Cemented carbide is made by powder metallurgy. It uses metal carbides (tungsten carbide WC, titanium carbide TiC, tantalum carbide TaC, and niobium carbide NbC, etc.) with high hardness and melting point as hard phase, and metal cobalt, aluminum or nickel as bonding phase. It is made into powder, mixed in a certain proportion, pressed into shape, and sintered under high temperature and high pressure.
Since the content of high melting point and high hardness carbides in cemented carbide far exceeds that of high-speed steel, the room temperature hardness of cemented carbide is very high (89~93HRA is equivalent to 78~82HRC), the melting resistance is good, the hot hardness can reach 800℃~1000℃ or more, and the allowed cutting speed is 4~7 times higher than that of high-speed steel. It is the main tool material used in cutting processing second only to high-speed steel. However, the bending strength of ordinary cemented carbide is only 1/3~1/2 of that of high-speed steel, and the impact toughness is only 1/35~1/4 of that of high-speed steel (i.e., it is more brittle), so its ability to withstand impact and bending is relatively low.
The mechanical properties of cemented carbide are mainly determined by the type, quantity, powder particle size and binder content of the carbide that constitutes the cemented carbide. The higher the hardness and melting point of the carbide, the better the hot hardness of the cemented carbide. Since the hardness and melting point of carbide as a hard phase are much higher than those of the binder, the more carbide content in the cemented carbide, the higher the hardness, but the lower the bending strength. If the binder ratio increases, the strength and toughness are better. In addition, when the binder content is constant, the finer the carbide powder, the thinner the bonding layer, which is equivalent to a relative reduction in the binder, which increases the hardness and reduces the bending strength. If the carbide powder is refined without reducing the thickness of the bonding layer, the purpose of increasing the hardness without reducing the bending strength can be achieved.
The application range of common cemented carbide
| Brand | Performance | Application Range |
| YG3 | Among YG alloys, its wear resistance is second only to YG3X and YC6A. It can use higher cutting speeds, but is sensitive to impact and vibration. | Suitable for continuous finishing and semi-finishing of cast iron, non-ferrous metals and their alloys, and non-metallic materials |
| YG3X | It is a fine-grained alloy, the best wear-resistant type among YG alloys, but its impact toughness is poor. | Suitable for finishing and boring of cast iron, non-ferrous metals and their alloys, and also suitable for finishing of hardened steel and tungsten materials |
| YC6 | It has high wear resistance, but lower than YC6X, YG3X and YG3. | Suitable for rough turning during continuous cutting, semi-finishing and finishing during intermittent cutting of cast iron, non-ferrous metals and their alloys, and non-metallic materials |
| YC6X | It is a fine-grained alloy, its wear resistance is higher than YC6, and its service strength is close to YC6. | Suitable for machining of cold cast iron, alloy cast iron, and heat-resistant steel, and also suitable for finishing of ordinary cast iron, and can be used to manufacture small tools for machine instrument industry |
| YG8 | It has higher service strength, better impact and vibration resistance than YC6, and lower wear resistance and allowable cutting speed. | Suitable for rough machining of cast iron, non-ferrous metals and their alloys, and non-metallic materials |
| YG8C | It is a coarse-grained alloy, with higher service strength, close to YGI1. | Suitable for Turning tools, planing tools, etc. under heavy-load cutting |
| YG6A | It is a fine-grained alloy, and its wear resistance and service strength are similar to YC6X. | Suitable for semi-finishing of hard cast iron, gray cast iron, ductile iron, non-ferrous metals and their alloys, and heat-resistant alloy steels. It can also be used for semi-finishing and finishing of high manganese steel, hard steel, and alloy steels |
| YT5 | It has higher strength, best impact and vibration resistance, but poor wear resistance among YT alloys. | Suitable for rough turning, rough planing, semi-finishing planing, rough milling, and drilling of discontinuous surfaces of carbon steel and alloy steel |
| YT14 | It has high service strength, good impact and vibration resistance, but slightly worse than YT5, and higher wear resistance and allowable cutting speed than YT5. | Suitable for rough turning of carbon steel and alloy steel, semi-finishing and finishing during intermittent cutting, and rough milling of continuous surfaces |
| YT15 | It has better wear resistance than YT14, but the impact toughness is worse than YT14 | Suitable for rough turning, semi-finishing and finishing during continuous cutting, section finishing during intermittent cutting, and finishing and semi-finishing milling of continuous surfaces in the processing of carbon steel and alloy steel |
| YT30 | Wear resistance and allowable cutting speed are higher than YT15, but the use strength and impact toughness are poor, and cracks are easily generated during welding and grinding | Suitable for finishing of carbon steel and alloy steel, such as small section finishing, finishing boring, finishing expansion, etc. |
| YW1 | The use performance of YT alloys has been expanded, and it can withstand certain impact loads and has good versatility | Suitable for finishing of difficult-to-process materials such as heat-resistant steel, high manganese steel, stainless steel, and also suitable for finishing of general steel, cast iron and non-ferrous metals |
| YW2 | The wear resistance is slightly inferior to YWI alloy, but the use strength is higher and can withstand greater impact loads | Suitable for finishing and semi-finishing of difficult-to-process steels such as heat-resistant steel, high manganese steel, stainless steel and high-grade alloy steel, and also suitable for finishing of general steel, cast iron and non-ferrous metals |
| YN1O | Good wear resistance and heat resistance, hardness is equivalent to YT30, strength is slightly higher than YT30, welding performance and grinding performance are better than YT30 Good | Suitable for continuous surface finishing of carbon steel, alloy steel, stainless steel, tool steel and hardened steel. The processing effect is particularly good for longer parts and parts with small surface roughness requirements |
| YNO5 | Hardness and wear resistance are the highest among cemented carbides, and wear resistance is close to ceramics, but impact resistance and vibration resistance are poor | Suitable for high-speed finishing T of steel, hardened steel, alloy steel, cast iron and alloy cast iron, and finishing of slender parts with particularly good process system rigidity |
Generally speaking, the relationship between wear resistance and toughness of cemented carbide is contradictory: the improvement of wear resistance will lead to the reduction of toughness, while the improvement of toughness will inevitably lead to the reduction of wear resistance. Therefore, when selecting alloy grades, it is necessary to meet specific use requirements according to the processing object and processing working conditions.
If the selected grade is prone to early cracking and damage during use, it is advisable to select a grade with higher toughness; if the selected grade is prone to early wear and damage during use, it is advisable to select a grade with higher hardness and better wear resistance. The following grades: YG15C, YG18C, YG20C, YL60, YG22C, YG25C from left to right, the hardness decreases, the wear resistance decreases, and the toughness increases; vice versa, the opposite is true.
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