Investigation of Sliding Friction of L63 Brass with Different Structural States

The objective of this study is to investigate the effect of heat treatment on the tribological properties of L63 brass with a structure formed after equal-channel angular pressing (ECAP).

The object of this study is L63 brass in various structural states and with distinct mechanical properties. The structure and properties were formed by severe plastic deformation using ECAP and low-temperature annealing. Transmission electron microscopy was used to examine the structure of the samples. Mechanical properties were evaluated under tension, and the hardness of the samples was determined. Sliding friction was measured using a ball-on-disk tribometer without the use of lubricants. The friction coefficient, vibration amplitude, and acoustic emission in the tribocontact were recorded. Metallography was used to study the state of the material's near-surface layer after friction. The friction surface and wear of the brass were studied using confocal laser scanning microscopy.

It was found that ECAP at room temperature increases the strength of L63 brass by 2.1—6 times and its nanohardness by 53—78 % relative to hot-rolled bar. Subsequent annealing reduces these values. The friction coefficient in the steel—brass pair after ECAP decreases by 7—11 %, and after annealing, it increases by 12—28 %, but remains 3—13 % lower than that of the original coarse-grained material. Wear resistance after 1—2 ECAP passes increases by ~ 40—47.5 %, while after 3 passes, it decreases by ~ 10 %. Annealing at 200 °C produces the greatest effect (wear resistance increases by 74—86 %), while annealing at 300 °C increases wear resistance by 36—68 % compared to the initial level. Vibrometry revealed a correlation between vibration acceleration amplitude, wear, and the friction coefficient, which is associated with wear particle formation and adhesive adhesion. The dominant wear mechanisms were found to be adhesive adhesion and fatigue failure affecting the mechanically mixed material layer.

1. Valiev R.Z., Islamgaliev R.K., and Alexandrov I.V. Bulk Nanostructured Materials from Severe Plastic Deformation // Progress in Materials Science. — 2000 (45), 103—189. https://doi.org/10.1016/S0079-6425(99)00007-9

2. Suryadi S., Napitupulu R.A.M., Dedi P., Suhadi A.S., and Siradj E.S. Effect of Equal Channel Angular Pressing and Post Heating on Microstructure and Hardness of Cu-Zn 70/30 // Advanced Materials Research. — 2013 (789), 373—378. https://doi.org/10.4028/www.scientific.net/AMR.789.373

3. Dutkiewicz J., Masdeu F., Malczewski P., and Kukuła A. Microstructure and Properties of α+β Brass after ECAP Processing // Archives of Materials Science and Engineering. — 2009 (39/2), 80—83

4. Song K.H., Kim H.S., and Kim W.Y. Enhancement of Mechanical Properties and Grain Refinement in ECAP 6/4 Brass // Reviews on Advanced Materials Science. — 2011 (28), 158—161

5. Kim H.S., Kim W.Y., and Song K.H. Effect of Post-Heat-Treatment in ECAP Processed Cu–40%Zn Brass // Journal of Alloys and Compounds. — 2012 (536), 200—203. https://doi.org/10.1016/j.jallcom.2011.11.079

6. Volokitina I.E. Effect of Preliminary Heat Treatment on Deformation of Brass by the Method of ECAP // Metal Science and Heat Treatment. — 2021 (63), 163—167. https://doi.org/10.1007/s11041-021-00664-y

7. Radhi H.N., Mohammed M.T., and Aljassani A.M.H. Influence of ECAP Processing on Mechanical and Wear Properties of Brass Alloy // Materials Today: Proceedings. — 2021 (44), 2399—2402. https://doi.org/10.1016/j.matpr.2020.12.461

8. Radhi H.N., Mohammed M.T., and Aljassani A.M.H. Development of Microstructure, Mechanical and Wear Characteristics of the Brass Alloy Processed by ECAP // Kufa Journal of Engineering. — 2024 (15), 1—15. https://doi.org/10.30572/2018/KJE/150201

9. Filippov A.V., Tarasov S.Yu, Fortuna S.V., Podgornykh O.A., Shamarin N.N., and Rubtsov V.E. Microstructural, Mechanical and Acoustic Emission-Assisted Wear Characterization of Equal Channel Angular Pressed (ECAP) Low Stacking Fault Energy Brass // Tribology International. — 2018 (123), 273—285. https://doi.org/10.1016/j.triboint.2018.03.023

10. Niels H. Hall–Petch Relation and Boundary Strengthening // Scripta Materialia. — 2004 (51), 801—806. https://doi.org/10.1016/j.scriptamat.2004.06.002

11. Alawadhi M.Y., Aloraier A.S., Alaskari A.M., Alazemi A.A., and Huang Y. Effects of Short-Term Annealing on the Thermal Stability and Microstructural Evolution of Oxygen-Free Copper Processed by High-Pressure Torsion // Materials. — 2024 (17), 5886. https://doi.org/10.3390/ma17235886

12. Hase A., Morita M., and Onodera K. Analysis of Seizure-Resistance-Improvement Mechanism of Polymer Additives by Acoustic Emission Sensing // Tribology International. — 2023 (184), 108441. https://doi.org/10.1016/j.triboint.2023.108441.

13. Olejnik P. and Desta Y.D. Friction-Induced Interactions: Acoustic Emissions, Vibrations, and Wear – a Multiscale Review // Nonlinear Dynamics. — 2025 (113), 24101—24140. https://doi.org/10.1007/s11071-025-11397-5

14. Filippov A.V., Rubtsov V.E., and Tarasov S.Yu. Acoustic Emission Study of Surface Deterioration in Tribocontacting // Applied Acoustics. — 2017 (117), 106—112. https://doi.org/10.1016/j.apacoust.2016.11.007

15. Popov V.L. Contact Mechanics and Friction. — Berlin, Heidelberg: Springer-Verlag. — 2010. https://doi.org/10.1007/978-3-642-10803-7

16. Tarasov S.Yu., Filippov A.V., Kolubaev E.A., and Kalashnikova T.A. Adhesion Transfer in Sliding a Steel Ball Against an Aluminum Alloy // Tribology International. — 2017 (115), 191—198. https://doi.org/10.1016/j.triboint.2017.05.039