Effect of grain size on the micro-tribological behavior of pure titanium processed by high-pressure torsion

• Published in: Wear Vol. 280-281; pp. 28 - 35
• Main Authors: Wang, Chuan Ting, Gao, Nong, Gee, Mark G., Wood, Robert J.K., Langdon, Terence G.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 20.03.2012; Elsevier
• Subjects: Abrasive wear; Applied sciences; Debris; Exact sciences and technology; Friction, wear, lubrication; Fundamental areas of phenomenology (including applications); Grain size; High-pressure torsion; Inelasticity (thermoplasticity, viscoplasticity...); Machine components; Mechanical engineering. Machine design; Physics; Solid mechanics; Structural and continuum mechanics; Surface plastic deformation; Titanium; Torsion; Wear; Wear mechanisms; Wear particles; Wedge forming; Wedges; PBS; CG; SPD; High-pressure torsion; Surface plastic deformation; AFM; CP; HPT; IFM; Abrasive wear; Wedge forming; UFG; Titanium; MEMS; SEM; COF; TEM; OM; Grain size; Wedge; High pressure; Inelasticity; Dynamic contact; Two body system; Wear rate; Size effect; Plasticity; Friction coefficient; Surface deformation; Fine grain structure; Tribology
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/j.wear.2012.01.012

► Grain size of pure Ti was reduced to ∼130nm from ∼8.6μm using high pressure torsion (HPT). ► Microhardness was improved from 182 HV1 to 305 HV1. ► Micro wear behavior of HPT processed Ti was studied for the first time. ► Wear of coarse grained Ti was dominated by ploughing and wedge forming, while wear of HPT processed Ti was dominated by abrasion. ► HPT processed Ti has more homogeneous wear scar and lower wear rate. The micro-wear behavior of commercial pure Ti was investigated before and after processing by high-pressure torsion (HPT) to provide comparisons over a range of grain sizes. The HPT-processed Ti had an average grain size of ∼130nm while the as-received and HPT plus annealed samples had grain sizes of ∼8.6μm and ∼607nm, respectively. The results show all Ti samples have a similar dynamic coefficient of friction but different wear mechanisms. Wear of the coarse grained (CG) Ti showed extensive plastic deformation and wedge formation which produced large wear debris whereas wear of the ultra-fine grained (UFG) Ti was dominated by abrasive wear mechanisms and produced small wear debris. In addition, the UFG Ti showed a more homogenous wear grooving and a lower wear rate than CG Ti which suggests that UFG Ti is more suitable for wear applications.