Research Of Technology And Properties Of Laser Cladding On Ni/al₂ O₃-la₂o₃ Surface Of 38crmoal Steel

Laser cladding technology is a surface modification technology that developes rapidly in recent years, which is done by adding the substrate surface cladding materials and take advantage of high-energy density laser beam to make it melt with the substrate surface, to form a good metallurgical bonding of the cladding layers in the substrate so as to improve or repair components and extend their useful life.Based on 38CrMoAl steel for research object, this paper conducted research on the technics of laser cladding Ni-based alloy on the 38CrMoAl steel surface and microstructure, combinationproperty, crack control, overlapped region of cladding layers, and studied the situation of cladding layers performance after mixing Al₂O₃ hard phase, rare earth oxide La₂O₃ and Mo into Ni base alloy. Through the comparison analyses of the macroscopic and microscopic qualities for cladding layers, the laser cladding parameters were perfect. Microstructure of cladding layers was characterized using scanning electronic microscope. The microhardness of cladding layers was measured using HXD-1000 type micro-sclerometer. Friction and wear performance of caldding layers were examined using an M-2000 type pin-on-disk friction wear tester.The analysis of cladding layers shows: the microhardness values of cladding layers increased prominently than the substrate, but hardness is not very well-distributed, which reached the peak hardness in the sub-surface of the cladding layers; Strengthening mechanism of cladding layers mainly include refined crystaline strengthening, solid solution strengthening, hard phase strengthening and so on; Microstructure of cladding layers is prominently refined compared with the substrate. Due to the multi-strengthening mechanism, the hardness and strengths of cladding layers are increased remarkably, and thus leading to an extremely high wearability.The hardness of cladding layers is changed little but the wearability is greatly improved and the sensitivity to crack is increased after adding hard phase Al₂O₃; The sensitivity to crack of cladding layers is reduced and the hardness is decreased slightly but the wearability is not reduced after adding Mo; Crystal grain can be refined and the hardness, the wearability are improved greatly and the cracks are reduced significantly after adding rare earth oxides La₂O₃.