Microstructure And Properties Of Laser Rapid Prototyping Fe-Based Alloy

Laser rapid prototyping technology has developed rapidly in recent years.As a major technological revolution in the manufacturing industry,it has been widely used in new product design,medical equipment,aerospace and other fields.It is the perfect combination of traditional manufacturing technology and new material manufacturing technology.The research of laser rapid prototyping technology provides the possibility of developing the new materials which has excellent performance and has difficulty in mass production.In this paper,Fe42.87Cr15.98M016.33C15.94B8.88 alloy samples were prepared by laser rapid prototyping technology.The effects of laser processing parameters on the microstructure and properties of laser rapid prototyping Fe-based alloys were studied.The results showed that the microstructures were bright and dark.In the layered structure,the clad zone is a black crystal cell precipitated phase and a petal crystal equiaxed crystal phase,and the heat affected zone is a gray precipitated phase and a white banded crystal precipitated phase.On the condition that the laser power is 800 W,the three sets of rapid prototyping samples are slightly better than those of the three sets of samples that under the condition of 1000 W in the macroscopic morphology,hardness,and compressive strength.With the increase of the scanning speed at 800 W,the hardness and compressive strength of the sample gradually decreased;When the laser power is 1000 W,the corrosion resistance of the sample is better.Although the hardness and compressive strength are slightly lower,with the increasing of scanning speed,the hardness and compressive strength increase gradually,the change rule under this circumstances is opposite to the former case.After studied the effect of powder particle size on the microstructure and properties of laser rapid prototyping Fe-based alloy.It was found that the Fe-based alloy which rapidly formed by Fe-based alloy powder with a powder particle size of 37?m had macroscopic holes on the macroscopic surface,only under certain circumstances,when the laser power is at 800 W,and the scanning speed is 2400 mm/min,that the nice surface of the Fe-based alloy sample could be prepared,but the micro-hardness and compressive strength were also significantly worse than those of the Fe-based alloy samples prepared under the same laser process parameters.However,the structure still appears as a layered structure between light and dark,and the clad zone is a black crystal cell precipitated phase and a petal crystal equiaxed crystal phase,and the heat affected zone is a gray precipitated phase and a white banded crystal precipitated phase.After studied the effect of adding different proportions of Ni powder on the microstructure and properties of laser rapid prototyping Fe-based alloy,it was found that the addition of 15%Ni can effectively control the crack hole defects caused by thermal stress during laser rapid prototyping of Fe-based alloy.Ni element can promote the formation of austenite and increase the amount of austenite,while the austenite structure is more plastic,therefore,as the proportion of Ni powder increases,not only the generation of crack holes but also the compressive strength is gradually improved.At the same time,compared with the Fe-based alloy without Ni powder,the hardness and compressive strength of the sample decreased,and there was no significant difference in the structure.It still appeared as a layered structure between light and dark,and the blackened cell phase and the petals were in the cladding area.The crystal is equiaxed crystallized,and the heat-affected zone is a gray precipitated phase and a white strip-shaped crystal precipitated phase.