研究目的
Investigating the mechanical and metallurgical properties of fiber laser welded Nb-1% Zr-0.1% C alloy.
研究成果
Laser welding of the reactive and highly conductive of Nb-1%Zr-0.1%C alloy was attempted with the double-sided gas shielding. Mechanical and metallurgical properties were evaluated for both the base metal and the welded joints. The significant increase in the microhardness value of the welded joints was due to the formation of brittle oxides, and carbides phases along with refined grains in the fusion zone. The marginal reduction in tensile strength and ductility of the welded joints as compared to that of the base alloy was due to the enhancement of hardness and brittle phase’s density in the fusion zone. A set of optimized power and beam diameter along with high level of welding speed was found to be suitable for the enhancement of aspect ratio of laser welded thin niobium alloy (sheet).
研究不足
The technical and application constraints of the experiments include the reactivity of niobium alloy in ambient atmosphere, which limits the welding process to be carried out in controlled environment. Potential areas for optimization include the optimization in laser welding of Nb-1%Zr-0.1%C, where mechanical properties are found to be conflicting in nature.
1：Experimental Design and Method Selection:
Laser welding of Nb-1% Zr-0.1% C was attempted in butt-welding configuration using top and bottom sided inert gas shielding. The ranges of input parameters for full penetration welding were attempted by carrying out bead-on-plate (BOP) experiments.
2：1% C was attempted in butt-welding configuration using top and bottom sided inert gas shielding. The ranges of input parameters for full penetration welding were attempted by carrying out bead-on-plate (BOP) experiments.
Sample Selection and Data Sources:
2. Sample Selection and Data Sources: Thin sheets of Nb-1% Zr-0.1% C alloy were used. These sheets were manufactured by taking homogeneous powder mixture of niobium, zirconium and carbon powders with trace amount of impurities by isostatic pressing, followed by sintering, forging, cold/hot rolling and annealing.
3：1% C alloy were used. These sheets were manufactured by taking homogeneous powder mixture of niobium, zirconium and carbon powders with trace amount of impurities by isostatic pressing, followed by sintering, forging, cold/hot rolling and annealing.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Yb-fiber laser (IPG YLR-2000) operating at 1.064 μm and maximum power of 2 kW, Scanning electron microscope (SEM) (EVO 15, Zeiss, Jena, Germany) coupled with EDAX(AMETEK), X-ray diffractometer PANalytic Empyrean Cu LFF HR (9430 033 7310x) DK411025, Netherlands) generating Cu Kα radiation, Hardness tester (OMNITECH MVH-S-AUTO).
4：064 μm and maximum power of 2 kW, Scanning electron microscope (SEM) (EVO 15, Zeiss, Jena, Germany) coupled with EDAX(AMETEK), X-ray diffractometer PANalytic Empyrean Cu LFF HR (9430 033 7310x) DK411025, Netherlands) generating Cu Kα radiation, Hardness tester (OMNITECH MVH-S-AUTO).
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: Prior to real butt welding experiments, Bead-on-plate (BOP) experiments were carried out to obtain the ranges of input parameters for obtaining the full-penetration weld. The weld-bead geometry, i.e., penetration depth and weld-width were analysed for each combination of input parameters for BOP welds.
5：Data Analysis Methods:
The mathematical relationship between tensile strength and input process parameters data was given. A second-degree polynomial fit between microhardness (H) and tensile strength (TS) data was plotted.
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