A study on the hardness variation of α- and β-pure titanium with different grain sizes

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2005-05, Vol.398 (1-2), p.93-98
• Main Authors: Kao, Y.L., Tu, G.C., Huang, C.A., Liu, T.T.
• Format: Article
• Language: English
• Subjects: Applied sciences; CP α- and β-titanium; Exact sciences and technology; Grain size; Hardness; Martensite strengthening; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2005.03.004

In this study, the hardness and the microstructure of α- and β-pure Ti treated with different grain sizes were investigated. The α-Ti specimens were obtained by heating pure Ti at 750°C for various periods and then quenched in water, while the β-Ti specimens by heating at 1000°C for various periods and then quenched in water. Experimental results show that the hardness of α-Ti decreased with increasing the grain size; whereas, the hardness of β-Ti tends to increase with increasing grain size. From the microstructures examined with transmission electron microscope, it can be realized that the strengthening mechanisms of α- and β-Ti are quite different. Grain boundary could be the main strengthening microstructure of α-Ti and the smaller grain size the higher hardness. The major strengthening microstructure of β-Ti was martensitic twin with a very high dislocation density. The amount of martensitic twin increased with increasing the grain size of β-Ti and, therefore, the larger grain size the higher hardness.