1. Superalloy turning tools
When turning superalloys with ordinary high-speed steel, the tool durability is very low. If high vanadium, high carbon, aluminum and cobalt high-speed steel is used, the tool durability will be relatively high. Cemented carbide is the main tool material for turning superalloys. YG cemented carbide with fine or ultra-fine particles shall be selected.
The rake angle of cemented carbide tools is generally about 10 °, and it is 0 ° - 5 ° during finish turning. Because the machinability of cast superalloys is worse, the rake angle should be smaller, about 0 °. The form of rake face is mostly linear arc and arc. In order to have better chip breaking effect. The work hardening of superalloy is serious, so the blade must be kept sharp, and no defects such as sawtooth are allowed. Generally, negative chamfering is not allowed. If it is necessary, it is smaller than cutting ordinary steel.
2. Cutting parameters
Turning superalloys also has a cutting speed corresponding to the optimal cutting temperature. The cutting speed of cutting superalloy with carbide turning tool is (10-60) m / min. Cast superalloys use a lower cutting speed, while deformed superalloys use a higher cutting speed. The cutting depth is (3-7) mm during rough turning and (0.2-0.5) mm during fine turning. In order to avoid cutting on the hardened layer, the feed rate should be greater than 0.1mm/r.
3. Cutting fluid
When turning superalloys, cutting fluid should be used, which can reduce the cutting temperature by about 25%. Water solution shall be used for high-speed steel cutting tools, and emulsion or extreme pressure cutting oil shall be used for cemented carbide cutting tools. Extreme pressure cutting fluid containing sulfur should not be used for nickel base superalloys to avoid stress corrosion and reduce fatigue strength.
4. Problems needing attention
Generally, cemented carbide should be used to turn superalloy as much as possible, and attention should be paid to the grinding quality of the tool to make the surface roughness of each tool surface less than 0.4 μ m. The blade shall be free of serration and other defects; In order to avoid cutting on the hardened layer, the cutting depth should be greater than 0.2mm, and the feed rate should be greater than 0.1mm/r; In order to keep the blade sharp and reduce work hardening, the tool blunt standard should be less than 0.2mm; When cutting with high-speed steel tools, the tool should be avoided from staying on the cutting surface to prevent the hardening of the cutting surface from intensifying, which will bring difficulties to the next cutting.