1.Supply Form & Size & Tolerance
Hot rolled bar:Φ6-Φ130mm,Length:3000-10000mm
Hot Forged round bar:Φ130-Φ1000mm,Length:3000-10000mm
Flat bar/Blcoks:Thickness :120-800mm xWidth:120-1500mm,Length:2000-6000mm
| Surface Finish | Tolerance |
| Black For Forged condition | (0,+5mm) |
| Black For Rolled condition | (0,+1mm) |
| Rough Turned | (0,+3mm) |
| Grinding | Best h9 |
| Polished | Best h11 |
| Peeled | Best H11 |
| Cold Drawn | Best H11 |
2.Chemical Composition
| Grade | C | Mn | P | S | Si | V | Cr | Mo |
| 31CrMoV9/1.8519 | 0.27-0.34 | 0.40-0.70 | ≤ 0.025 | ≤ 0.035 | ≤ 0.4 | 0.1-0.2 | 2.3-2.7 | 0.15-0.25 |
3.Physical Property
Density ,g/cm3: 7.85
Specific heat capacity, J/(kg.K):460
Thermal conductivity ,W/(m.K):42
Electric resistivity,Ohm.mm2 /m:0.19
Modulus of elasticity ,Gpa: 210
4. Mechanical Property
| Diameter d mm | 16-40 | 40-100 | 100-160 | 160-250 |
| Yield Strength Mpa | ≥900 | ≥800 | ≥700 | ≥650 |
| Tensile Strength Mpa | 1100-1300 | 1000-1200 | 900-1100 | 850-1050 |
| Elongation, % | ≥9 | ≥10 | ≥11 | ≥12 |
| impact,J | ≥25 | ≥30 | ≥35 | ≥40 |
| Hardness,HB | 331-380 | 298-359 | 271-331 | 253-319 |
5.Forging
Heat the temperature between 1050℃-1150℃,hold suitable time for the steel to be thoroughly heated.Reheat the steel once temperature below 850°C. Crack is easily occured when improper cooling way after forged,so it should be cooled as slowly as possible in the furnace or in sand after forged.
6.Heat Treatment
- Soft Annealing
Heat to 650-720℃, cool slowly in the furnace. This will produce a maximum Brinell hardness of 248. - Hardening
Harden from a temperature of 870-930℃, followed by oil/polymer or water quenching. - Tempering
Tempering temperature: 580-700℃. - Nitriding
Gas/plasma nitriding temperature (gas, salt bath): 570-580℃
Gas/plasma nitriding temperature (powder, plasma): 580℃
Surface hardness after nitriding: 800 HV
| Hold time,h | Hardness,HV |
| 30 | 750 | 540 | 430 | 410 | 400 | 380 | 380 |
| 90 | 830 | 750 | 640 | 530 | 430 | 410 | 410 |
| 120 | 790 | 730 | 660 | 600 | 540 | 460 | 400 |
| 180 | 800 | 760 | 700 | 640 | 580 | 550 | 420 |
| Depth,mm | 0.15 | 0.25 | 0.35 | 0.45 | 0.55 | 0.65 | 1 |
7.Jominy Test -Distance from quenched end mm
| mm | 2 | 8 | 12 | 16 | 20 | 30 | 40 | 50 | 60 | 70 |
| HRC | 51 | 50 | 50 | 49 | 48 | 46 | 44 | 42 | 41 | 41 |
8.Application
31CrMoV9 nitriding steel is used in mechanics automotive and general mechanics, which must be nitrided for very high wear forces, for example, gears, rods or axes.Structural parts of medium and large cross sections and high surface hardness, e.g., valve and gate valves, cylinders for combustion engines, superheated steam valves and fittings.
