Mixed steel powder containing mn for powder metallurgy and preparation method thereof

Abstract

The invention discloses Mn-contained mixture steel powder for powder metallurgy and a preparing method. The Mn-contained mixture steel powder is composed of water atomization pure iron powder, Mn-contained water atomization pre-alloyed steel powder, FeMn alloy powder, graphite powder and a lubricant, wherein the mass percentage content of Mn is lower than or equal to 3%. The preparing method includes the steps of preparing the components and mechanically and evenly mixing the components. The pressing performance and the sintered density of the prepared mixture steel powder are superior to the pressing performance and the sintered density of the Mn-contained water atomization pre-alloyed steel powder with the same components, and compared with a finished product obtained by sintering conventional Mn-contained mechanical mixture powder with the same contents, a sintered finished product is lower in oxygen content and high in density. The content of the Mn can be as high as 3%. The Mn-contained mixture steel powder is reasonable in component matching and high in Mn content, the prepared Mn-contained mixture steel powder combines the advantages of even Mn-element distribution in the Mn-contained pre-alloyed steel powder and the good pressing performance of the conventional Mn-contained mechanical mixture powder, the pressing performance is good, the sintered finished product is low in oxygen content and high in density, and the Mn-contained mixture steel powder is suitable for industrial production.

Description

technical field [0001] The invention relates to a Mn-containing mixed steel powder for powder metallurgy and a preparation method thereof, belonging to the technical field of powder metallurgy. Background technique [0002] Due to its advantages of energy saving, material saving, and near-net shape, powder metallurgy technology is widely used in the preparation of metal parts in industrial production, of which iron-based powder metallurgy materials account for the vast majority. Due to the needs of industrial applications, simply using water-atomized pure iron powder as the raw material for the production of iron-based powder metallurgy materials cannot meet the final performance requirements, so it is usually added to water-atomized pure iron powder by mechanical mixing or pre-alloying Alloying elements to improve its properties. Water atomized pure iron powder contains a small amount of Mn, which is brought in from iron ore, and its content is generally not higher than 0....

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Problems solved by technology

But this method also has the following problems: the Mn element is easy to combine with oxygen in the smelting water atomization preparation process, and when the Mn content is high, the oxygen content of the Mn-containing water atomized pre-alloyed steel powder is high, and because the Mn element has an effect on the pre-alloyed steel powder The strengthening effect of Mn-containing water atomized pre-alloyed steel powder has high hardness and lower compaction performance than that of Mn-containing mechanically mixed powder with the same composition. Higher requirements for presses and pressing molds, increasing production costs

However, under industrial production conditions, due to the high dew point of the sintering atmosphere (-30°C to -25°C), the activity of FeMn alloy or electrolytic manganese powder is high. It has been reported that when the mass percentage of Mn exceeds 2%, the mechanical In the position of FeMn alloy or electrolytic manganese powder inside the compact made of mixed powder, during the degreasing and heating process before high-temperature sintering, Mn evaporates, oxidizes and deposits on the adjacent iron-based powder particles, and is easy to connect to form a Mn-containing oxide network. Once the oxide network is formed, in the subsequent high-temperature sintering process, the sintering atmosphere cannot permeate and diffuse into the oxide network to reduce the internal oxide, resulting in high oxygen content in the final sintered product, which has a negative effect on sintering densification and The mechanical properties of the products all have negative effects. In severe cases, the Mn-containing oxides can split the matrix and be brittle when loaded, causing immeasurable serious consequences.

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