Effect of sintering atmosphere on the microstructure of high carbon iron based powder metallurgy materials

The influence of sintering atmosphere (propane cracking and ammonia decomposition) on the microstructure of the Fe–Cu–0.8%C alloy products sintered by powder metallurgy technology was studied. The results show that the decarburization are present on the surface of high-carbon products sintered in propane cracking atmosphere, and the product hardness on the surface is lower than that in the core by HV_0.1 40. Carbon compensation can be carried out by adding gas flow, but the network cementite may appear in the part of products because of the uneven compensation, affecting the product performance. There is no obvious decarburization on the surface of the products sintered in decomposed ammonia atmosphere, the optimal microstructure can be obtained by compensating gas flow as 5~10 L·h⁻¹, and the hardness on the surface and in the core of the products are basically the same.