M-2B is a modified version of M-2, used for cutting tools, for example, drilling bits, screw taps, milling cutters, drawing tools, roller cutters, etc.
Smelting method : 15T Intermediate frequency furnace +LF+VD+ESR
Major Characteristics : Favorable tenacity, high red hardness and excellent abrasion resistance.
Major Applications : Due to favorable hardness and abrasion resistance, it's mainly used to fabricate tools to cut materials which are difficult to be cut. It;s mainly used as various cutting tools, for example, drilling bits, screw taps, milling cutters, drawing tools, roller cutters, etc.
Chemical Constituent (%) :
| C | W | Mo | Cr | Cr |
| 0.89 | 6.2 | 4.8 | 4.15 | 3.95 |
| V | Co | P | S |
| 1.9 | - | ≤0.026 | ≤0.003 |
| O (ppm) | N (ppm) | H (ppm) |
| ≤20 | ≤100 | ≤2.5 |
Physical Property :
| Room temperature density (g/cm³) | Specific heat of room temperature (J/g.K) | 20°C thermal conductivity (W/m.K) |
| 8.12 | 0.46 | 19.0 |
| Elastic mouldsus (N/nm²) | Resistivity (Ohm mm²/m)
|
| 217,000 | 0.54 |
Ultrasonic flaw detection :
As per SEP1921 D/d or customer requirements.
Purity :
| Class A | Class B | ||
| Fine | Coarse | Fine | Coarse |
| 0.5 | 0.5 | 0.5 | 0.5 |
| Class C | Class D | ||
| Fine | Coarse | Fine | Coarse |
| 0.5 | 0.5 | 1.0 | 0.5 |
Delivery State :
(1) Delivery under balling annealing state, delivery hardness ≤269HB.
Production Process :
Sizes of Round Bars :
| Cold Drawn/Ground Bar | Hot Rolled Annealed & Peeled Bar |
| Φ 2.0 - 14.4mm | Φ 14.5 - 80.0mm |
| Forged + Annealed + Turned Bar | Coil |
| Φ 81.0 - 255.0mm | Φ 2.0 - 13.5mm |
Thermal Treatment :
| Softening annealing | Quenching |
| Heating to 860-880°C for heat insulation; cooling to 550°C slowly and then removing from the furnace. | 1,210~1,220°C quenching, slat bath; Air cooling to room temperature after 500~600°C level by level quenching |
| Tempering |
| Tempering temperature 540~560°C; tempering for 3 times; material temperature shall reach the temperature interval; each time of heat insulation shall be not less than 1hr; air cooling to room temperature |
