31CrMoV9/1.8519 Alloy Steel
31CrMoV9 is a nitriding steel which has at least 2.3%Cr,0.15%Mo,0.1%V as strengthening alloy elements. Due to its high wear resistance,it is mainly used in the automotive industry and general components mechanical engineering.30CrMoV9 is difficult to weld and therefore should not be used in weld constructions.It can attain surface hardness of 800 HV after nitriding.
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 |
Mechanical Properties
| 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 |
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.
Heat Treatment
| Heat Treatment Process | Temperature Range | Holding Time | Cooling Method | Maximum Hardness |
|---|---|---|---|---|
| Soft Annealing | Heat to 650-720℃ | N/A | Cool slowly in furnace | 248 HB |
| Hardening | Harden from 870-930℃ | N/A | Oil/Polymer or Water Quenching | N/A |
| Tempering | Tempering temperature: 580-700℃ | N/A | Air Cooling | N/A |
| Nitriding | Gas/Plasma Nitriding Temperature: 570-580℃ (Gas, Salt Bath) <br> Gas/Plasma Nitriding Temperature: 580℃ (Powder, Plasma) | N/A | N/A | Surface Hardness after Nitriding: 800 HV |
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.
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