Effects of the Use of Master Alloys on the Sintering of Mn Steels

Abstract

When manufacturing sintered steel parts there is the option of adding alloying elements that improve the mechanical, functional, dimensional and wear properties of the component. This is the case of elements such as Mn or Si, which can provide a substantial improvement of the mechanical properties of a steel while maintaining a low cost given the abundance of these in the Earth's crust. Their use, however, is conditioned in the pulvimetallurgy industry given the affinity for oxygen shown by both elements, producing oxides that weaken the sintered components. One of the solutions developed to incorporate these elements into powder mixtures for sintering is the use of master alloys that allow the reduction of the chemical activity of the elements thus avoiding the formation of oxides. In this study, tests were carried out with four master alloys with different compositions of Mn and Si in order to study their behaviour during sintering and the properties they bring to sintered steel. With this objective, several mixtures containing different master alloys are prepared to produce sintered specimens at temperatures normally used in the manufacturing of sintered components. These specimens were used for the mechanical, chemical and microstructural characterization of steels, which will allow the study in greater depth the processes and changes that master alloy particles suffer during sintering, as well as understanding how these processes affect the properties obtained. A range of graphite additions were used in combination with the different master alloys in order to see how the presence of carbon in varying amounts affects the sintering mechanisms. The conclusions of this project paint a bigger picture of the behaviour of Mn and Si introduced in the form of master alloys and their interaction with the rest of the elements of the mixture. In addition, the manufacture of these specimens in industrial sintering conditions allows a first look at the viability of these master alloys for use in the manufacturing of sintered components