Research Of 316L Stainless Steel Powder Materials By Gelcasting

As a rapid prototyping additive manufacturing(AM)technology,3D printing is attracting progressive increase in researchers' attention.Still,there are numerous obstacles in its way of development.Metallic 3D printing,using metal powder as raw material,has flaws such as high equipment cost and lack of intensity of product.Powder hydrometallurgy,developed by combination of 3D printing with gel casting,is capable of achieving rapid prototyping of complex metal parts.In this article,gas atomized 316 L stainless steel is selected as raw as material.First,complex plastic shell mould produced by 3D printing was used as the container for subsequent slurry filling,reaction and solidification.Then,by researching the ratio of different monomer solvents,amount of dispersant added,as well as the ratio between initiator and catalyst,with regard to the criteria-slurry viscosity,solidification time and green strength,the optimal slurry ratio was selected.Simulation of the slurry filling process was conducted using Fluent,indicating the influence of sintering temperature and holding time on the microstructure,bending strength,tensile strength,hardness and intensity of components produced.The research outcome determines the processing technique of fast complex component production using 316 L stainless steel via 3D printing and gel casting,setting the foundation of manufacturing complex shaped,large sized metal components with low cost and high efficiency.The experiment discussed the influence of the ratio change of each component in slurry in room temperature.The results showed that the content of solid phase,the ratio of monomer solvents and the content of dispersant have major impact on the viscosity of the slurry.By researching the impact of ratio between crosslinker and catalyst on solidification time and level of reaction,it was revealed that solidification time increased with the increment of crosslinker and catalyst.However,an excessively violent reaction(lack of reaction time)would result in a decrease of intensity.Three-point bending test was conducted to study the influence of solid phase content on green strength.The results indicated that as the solid phase content increased,the green strength would first increase,then decrease accordingly.According to the viscosity data of different shear rate measured by fitting in the Carreau models of non-Newtonian fluids,precise 3D models were constructed in Fluent.Various material data such as viscosity and density were imported to conduct simulation of filling condition of slurries of different solid phase content.By testing and comparing typical simulated conditions,it was discovered that the simulations conformed well to experimental results,indicating the reliability of prediction of filling process from simulation.By conduction thermogravimetric analysis(TGA)on the solidized green,the TGDSC curve of Toluene-HEMA gel system was obtained.Holding temperature and a series of sintering temperature were determined from the thermogravimetric curve and the melting point of 316 L stainless steel.Subsequent analysis was carried out on the sintered materials.The experiment results showed that as the sintering temperature rose,the intensity and mechanical properties all improved,and the size of grain changed.Combined with microstructure and mechanical properties,it was discovered that the optimal sintering parameter of gel casting 316 L stainless steel was to hold 1.5h at 1350?.