Round High Speed Steel Cutting Tools Silver Powder Metallurgy Gear Hob

 Powder Metallurgy Hob

Differences between cemented carbide steel and high-speed steel:

First, the performance of the two is different
1. Performance of cemented carbide steel: The cutting speed of cemented carbide tools is 4 to 7 times higher than that of high-speed steel, and the tool life is 5 to 80 times longer. Manufacturing molds and measuring tools, the service life is 20 to 150 times higher than that of alloy tool steel. It can cut hard materials of about 50HRC.
However, cemented carbide is brittle and cannot be machined, and it is difficult to make integral tools with complex shapes. Therefore, blades of different shapes are often made, which are installed on the tool body or mold body by welding, bonding, mechanical clamping, etc. .
2. Performance of high-speed steel: tool steel with high hardness, high wear resistance and high heat resistance, also known as high-speed tool steel or front steel, commonly known as white steel. The quenching temperature of high-speed steel is generally close to the melting point of the steel.
After quenching, it is generally necessary to temper 3 times between 540 and 560 °C. Increasing the quenching temperature can increase the red hardness of the steel. In order to improve the service life of high-speed steel tools, the surface can be strengthened, such as low-temperature cyanidation, nitriding, sulfur-nitrogen infiltration, etc.
Second, the production process is different
1. The production of cemented carbide is to mix tungsten carbide and cobalt in a certain proportion, pressurize them into various shapes, and then semi-sinter. This sintering process is usually carried out in a vacuum furnace. It is placed in a vacuum furnace to complete the sintering, and the temperature at this time is about 1300 to 1500 degrees Celsius.
Cemented carbide sintering molding is to press the powder into a billet, and then enter the sintering furnace to heat to a certain temperature (sintering temperature), keep it for a certain time (holding time), and then cool it down to obtain a cemented carbide material with the required properties.
2. The heat treatment process of high-speed steel is more complicated, and it must go through a series of processes such as quenching and tempering. Quenching is generally carried out in two stages due to its poor thermal conductivity. First preheat at 800 ~ 850 ℃ (to avoid causing large thermal stress), then quickly heat to quenching temperature of 1190 ~ 1290 ℃ (the actual temperature of different brands is different), and then oil cooling or air cooling or gas cooling.
The factories are all heated by salt furnaces, and vacuum furnaces are also widely used. After quenching, a part (about 30%) of retained austenite remains in the internal structure and is not transformed into martensite, which affects the performance of high-speed steel. In order to transform the retained austenite and further improve the hardness and wear resistance, it is generally necessary to carry out 2 to 3 tempering times, the tempering temperature is 560 ° C, and the temperature is kept for 1 hour each time.