Research on the Thermal Fatigue Mechanism of Laser Cladding IN625 Process on Ductile Iron

• Published in: International journal of metalcasting 2024-10, Vol.18 (4), p.3129-3151
• Main Authors: Li, Chang, Zhang, Mingyang, Sun, Yichang, Han, Xing
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Materials Science; Metallic Materials; Structural Materials; Technical Paper
• ISSN: 1939-5981; 2163-3193
• DOI: 10.1007/s40962-023-01237-w

The laser cladding technology has the advantages of a low dilution rate, green environmental protection, and a small heat-affected zone of the substrate. The laser cladding forming process on the surface of ductile iron needs to be realized by multi-track and multi-layer overlapping, which will produce repeated thermal cycle accumulation and lead to thermal fatigue, and it is of great significance to quantitatively reveal the thermal fatigue damage mechanism of the laser cladding process. In this study, a numerical model of the EN-GJS-600-3 single-track laser cladding IN625 process on ductile iron was established, revealing the multifield coupling transient evolution process during the laser cladding. A multitrack overlapping laser cladding model with different overlap ratios was established to investigate the influence of multitrack overlapping on the temperature, flow rate, stress, and fatigue of the laser cladding process. Calculations show that the temperature and stress of the molten pool gradually stabilize at 1860 °C and 351 MPa after 1 s of single-track cladding. The maximum temperatures are 2030 and 2050 °C, the maximum flow rate is 0.27 m/s, and the maximum stress is 335 MPa and 358 MPa during 1 s of cladding at 30 and 60% overlap ratios, respectively. These are caused by the cumulative effect of thermal cycling in laser cladding. Thermal damage is more diffuse at a 30 percent overlap ratio and more concentrated at a 60% overlap ratio. Finally, it is found that the morphology of the numerically calculated cladding layer agrees well with the experimental result, which verifies the validity of the model.