108 / 2021-07-16 11:32:52

Defect formation mechanism of high-speed laser cladding nickel base alloy

High speed laser cladding, low alloy steel, Nickel base alloy, wear resistance, corrosion resistance

Q245 steel is expected as engineering materials for the potential application in boiler water wall tube, superheater tube, reheater tube and economizer tube, owing to its high strength, good welding performance, and excellent processing formation performance. Well-known surface modification techniques, such as thermal spraying and overlaying welding technology have been used for enhancing its surface properties before they can be effectively applied in practice at harsh service environment. However, there exist issues associated with the use of these surface modification techniques, involving unfriend environment, multi-step process, changed bulk texture, or unfavorable surface profile, etc, fail to used in long-term service. Hence, an enhanced and effective method should emerge as a highly attractive choice for surface modfication of Q245R steel without the change of its bulk properties. In this thesis, high-speed laser cladding proved to be an innovative and useful technique for preparing Ni-based alloy cladding with low porosity, high hardness, good wear resistance and corrosion resistance on the Q245R steel. The main conclusions and innovations are listed as follows: 1）Control the microstructure and performance of Ni-based alloy cladding by optimizing the parameters of high-speed laser cladding process; 2）The fracture mechanism of Ni-based alloy cladding layer was revealed by studying its microstructure morphology and phase transformation in different parameters of high-speed laser cladding process by using XRD, XPS, SEM, and TEM. 3）The comprehensive properties of Ni-based alloy laser cladding layer are studied through electrochemical detection, hardness, friction and wear test.