Effect of Silicon on Microstructure and Wear Resistance of Fe-Mn-C-Si Self-lubricating Alloy

Self-lubricating Fe–Mn–C–Si alloys known as vernaloid alloys contain iron, manganese, carbon and silicon as active elements. These alloys have been widely used in structural components, gears, bearings and other structures that require excellent wear resistance and improved tribological properties. Silicon is an important alloying element in Fe–Mn–C–Si alloys and has a great influence on their corrosion and a capacity to form a protective film in contact with a surface. This element can also increase the strength and wear resistance of these alloys.
    
This article examines the effect of silicon on the microstructure and wear resistance of Fe–Mn–C–Si self-lubricating alloys. The research uses optical microscopy, scanning electron microscopy, and tribological properties testing of samples with different silicon contents. Microstructural studies revealed that the addition of Si, such as 0.18 wt. % and 0.25 wt. %, has no effect on the α–Fe matrix structure. However, it precipitates in the form of fine carbide particles, which improve the wear resistance of the alloy.
    
Shows an optical micrograph of an Fe–Mn–C–Si alloy with 0.18 wt. % silicon. The microstructure is characterized by a ferritic matrix containing evenly distributed fine carbide particles (darker spots). With the increase of the silicon content up to 0.25 wt. %, the distribution of the carbide phases became more compact and the size of the particles increased due to the formation of additional lamellar structures.
    
Shows a scanning electron micrograph of an Fe–Mn–C–Si alloy with 0.25 wt. % silicon. It is evident that the addition of silicon has caused the formation of more coarse carbide particles and their further accumulation in the ferrite matrix. The presence of these larger particles has improved the wear properties of the alloy.
    
The tribological properties of the alloys were tested using a reciprocating wear tester. Figure 3 presents the wear resistance of the Fe–Mn–C–Si alloys with different silicon contents. The results indicate that the addition of 0.18 wt. % and 0.25 wt. % silicon resulted in a significant improvement in the wear resistance of the alloys.
    
In conclusion, the addition of silicon to the Fe–Mn–C–Si self-lubricating alloys has a great influence on the microstructure and wear resistance. The decrease in silicon content resulted in a decrease in wear resistance, which indicates that silicon plays an important role in improving the tribological properties of these alloys. The results obtained in this study indicate that the addition of 0.18 wt. % and 0.25 wt. % silicon both improved the wear resistance of the Fe–Mn–C–Si alloys, with 0.25 wt. % silicon resulting in a greater improvement.

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