WATER ATOMIZED PURE IRON POWDER AND ITS PROPERTIES

The present paper has described the process of water atomized pure powder(PFT iron powder). Iron powder (called green powder) was obtained by the high pressure water atomization of melts of carbon steel scrap at 1600℃ wtichas as raw materials was melted and meanuhils recarburizer was added.High pressure water atomization unit is of non-closed system. The nozzle is of v-shope structure. The water pump has a high pressure of 5.9MPa and a water flow of 25 T/h. The chemical compositions, particle sizes and morphology of powder can be controlled by adjusting the temperatures, flow rates and carbon contents of liquid iron, the parameters of nozzle structure, the flow rate of high pressure water and the cooling conditions of atomized powder. Then the PFT iron powder is obtained after drying, annealing, crushing and sieving,
The present paper has discussed the processing factors to obtain PFT iron powder with low oxygen contents (≤ 2000ppm). The relations of carbon and oxygen contents between powder after annealing and as-atomized powder are given. Experiments have shown PFT iron powder with low oxygen contents can be obtained by one step of annealing when the rate between carbon and oxygen in iron powder is controlled in a given range by adjusting the melting and water atomizing parameters.
The chemical compositions, physical properties, morphology and inner structures of PFT iron powder are compared with those of Japanese KIP300A iron powder west German WPL 200 iron powder. It is the superior raw material which is suitable for producing structural parts with medium or high strength. Obvious economic results have been obtained by using PFT iron powder to make sintered steel gears for type 175F-1 diesel.