PSI - Issue 2_A

Alexander Nikitin et al. / Procedia Structural Integrity 2 (2016) 1125–1132 Author name / Structural Integrity Procedia 00 (2016) 000–000

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mm/min. The results of monotonic quasi-static tensile tests are the following: UTS = 1107 MPa,  Y = 1050 MPa, elongation at rupture = 13 %, E=106 GPa and the dynamic modulus at 20 kHz is E D = 106 GPa. Before any mechanical tests the bars of this titanium alloy were treated in the way that provides a fully lamellar needle-like microstructure, Figure 1. The previous mechanical properties were determined on the treated alloy. Alpha-phase platelets are in white and beta-phase is in black on this figure. The alpha-platelets are elongated in the direction of extrusion and have characteristic length of 2 micrometers. Cross section of these platelets has an almost circular geometry, figure 1a.

Fig. 1. Microstructure of extruded VT3-1 titanium alloy on planes (a) perpendicular and (b) parallel to extrusion direction.

At some locations the microstructure exhibits very thin alpha-platelets with a length of about 10 micrometers. The microhardness of the extruded VT3-1 titanium alloy was measured by the Vickers method with the following parameters: force 500 N, indentation time: 10 sec. Microhardness values were measured automatically at 15 different locations along a straight line on two planes (perpendicular and parallel to the extrusion direction). The results show almost the same microhardness mean values on the two planes: 374 HV 500 and 371 HV 500 on the planes perpendicular and parallel to the extrusion direction respectively. The scatter is very small: the maximum deviation from the mean value is 8 HV 500 .

1.1.

Specimens

Fig. 2. Geometry of (a) tensile and (b) torsion ultrasonic fatigue specimens in extruded VT3-1 alloy.