Mechanism of heat affected zone cracking in Ni-based superalloy DZ125L fabricated by laser 3D printing technique
| Autor: | Kai Chen, Yao Li, Nobumichi Tamura |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Cladding (metalworking)
Heat-affected zone Materials science 02 engineering and technology Manufacturing Engineering 01 natural sciences Carbide Stress (mechanics) 0103 physical sciences lcsh:TA401-492 General Materials Science Composite material Laser 3D printing Materials Eutectic system 010302 applied physics Mechanical Engineering Residual strain/stress Materials Engineering Intergranular corrosion 021001 nanoscience & nanotechnology Superalloy HAZ cracking Cracking Mechanics of Materials Ni-based superalloy Synchrotron X-ray microdiffraction lcsh:Materials of engineering and construction. Mechanics of materials 0210 nano-technology |
| Zdroj: | Li, Y; Chen, K; & Tamura, N. (2018). Mechanism of heat affected zone cracking in Ni-based superalloy DZ125L fabricated by laser 3D printing technique. Materials and Design, 150, 171-181. doi: 10.1016/j.matdes.2018.04.032. Lawrence Berkeley National Laboratory: Retrieved from: http://www.escholarship.org/uc/item/7gv5g5f6 Materials & Design, Vol 150, Iss, Pp 171-181 (2018) |
| DOI: | 10.1016/j.matdes.2018.04.032. |
| Popis: | Laser 3D printing is a promising technique to repair damaged Ni-based superalloy components. However, the occurrence of heat affected zone (HAZ) cracking severely limits its applicability. Here we unravel the cracking mechanism by studying the element, phase, defect, and strain distribution around an intergranular crack that initiated from the primary HAZ. Using synchrotron X-ray Laue microdiffraction, we measured high tensile strain/stress transverse to the building direction in both the primary HAZ and the cladding layers, as well as high-density dislocations, which resulted from the thermal contraction and rapid precipitation of γ′ phase. The crack initiated because the transverse tensile strain/stress tore up the liquid film formed by the low-melting point preexisting phases in the primary HAZ, such as γ/γ′ eutectics and coarse γ′ precipitates. The incoherent carbide particles were frequently observed near the crack root as local strain concentrators. In the cladding layers, micro-segregation could not be completely avoided, thus the hot crack continued to propagate over several layers with the assistance of the transverse tensile stress. Our investigations provide a useful guideline for the optimization of the 3D printing process to repair Ni-based superalloys with high susceptibility to hot cracking. Keywords: HAZ cracking, Laser 3D printing, Ni-based superalloy, Residual strain/stress, Synchrotron X-ray microdiffraction |
| Databáze: | OpenAIRE |
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