cool slowly in ashes etc, followed if possible with a stress-relieve.
Welding details for guidance only
Carburising:
Carburise at 900°C – 950°C
Core Refining (Optional):
Heat to 830°C – 870°C
Cool in air, oil or salt bath held at 150°C – 200°C
– then air cool
Case Hardening:
Heat to 780°C – 820°C
Quench in water
Tempering:
Temper at 150°C – 200°C to improve case toughness with minimal effect on its hardness. This will also reduce the possibility of grinding cracks.
Nitriding:
Heat to 500°C – 530°C
Heat treatment details for guidance only