Microstructure and wear resistance property of laser cladded CrCoNi coatings assisted by ultrasonic impact treatment

Abstract

In this paper, CrCoNi medium-entropy alloy coatings were prepared by laser cladding process, and ultrasonic impact treatment (UIT) with different impact amplitudes (0 μm, 10 μm, 15 μm, 20 μm) was performed on the coating surface to systematically study the microstructure and properties of the coatings. The results showed that the surface deformation of the coatings became more and more severe with the increase of ultrasonic impact amplitude. After the UIT treatment, the impact layer with obvious plastic deformation appeared on the top of the coating, and the depth of the impact layer gradually increased with the increase of the amplitude, and the influence range of the impact layer could be roughly judged according to the increase of the small-angle grain boundary on the top, which was about 200–400 μm at the amplitude of 20 μm. The grain size was 64.067 μm at an amplitude of 20 μm, which was about 34% of the original size. The microhardness of the coating was found to increase with the impact amplitude, and when the impact amplitude reached 20 μm, the microhardness of the coating reached 374.1 HV0.2, which was 122% higher than that of the unimpacted coating. Also, the wear resistance of the Cr–Co–Ni coating increased with the increase of impact amplitude, and the wear weight loss of the coating increased by 85.71% compared to the untreated specimen at an impact amplitude of 20 μm.

Keywords

• Laser cladding
• Ultrasonic impact treatment
• CrCoNi
• Wear resistance