研究目的
Investigating the plastic anisotropy of laser melting deposited Ti–5Al–5Mo–5V–1Cr–1Fe titanium alloy through tensile tests in different orientations and analyzing the mechanical properties with respect to specified material structures.
研究成果
The mechanical properties of the LMD TC18 titanium alloy show significant plastic anisotropy. The elastic modulus E could be regarded as elastic isotropic basically, but the yield strength σ0.2 and tensile strength σb show significant anisotropy and are roughly symmetrical about θ=45°. The ductility δ increases obviously with the increase of θ when θ ≥ 30°. The thick columnar grain yields firstly and bears the main plastic deformation of the whole specimen under the same stress level. The microstructure of layer bands and the direction of αp laths on both sides have a significant influence on the plastic properties of LMD TC18 titanium alloy.
研究不足
The study focuses on the plastic anisotropy and mechanical properties of LMD TC18 titanium alloy, but the effects of other factors such as temperature variations and different heat treatment processes on the material's properties are not explored.
1：Experimental Design and Method Selection
Tensile experiments were designed and implemented referring to ISO 6892-1:2016. Ordinary tension tests at multiple angles were conducted to measure the overall mechanical properties with respect to the specified orientations. In-situ tension tests under a metalloscope combined with digital image correlation (DIC) method were conducted to study the mechanical properties with respect to specified material structures, i.e., columnar grains and layer bands.
2：Sample Selection and Data Sources
The material used in this study was fabricated by LMD technique. The original build-up material is a thick plate with geometric dimensions of 300 mm×100 mm×40 mm. All specimens were extracted from the middle part with a nominal thickness 1 mm.
3：List of Experimental Equipment and Materials
INSTRON 8801 servo-hydraulic fatigue test system combined with an extensometer, ZEISS AxioScope metalloscope, CARE Measurement & Control Co IBTC-5000 In-situ tensile testing machine, VIC-2D Digital Image Correlation software, ZEISS AxioScope optical microscope (OM), JSM 6010 scanning electron microscope (SEM).
4：Experimental Procedures and Operational Workflow
All specimens were prepared by the conventional mechanical polishing method. The observation surface of in-situ tension specimens was also etched. Step by step displacement loading was used for in-situ tension tests.
5：Data Analysis Methods
Digital image correlation method was used to measure the deformation in different zones with specified microstructures under static stretching loading.
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