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The laser cladding of self-fluxing Fe–Cr–Ni alloys on a medium carbon steel substrate was performed using a CO 2 laser and Ar shielding gas that was blown into a molten pool. The cracking susceptibility and microstructure of the laser-clad layer were studied in terms of Co additions. Co can change the microstructure of a Fe–Cr–Ni alloy clad layer from eutectic to hypoeutectic and decrease the cracking susceptibility of clad layers. However, these results relate not only to the Co content in the laser-clad alloys, but also the number of overlapping tracks. With the increment of Co content in clad layer, the cracking susceptibility of the laser cladding layer decreases and the number of overlapping tracks with hypoeutectic structure increases. At the same time, Co does not change the hardness of the clad layer.

An investigation is reported of the laser surface cladding of self-fluxing Fe–Cr–Ni alloys on a medium carbon steel substrate using the preplaced powders method with gas shielding or vacuum protection. The cracking susceptibility and microstructure of the laser-clad layer have been studied in terms of Hf additions. Hf can change the microstructure of the Fe–Cr–Ni alloy clad layer from eutectic to hypoeutectic. The lowest cracking susceptibility occurs when the Hf content in the laser-clad layer is approximately 0.9% wt. But to achieve this effect there must be 3.0% wt. Hf in the alloy powders when shielding with gas. The effect of the protecting condition on cracking susceptibility of the laser-cladding layer is also reported

A graded coating consisting of an Ni-clad Al bond layer, a 50wt.% Ni-clad Al + 50wt.% (Al 2 O 3 -13wt.%TiO 2 )intermediate layer and an Al 2 O 3 -13wt.%TiO 2 over-layer (or ceramic layer), was produced on an Al-Si alloy substrate by plasma spraying and then was remelted by laser-beam irradiating. The thermal-shock resistance of the plasma-sprayed coating and the laser-remelted coating was investigated in this study. The plasma-sprayed coatings show a lot of spallation at the different depths of coatings and a few macrocracks in the ceramic layer during thermal cycling, but the laser-remelted coatings show a great amount of network microcracks in the ceramic layer and only a little spallation at the interface between the intermediate layer and the bond layer. Thus the laser remelting treatment improved the spalling resistance of plasma-sprayed coating to thermal shock, but cracking resistance to thermal shock remains a problem to be solved by further investigation.

An investigation is reported of the laser surface cladding of self-fluxing Fe–Cr–Ni–B––Si alloys on a medium carbon steel substrate using the preplaced powder method. The cracking susceptibility of the laser-clad layer has been studied in terms of the melting properties of the cladded alloy. The smaller the fusion temperature zone and fusion-end temperature of the cladded alloy, the lower the cracking susceptibility of the laser-clad layer. The effect of the latent heat of fusion of the cladded alloy on cracking susceptibility is not apparent.