Microstructure and Mechanical Properties of Two-Layer Laser-Cladded Co-Based Coatings
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Two-layer Co-based cladded coatings with high-temperature wear resistance were fabricated on the surface of Q235 steel by using laser cladding process. The microstructure and phase constitution of the cladded coatings were observed by SEM, EDS, XRD and TEM. The microhardness and high-temperature wear behaviors of the cladded coatings were evaluated by friction wear equipment. The microstructure of the upper region of the first-layer cladded coatings showed a uniformly dendrite formation, while amorphous phase existed in the upper region of the second-layer cladded coatings because of the comparatively lower dilution in the upper layer. The microhardness of the second-layer cladded coatings was up to over 1200 HV0.2 which was six times of the substrate. The wear loss of the second-layer cladded coating was 18.3% less than that of the first-layer cladded coating. The second-layer cladded coating possessed excellent comprehensive mechanical properties due to the existence of amorphous phase.
Keywordsamorphous phase Co-based cladded coatings laser cladding surface mechanical properties
This study was supported by State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, the Natural Science Foundation of Shandong Province (No. ZR2016EEQ03), China Postdoctoral Science Foundation-General Program (No. 2018M641822), the Natural Scientific Research Innovation Foundation in HIT (No. HIT.NSRIF.201703) and the National Natural Science Foundation of China (No. 51375294).