What are the effects of reduced iron powder on powder metallurgy?

1. Impurity content.

The iron scale is mainly used as raw material, which is made by washing, crushing, multichannel magnetic separation and reduction.
Influenced by sources of iron scale, manganese, silicon and other impurities can't effectively remove, in the process behind the manganese content in the finished powder 0.4 ~ 0.5% commonly, silicon content is more than 0.15%, acid insolubles content is over 0.40%.
These impurities are used as hard phase to aggravate the wear of mold during the process of powder forming and sintering.

2. The grain shape is not good.

The surface shape of the reduced iron powder directly influences the interchiming of the pressed particles, and the number of chimes determines the forming property to a large extent.
Iron powder manufacturers generally USES ordinary grinding equipment for crushing the iron scale and sponge iron, batch of equipment to a double cone mixer, destroyed at the same time in the crushing and mixing of particles on the surface of the topography, between the powder and the powder of occlusive become less, thereby reducing the formability of powder.

3. High oxygen and carbon content.

Iron powder reduction in 2 by reducing furnace sealing, protective atmosphere flow direction, the limitation of temperature control precision, etc, the final product oxygen content is in commonly 0.5%, carbon content is in commonly 0.05%, high content of carbon, oxygen, greatly reduces the powder repressive, and greatly affect the sintering activity, reduce the crushing strength;
It should be controlled under 0.3% and 0.02% respectively.

4. The weight of pine is high.

The particle size distribution of the powder has a great effect on the pine ratio.
Because because under the influence of grinding and particle size distribution, fine powder content in the iron powder in particular - 325 mesh sieve under pine than generally high, and volatile, brought instability to mass production.
In general, the proportion of the powder is added according to a certain grain size distribution, which guarantees the stability of the pine ratio and the fluidity.

5. Low oil content.

Iron powder particles inside the pore number and size directly affects the speed of oil bearing ability of oil storage and oil 5 iron scale reduced powder less internal pore and tiny, cross section of the porosity is generally 15 ~ 30%, and foreign porosity of reduced iron powder particles can reach above 40%.
For the average iron base bearing, considering the strength of the finished product, its density is generally 5.90~6.10g/cm3, the closed porosity of domestic powder is generally 6~8%, while the imported powder is 3.5~4.5%.

Improve the quality of reduced iron powder:

Reduced iron powder has been widely used in powder metallurgy. In order to obtain higher quality reducing iron powder, it is necessary to improve in the following aspects:

1. Improve the crushing equipment, develop the screw mixing machine, and keep the irregular shape of the particle surface as much as possible;
2. Ensure stable source of iron scale and have sufficient mixing capacity to improve the stability of batch;
3. Ensure that the proportion of fine powder is within the controllable range, and the low ratio can be obtained by increasing the proportion of coarse powder;
4. Improve ball milling process, reduce the content of flake powder, improve the internal porosity of particles and obtain larger pores;
5. Improve the packaging of finished product powder and reduce the oxidation and caking problems during transportation and storage.