PSI - Issue 59

Sviatoslav Motrunich et al. / Procedia Structural Integrity 59 (2024) 58–65 Sviatoslav Motrunich et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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So, the main aim of this research was to improve the production technology of titanium alloy ingots for medical applications through electron beam cold hearth melting of Ti-Al- Nb alloy and study it’s microstructure, mechanical properties and fatigue behavior. 2. Experimental procedure 2.1. Electron beam cold hearth melting Research on electron beam melting of Ti-Al-Nb alloy ingots in order to improve the production technology of titanium alloys ingots for medical use was carried out. An electron beam unit UE208M, well described by Markovsky (2022), was used for experimental melting of Ti-Al-Nb alloy ingots with 110 mm diameter (Fig. 1.a). During the melting process, the following technological parameters were controlled: the accelerating voltage of the

a

b

Fig. 1.Obtained ingots of Ti-Al-Nb alloy: (a) as-melted ingot, (b) after machining.

electron beam guns, the beam currents, the rate of supply of the initial charge to the melting zone, the rate of extraction of the ingot from the crystallizer, the temperature of the cooling water. Based on previously fundamental studies of the evaporation processes of alloying components during melting in a vacuum charge material composition was calculated. The charge material consists of previously obtained slab of titanium sponge TG-100 with alloying components in the form of pure niobium and primary aluminum (Fig. 1.b). Established technological parameters of EBCHM process used for melting are given in Table 1.

Table 1. Technological parameters of EBCHM process Technological parameters

Values 20 kg/h 10 mm 16 kW 80 kW

Melting speed

The height of portions simultaneously poured into the crystallizer

Power in the crystallizer Power in the intermediate tank

2.2. Ingot quality study procedure Obtained ingots were cooled in a vacuum to a temperature below 300°C. The side surface of molten ingots was clean. There was no increased concentration of impurity elements on the surface in the form of an oxidized or alpha layer (Fig. 2.a). There were no surface defects in the form of breaks, cracks or non-fusion. The depth of surface defects of the "corrugation" type is 1...3 mm. Also, considering the small size (110 mm diameter) of obtained Ti-Al Nb alloy ingot, it was subjected to mechanical surface treatment on a lathe. The surface layer was removed to a depth of no more than 3 mm per side and the ends was machined (Fig. 2.b).