| The studies of plasma beam as one of three high-energy beams cladding on steel surface are significant since it developed little. At present laser cladding becomes one of many hot surface treated technologies, but it is scarce for the studies of Fe-based alloy. So it is frontier for plasma beam cladding Fe-based alloy. Author lastly attained fine microstructure and property through four phases' exploration.According to the principle of metallurgy and metallography, the crystallizing process is discussed theoretically from thermodynamics to dynamics to segregated spot to ingredient over-cooling. Further the rules of crystallized procedure of plasma beam cladding are generalized.In response to the above crystallizing rules, the crystallizing mechanics of plasma beam cladding alloy layer for the fourth phase was systematically studied. Cladding layer was consisted of four crystal states, firstly mixed crystal including cellular and dendrites and equiaxed grain in the bottom, then criss-cross dendrites in the mediate, further equiaxed grain in the mediate-upper, lastly fine dendrites and equiaxed crystal in the upper. Each part was analyzed by crystallizing rules, especially white bright band.The hardness was measured from coating to substrate. It is easy to see that the value of the hardness was the highest on the coating layer, which of the substrate was the lowest.The gas cavities and cracks was emerged during the crystallizing procedure for the first phase, which forming reason was discussed, and many measures were provided to put an end to it.HAZ (heat-affected zone) was also studied. HAZ is consisted of fusion area, overheated zone, normalized zone, incompletely normalized zone and substrate. The zones are different from different substrates, which microstructure and performance are studied therein.At last, the effect of processing parameters of plasma beam cladding such as plasma power, scanning speed, multi-layer and chemical component on microstructure and property of cladding layer was investigated.Study on crystallizing procedure and HAZ of plasma beam cladding will inject new vitality for plasma beam cladding technique. And it will also open up wide application prospects for the surface reinforcement technology. |
