Abstract
Influence of manufacturing parameters (beam current from 13 to 17 mA, speed function 98 and 85) on microstructure and hydrogen sorption behavior of electron beam melted (EBM) Ti-6Al-4V parts was investigated. Optical and scanning electron microscopies as well as X-ray diffraction were used to investigate the microstructure and phase composition of EBM Ti-6Al-4V parts. The average α lath width decreases with the increase of the speed function at the fixed beam current (17 mA). Finer microstructure was formed at the beam current 17 mA and speed function 98. The hydrogenation of EBM Ti-6Al-4V parts was performed at the temperatures 500 and 650 °С at the constant pressure of 1 atm up to 0.3 wt %. The correlation between the microstructure and hydrogen sorption kinetics by EBM Ti-6Al-4V parts was demonstrated. Lower average hydrogen sorption rate at 500 °C was in the sample with coarser microstructure manufactured at the beam current 17 mA and speed function 85. The difference of hydrogen sorption kinetics between the manufactured samples at 650 °C was insignificant. The shape of the kinetics curves of hydrogen sorption indicates the phase transition αH + βH→βH.
Highlights
Titanium and its alloys are widely used as structural materials mainly in aerospace industry due to low density, corrosion and fatigue resistance, high-temperature strength, fracture toughness, and low Young’s modulus [1,2,3]
Hydrogen embrittlement is a serious problem for titanium alloy products because they are used in corrosive environments and are subjected to hydrogenation during operation [6,7,8,9,10]
The influence of manufacturing parameters on microstructure, phase composition, and hydrogen sorption kinetics of the Ti-6Al-4V parts produced by electron beam melting has been investigated
Summary
Titanium and its alloys are widely used as structural materials mainly in aerospace industry due to low density (light weight), corrosion and fatigue resistance, high-temperature strength, fracture toughness, and low Young’s modulus [1,2,3]. Two-phase (α + β) titanium alloys are used to produce such critical and loaded parts as discs, working and guide blades, compressor rings, and other components. The operating temperatures of titanium alloys in aircraft engines vary from 120 to 580 ◦ C [4,5]. During operation in aggressive environments containing hydrogen and oxygen at high temperatures, the physical and mechanical properties of titanium alloys significantly deteriorate. Hydrogen embrittlement is a serious problem for titanium alloy products because they are used in corrosive environments and are subjected to hydrogenation during operation [6,7,8,9,10]. Hydrogen absorbed by the products precipitates as a brittle hydride phase, leading to degradation of mechanical properties of titanium-based alloys.
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