EFFECTS OF MAJOR IMPURITY ELEMENTS ON COMPRESSIBILITY OF WATER-ATOMIZED IRON POWDER

Abstract

Compressibility is one of the most important properties of iron powder for powder metallurgy applications. Understanding effects of chemical impurity elements on compressibility of the iron powder and differentiating contribution of each impurity element are critical for the iron and steel powder enterprise to select approaches to control and improve compressibility of the powder. In this work 500 water-atomized iron powder samples are chosen and effects of the main impurity elements like C, Si, Mn, P, and S and hydrogen loss (HL) reflecting oxygen on compressibility of the iron powder are quantitatively studied. First, effect of single impurity element on the compressibility is investigated. Linear regressions show the degrees of regression are very low even with sample number increase up to 500 implying uncertainty of the single factor regressions due to the instable content of the other impurities when the effect of one impurity element is concentrated on. Then, a multiple factor regression is established taking into account all the six impurity elements as a whole. The degree of regression improves to as high as 0.9746 with sample number increase to 500 and dependency of compact density Y on the six impurity elements can be expressed as: Y = 7,1442 – 0,4231 x C% – 0,0498 x Si% – 0,0988 x Mn% – 3,2784 x P% – 0,2577 x S% – 0.1220 x HL%. This equation manifests the negative effects of all the six impurity elements on compressibility of the water-atomized iron powder by P and C mostly, Mn, S, and HL moderately, and Si least.