Effects of the Processing Parameters of Friction Stir Processing on the Microstructure, Hardness and Tribological Properties of SnSbCu Bearing Alloy

Abstract

In the study, the friction stir processing (FSP) method was used to modify the surface layer of a tin-based bearing alloy. The modification was aimed at extending the service life of bearings by improving their tribological properties. The results of investigations of the microstructure, hardness and tribological properties of the SnSbCu bearing alloy after FSP using various rotational speeds of the tool—280, 355, 450 and 560 RPM—and the constant traverse speed of 355 mm/min are presented. Particular attention was paid to the possibility of changing the morphology of the precipitates present in the alloy, and to the impact of this parameter on improvement of the tribological properties. The research carried out in this paper covered investigations of the microstructure using light and scanning electron microscopy (SEM) along with analysis of the chemical composition in micro-areas and Brinell hardness tests. Additionally, the sizes of the SnSb and CuSn precipitates present in the microstructure before and after the modification process were determined, as were the tribological properties under technically dry friction conditions and lubrication with TU 32 oil. It was proven that using friction stir processing favors refinement of the microstructure and improves the tribological properties of the analyzed alloy.

Effect of FSP on Tribological Properties of Grade B89 Tin Babbitt

“…The analysis of the average values of the coefficient of friction presented in Figure 11 confirms that the application of FSP modification reduces its value, regardless of the applied parameters of the tribological test, especially in conditions of intermittent friction, which can be extremely advantageous in friction pairs operating intermittently and the possible design problem associated with the continuous supply of oil to the friction pair. In the case of the B89 alloy, there is a stronger effect of FSP than in the case of the B83 alloy, which was demonstrated in the studies presented in publication [ 26 ].…”

“…In a relatively short time since its invention [ 15 ], FSP technology has found many applications, both for modifying and improving the properties of foundry products [ 16 , 17 , 18 , 19 ], sinters obtained by powder metallurgy technology [ 20 ], as well as for introducing additional materials into the surface layers of a processed material (friction stir alloying—FSA) [ 21 , 22 ]. Dynamic recrystallization, which takes place in the process zone during modification with the FSP method [ 23 , 24 ], leads to microstructure refinement, increases fatigue strength [ 19 ] and improves mechanical [ 16 , 17 ] and tribological [ 25 , 26 ] properties.…”

“…The conducted tribological tests allowed the authors to determine how the change in the morphology of the precipitates present in the alloy affects the wear resistance and the course of friction. Earlier studies by the authors on the B83 alloy [ 26 ] modified by FSP with the use of the Triflute tool proved the improvement of the tribological properties as a result of refinement of the hard phases present in the alloy after FSP modification. This article focuses on the characteristics of the tribological properties of the B89 alloy after FSP modification using the Whorl tool with a different geometry.…”

Characterization of microstructure and selected properties of SnSbCu alloy after FSP

“…The results concerning various materials such as aluminum alloys presented in the literature were so promising that an attempt was made to implement this method also for the most popular grades of tin-based bearing alloys. The results of the research on the use of the FSP method to modify the SnSb11Cu6 alloy were published in [22]. It has been proved, among others, that the FSP modification of the SnSb11Cu6bearing alloy using the Triflute tool improves the tribological properties as a result of the refinement of hard phases present in the alloy.…”

Characterization Of Microstructure And Selected Properties of SnSbCu Alloy After FSP

“…To date, only one work has been published in this eld. It was proved, among others, that FSP modi cation of the SnSb11Cu6 bearing alloy with the Tri ute tool promotes improvement of the tribological properties as a result of re nement of the hard phases present in the alloy [15]. This article focuses on the characteristics of the microstructure of the SnSbCu alloy containing, respectively, approx.…”