In the field of high-end manufacturing, M42 alloy powder has become the core material for cutting tools, aerospace components and precision molds due to its excellent red hardness, wear resistance and high temperature strength. However, its performance is highly dependent on composition design and process control. Among them, the addition amount of WC (tungsten carbide) as a key variable directly affects its microstructure and properties. This article did some investigation on the effect of WC addition on the performance of M42 alloy powder, revealing its key role in heat treatment, sintering process and composite material design.
Effect of WC addition on hardness of M42 powder
As-Sintered:
The effect of WC addition on hardness after sintering shows a trend of first decreasing and then increasing. When the WC content is 5%, the hardness decreases by about 9.83% (lower than M42 without WC addition); and when the WC content increases to 10%, the hardness increases significantly by 13.2 HRC, exceeding the hardness of M42 powder without WC addition.
As-heat treated:
The sintered parts are heat treated through 1180℃ quenching and 560℃ tempering, the hardness reaches a maximum value of 65.1 HRC when the WC addition is 10%, indicating that heat treatment can effectively optimize the effect of WC on improving hardness.
Microstructure evolution
Carbide distribution:
When the WC content is low (2%), the carbides in the matrix are reduced, but network carbides appear; when the WC content is medium (5%), the carbides are concentrated at the grain boundaries, resulting in aggregation and growth; when the WC content is high (10%), the carbides are further aggregated, but secondary carbides (such as M7C3) are precipitated after heat treatment, forming dispersion strengthening.
| SEM images of WC/M42 composites with different WC% |
Sintering density:
When the amount of WC added increases (0-10%), the relative density of the sintered composite material first increases and then tends to stabilize.
| Density of WC/M42 composites with different WC% under different sintering temperature |
Conclusion:
When WC addition amount is 8-10%, WC/M42 composites are suitable for the application with high hardness and wear resistance requirements (such as milling cutters and drill bits), but strength and toughness need to be optimized through heat treatment.
When WC addition is less than 8%, it can avoid the expansion of brittle phase caused by carbide aggregation and ensures high temperature strength and stability. It is more suitable for the application at high temperature.
Future trends:
Develop WC/TiC-M42 gradient material to balance hardness and toughness.
Optimize ball milling/sintering parameters, predict carbide size and distribution, and achieve precise control of carbide size and distribution.
Design WC/M42 composite powders specifically for additive manufacturing.
