Experimental Investigation On Direct Metal Laser Sintering Of Nickel-based Metal Powder Material

Direct Metal Laser Sintering is an important branch of Selective Laser Sintering technology.It improves the production flexibility because of needing no any dies and tools,being unrestricted by geometry shape of part, and higher material utilization,shorter production cycle and so on.It is becoming an important development direction of advanced technique of manufacture.Due to the limitation of material properties and processing conditions, lots of flaws exist in the parts processed by DMLS.The choice of processing parameters determine on the formation and micro-structure and performance of metal part.Therefore,to obtain fine sintered part with regular shape,high densification and fine performance,the relationship between processing parameters and quality of parts was needed to acquire.In this article,a series of experiments were carried out with DMLS for Nickel-based metal powder material.The effect of DMLS and process parameters on the quality of samples was also studied and analyzed.The main works are as follows:(1) Studying the interaction mechanism between laser and the material, and analyzing the dynamic process of rapidly solidification of molten pool.(2) Through a series of the sintering experiments of nickel-based metal powder material,it is clear that which process parameters affects the quality of sintering parts and how they affect.The research indicated that the laser power and scanning speed had an obvious influence to the microstructure, micro-hardness and bulk density of samples.As the increasing of power,the microstructure will become large.Meanwhile,it can improve the micro-hardness and the bulk density of samples.And the higher scanning speed has a significant effect on microstructure refinement,and can enhance the micro-hardness of samples obviously.The best parameters for material of Nickel-based alloy powder F105Fe are:P=1000W,V=1200mm/min,S= 0.45mm,δ=0.3mm,D=0.9mm.(3) Some metal parts with required-shape and certain mechanical strength have been produced successfully by sintering on Nickel-based metal powder with powerful laser.(4) There are many flaws in Direct Metal Laser Sintering process,such as the micro-hole and micro-crack and high residual stress in parts.In order to solve those problems,the programming of scanning paths has been put forward,and several parts are sintered with different scanning paths respectively.The following conclusions are educed:the parts which sintered with short-side scanning path and the same scanning direction have the finest micro-structure,the micro-hardness of parts sintered with short-side and same direction scanning path is highest,the bulk density of part which sintered with vertical scanning path is supreme.