scholarly journals Contrastive Studies between Laser Repairing and Plasma Arc Repairing on Single-Crystal Ni-Based Superalloy

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1172 ◽  
Author(s):  
Cheng Wang ◽  
Qiuliang Li ◽  
Xin Zhou ◽  
Wenxin Zhu ◽  
Runqiu Huang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Epitaxial Growth ◽  
Young’S Modulus ◽  
Fusion Zone ◽  
Melting Process ◽  
Plasma Arc ◽  
Transition Phenomenon ◽  
Microstructures And Mechanical Properties ◽  
Columnar To Equiaxed Transition

Laser repairing and plasma arc repairing experiments on the single-crystal Ni-based superalloy DD407(Ni-7.82Cr-5.34Co-2.25Mo-4.88W-6.02Al-1.94Ti-3.49Ta in wt.%) were carried out in this paper, and the differences in microstructures and mechanical properties varying with depth between the two repairing methods were studied. Comparing the two repairing processes, both the fusion zone can maintain single-crystal epitaxial growth with no significant cracks and have similar fine γ′ precipitates. Nevertheless, the columnar-to-equiaxed transition phenomenon occurred on the top of the fusion zone during the laser re-melting process but was not very obvious on the top surface of the fusion zone during the plasma arc re-melting process. In addition, both the DD407 superalloy conducted with the two repairing processes had a large microhardness and a great Young’s modulus in the fusion zone.

scholarly journals Fiber Laser Surface Melting of a NiTi Superelastic Alloy: Influence on Structural and Mechanical Properties

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1268 ◽  
Author(s):  
David Dias ◽  
Osmar Santos ◽  
Wellington Alves ◽  
Milton Lima ◽  
Maria Silva
Keyword(s):  
Mechanical Properties ◽  
Fusion Zone ◽  
Laser Fluence ◽  
Melting Process ◽  
Surface Melting ◽  
Laser Surface ◽  
Laser Surface Melting ◽  
Surface Finishing ◽  
High Laser Fluence ◽  
High Laser

The surface melting of a NiTi superelastic alloy using a high-power laser Yb:Fiber was investigated. The influence of this process on the microstructural and mechanical properties was also examined. The reference material was a 3 mm nitinol strip with a homogeneous austenitic B2 phase. For the laser surface melting process, input fluences were applied from 17.5 to 45 J/mm2. The morphology of the structure and the chemical composition of several regions were determined by optical microscopy, scanning electron microscopy, dispersive energy spectra, and X-ray diffraction techniques. The mechanical properties, such as modulus of elasticity and hardness, were determined using nanoindentation and microindentation techniques. The greatest surface finishing of the fusion zone was observed for the condition 35 J/mm2. Three well-defined regions (fusion zone (FZ), heat-affected zone (HAZ), base metal (BM)) could be observed and dimensions of grain size, width, and depth of the melted pool were directly affected by the laser fluence. The geometry of the molten pool could be controlled by the optimization of the laser parameters. High laser fluence caused preferential volatilization of nickel, dynamic precipitation of intermetallic phases, including Ti2Ni, Ni3Ti, and Ni4Ti3, as well as solubilization of TiC in the matrix, which led to grain refinement. Thus, high laser fluence is a suitable technique to enhance mechanical properties such as hardness and Young’s modulus.

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