Study On Microstructure And Properties Of WC Reinforced Iron-Matrix Composites By Arc Additive Molding

Metal matrix composite materials not only have the good toughness,plasticity and thermal conductivity of metal materials,but also have the high hardness,high strength,high temperature resistance and wear resistance of ceramic materials.The additive manufacturing of metal matrix composites is a current research hotspot.Among them,the arc additive manufacturing technology has simple process flow and low cost,generally does not require subsequent plastic processing,and is suitable for the manufacture of medium and large complex shapes of metal matrix composite parts.In this dissertation,based on the MIG arc additive,with the simultaneous gravity feeding(mixed powder of WC and Fe),bottom-up,layered and layered production of reinforced iron-based materials with different contents of WC particles Composite material formed parts,and the influence of WC content on the microstructure and mechanical properties of the formed parts was studied and analyzed.The WC particles are uniformly mixed with Fe powder in proportion and the sample is formed by arc additive accumulation.Observing the microstructure of the sample,it is found that when the mass fraction of WC is 0%and 20%,the structure of the formed part is mainly ferrite The reason is that the content of 20%WC is relatively small relative to the entire forming part.The high temperature causes serious WC burnout,resulting in the formation of the formed part is mainly ferrite.When the WC mass fraction is 40%,60%,80%and 100%,the formed parts mainly contain ferrite and tungsten-rich carbide(Fe₃W₃C).The WC particles in the formed parts are divided into two characterization forms:incomplete dissolution and complete dissolution.The completely dissolved WC particles decompose W and C atoms and diffuse into the Fe matrix to form a metallurgical bond.After solidification,tungsten-rich carbide(Fe₃W₃C)with higher hardness is formed,which improves the wear resistance of the formed part.In terms of mechanical properties,as the mass fraction of WC particles increases,the microhardness of the formed parts gradually increases,and the tensile strength and yield strength show a trend of first increasing and then decreasing.The elongation after fracture gradually decreases,and the friction coefficient and wear The amount presents a trend of first decreasing and then increasing.The microhardness of the formed parts is increased from 0%220HV_0.2to 100%979HV_0.2.When the mass fraction of WC particles is 60%,the tensile strength of the formed part reaches the maximum value of 1092MPa,which is 1.8 times higher than that of the 0%formed part.When the mass fraction of WC particles is 40%,the maximum yield strength is 871MPa.When the mass fraction of WC particles is 80%,the friction coefficient and the amount of wear are the smallest,and the wear resistance is the best.