超高速激光熔覆与常规激光熔覆431不锈钢涂层微观组织和耐蚀性的对比

Herein, a tempered 27SiMn hydraulic support substrate with 431 stainless steel corrosion-resistant coatings is successfully prepared by 50 m/min extreme high-speed laser cladding (EHLA) and 1.5 m/min conventional laser cladding (CLA) methods, respectively. The macroscopic features, microstructure, and corrosion resistance of the coatings prepared by both methods are comparatively investigated. Results show that the coatings prepared by both methods form good metallurgical bonds without microcracks and blowhole defects. Compared to the CLA coating, the EHLA coating has a multi-layer structure similar to the "dominoes" and a low dilution of 4%. Cr achieves a high atomic number fraction of 19% in the EHLA coating. The macroscopic structure of the CLA coating is relatively large, and the direction of dendrite growth is disordered due to the change of temperature gradient at the overlapping zone. The macroscopic structure of the EHLA coating has a high degree of uniformity and compactness, and the microstructure at the bottom/substrate interface is planar crystalline. The dendrites in the middle overlapping zone and the surface of the EHLA coating are finer and slightly roughened at the overlapping area. The corrosion resistance of the EHLA coating is significantly superior.