Ordinary high-speed steel is divided into tungsten-based high-speed steel and tungsten-molybdenum-based high-speed steel.
1. Tungsten-based high-speed steel (W18 for short) contains less vanadium and has good sharpening processability. The tendency of overheating during fire is small, and heat treatment control is easier. The steel grinding performance and comprehensive performance are good, and the versatility is strong. However, the distribution of carbides is often uneven, the strength and toughness are not strong enough, and the thermoplasticity is poor, so it is not suitable to be made into large-section tools. The sample diagram of tungsten high-speed steel is shown in Figure A, and its chemical composition and characteristics are shown in Table B.
| Table B: Chemical composition and characteristics of tungsten series high-speed steel | ||||||||||||
| Classification | Code | Chemical composition | Chemical composition (mass fraction, %) | Characteristic | Use | |||||||
| C | W | Mo | Cr | V | Co | Wear resistance | High temperature hardness | Toughness | ||||
| Tungsten series | SKH2 | 18-4-1 | 0.78 | 18.00 | / | 4.15 | 1.00 | / | * | ** | ** | For general cutting |
| SKH3 | 19-4-1-5 | 0.78 | 18.00 | / | 4.15 | 1.00 | 5.00 | * | *** | * | For high speed heavy cutting | |
| SKH4 | 18-4-1-10 | 0.78 | 18.00 | / | 4.15 | 1.25 | 10.00 | ** | ******* | * | Processing of difficult-to-cut materials | |
| SKHS | 20-4-1-16 | 0.3 | 19.50 | / | 4.15 | 1.25 | 16.50 | ** | ********* | * | / | |
| SKH10 | 13-4-5-5 | 1.53 | 12.50 | / | 4.15 | 4.70 | 4.70 | **** | **** | ** | For processing difficult cutting materials | |
| Note: * indicates the strength of the feature. The more * numbers, the stronger the performance. | ||||||||||||
2. Tungsten-molybdenum high-speed steel. This type of steel is made by replacing part of the tungsten with molybdenum to reduce the uneven quantity and distribution of carbides. The addition of molybdenum can improve the sharpening process and is beneficial to improving thermoplasticity and bending resistance. Strength and toughness. However, its fire temperature range is narrow and its decarburization overheating sensitivity is high. Therefore, its high temperature cutting performance is slightly worse than W18. The chemical composition and characteristics of tungsten-molybdenum high-speed steel are shown in TableC.
| Table C: Chemical composition and properties of tungsten-molybdenum high-speed steel | ||||||||||||
| Classification | Code name | Chemical composition | Chemical composition (mass fraction, %) | Characteristic | Use | |||||||
| C | W | Mo | Cr | V | Co | Wear resistance | High temperature hardness | Toughness | ||||
| Tungsten and molybdenum | SKH51 | 6-5-4-2 | 0.85 | 6.10 | 5.00 | 4.15 | 1.90 | / | ** | * | *** | For general cutting |
| SKH52 | 6-5-4-2 | 1.05 | 6.10 | 5.50 | 4.15 | 2.55 | / | *** | ** | **** | For cutting high hardness materials that require a certain degree of toughness | |
| SKH53 | 6-5-4-3 | 1.18 | 6.20 | 4.95 | 4.15 | 3.05 | / | *** | ** | *** | ||
| SKH54 | 6-5-4-4 | 1.33 | 5.90 | 5.00 | 4.15 | 4.20 | / | **** | ** | *** | ||
| SKH55 | 6-5-4-2- | 0.90 | 6.20 | 4.95 | 4.15 | 1.95 | 5.00 | *** | *** | *** | For high-speed heavy material cutting that requires a certain degree of toughness | |
| SKH56 | 6-5-4-2- | 0.90 | 6.20 | 4.95 | 4.15 | 1.95 | 8.00 | *** | **** | *** | ||
| SKH57 | 10-4-43-10 | 1.28 | 10.00 | 3.50 | 4.15 | 3.35 | 10.00 | **** | ***** | ** | ||
| SKH58 | 2-9-4-2 | 1.00 | 1.80 | 8.70 | 4.15 | 1.95 | / | *** | * | ** | For general cutting | |
| SKH59 | 1.5-10-4-1-8 | 1.08 | 1.55 | 9.50 | 4.15 | 1.15 | 8.00 | *** | *** | ** | For high speed heavy cutting | |
| Note: * indicates the strength of the feature. The more * numbers, the stronger the performance. | ||||||||||||
