Microstructures And Compressibility Of Porous Stainless Steel Prepared By Laser Sintering

Laser Sintering (LS) is an important branch of Rapid prototyping (RP). Compared to conventional powder sintering technology, it has many advantages such as short production cycle, net shaping and so on. Therefore, laser sintering technology is especially fit for fabricating single precise porous metal component. However, this technology is currently on the starting stage, and there are many researches needed to be carried out in the future, for example the basic forming mechanisms of porous structure during laser sintering, and the relationship between the laser parameters and the property of porous metals, and so on. In this paper, the effect of laser parameters on the microstructure of porous stainless steel during laser sintering was studied, and the compression behavior of porous stainless steel prepared by laser sintering was analyzed by static compression experiment.Serial experiments of preparing porous stainless steel by laser sintering of pure 316L stainless steel powder were carried out, and the effect of laser parameters on the porous structure and compression strength of porous samples was studied. The result shows that the porosity characteristics of porous samples have intimate relationship with the laser parameters except the average aperture. Using a scan speed of 0.05 m/s and a laser power of 400W, a porous stainless steel sample with uniform pores distribution and high compression strength can be fabricated.By laser sintering of the mixture powder contained 316L stainless steel, H3BO3 and KBF4, a serial experiment of fabricating porous samples was carried out. The effect of laser parameters on the porous structure of samples prepared by laser sintering was analyzed. The results show that with increasing the value of scan speed or decreasing the value of laser power, the porosity of samples becomes higher, and the distribution width of aperture becomes larger, and the connectivity of pores in the laser sintering samples become poor. Using a scan speed of 0.03 m/s and a laser power of 600W, a porous stainless steel sample with a regular lotus-type porous structure can be fabricated.By laser sintering the mixture powder contained 316L stainless steel, H3BO3, KBF4, and MgCO3, the experiment of fabricating porous stainless steel sample was carried out. The microstructure and the compressibility of the porous stainless steel were studied. The results show that circle pores and random geometry pores exist in the samples. In the microstructure of the compressed sample, a large number of deformation bands and micro cracks at the sharp corner of the random geometry pores can be observed. The compression deformation process of the sample is consisted of four stages such as elastic distortion, partially plastic deformation, perfectly plastic deformation and fracturing.