Research On The Density Improvment And Micro-defect Elimination During DLMS

Direct Laser Metal Sintering (DLMS) based on the process of Selective Laser Sintering (SLS)is used for manufacturing metal parts by scanning metal powder placed in advance.Because of the technology facts,DLMS still keeps some defects,such as low density,too many micro-defects, high remnants stress and so on,as well as good surface,high forming accuracy,non-aftertreatment,which are it's advantages.In this paper, a series of experiments are carried out with DLMS for FGH95 which is one of Nickel-based metal powder materials.The forming mechanism and effect of process parameters in sample quality was investigated and analyzed from the craft viewponit. The main works are as following:(1) The properties of metal powder and it's laser sintered mechanism are researched.The main problems and it's effecting factors in metal powder are analyzed in emphsis.(2) A series of based experiments with DLMS for FGH95 are carried out.The base with oxide laser is chosen,on which a part with good surface was gained in the best parameters of DLMS.(3) The power of laser,scanning speed,density of powder play an evident influence in the micro-structure.It is found that the micro-structure of part is mainly composed of equal-axes crystale and cylindrical crystale and the power of laser and scanning speed play a more important part in the size and proporytion of the crystale.The scanning space have important impact on micro-defects elimination.(4) The power of laser,scanning speed,density of powder do an important effect in the rigidity and density of parts. The power of laser and scanning speed do a unstable impact on the rigidity and density of parts, while the two indicators straight increases when the density of powder is higher. It is proved that a perfact part could be gained when scanning space is 0.6mm.