Effect of a small addition of Ti on the Fe-based coating by laser cladding

In this study, the coatings were fabricated on a low carbon steel substrate by laser cladding using the Fe-based powders mixed with different Ti content. The effects of the Ti and its content on the microstructure, phase compositions and microhardness of the clad layers are studied systematically. The results show that, the addition of Ti into Fe-based alloy powder changes the morphology and microstructure of the coatings obviously. The equiaxed grains or dendritics appear instead of dendrite structures, and the microstructure becomes refined and uniform. In addition, with the increase of Ti content, the dilution rate of the coatings goes up and the size of crystal phase in the deposits becomes larger, which makes the hardness of high-doped layers decrease sharply. Meanwhile, the reasons for these differences are analyzed in detail. At last, by comparison, the Fe-based mixed with 1 wt.% Ti coating has the most desired performance. It has high hardness which is not sensitive to the scanning speed under the condition that the ratio of the powder feed rate to the scanning rate is constant. And the hardness distribution through the clad layers is much stable.