| High chromium cast iron is widely used as a wear material because of its certain wear resistance and low cost,however,as the requirements for material performance become higher and higher,it is urgent to further improve the wear resistance of high chromium cast iron.In this paper,the in-situ reaction of powder metallurgy is used to generate Ti&W carbides to improve the wear resistance of high chromium cast iron castings,the preparation process of preforms is studied,and the microstructure of in situ generated Ti C,WC,(Ti,W)C particles in high chromium cast iron is investigated Medium distribution and the mechanism of Ti & W carbides on the wear resistance of high chromium cast iron composites.Before pouring,a 5.7×10×20cm honeycomb Ti&W-Fe-C preform was prepared by powder metallurgy.The study is the effect of powder process parameters on the strength of the preform.The preparation process of the ball milling is the ball-to-material ratio of 8: 1,a speed of 250 r / min,and a ball mill of 2h.The preform was pressured by 100 MPa.Sintering temperature is 1100℃.After pressing and sintering,The preform can withstand the impact of 64 MPa.Then,the Ti&W-Fe-C preform is fixed at a specific position for pouring.Combined with thermodynamic calculation and experimental analysis,it can be seen that the preform will undergo high temperature self-propagation reaction during the casting process to generate Ti C,WC,(Ti,W)C and other carbide particles.Microstructure analysis found that the average particle size of Ti C,WC,(Ti,W)C particles prepared by in-situ synthesis method is less than 5μm,and a small amount of carbide particles are agglomerated;the matrix structure is primary crystal carbide and ferrite Body and eutectic carbides.The hardness results of Ti&W carbide-reinforced high-chromium cast iron composites show that the hardness of carbide particles such as Ti C,WC,(Ti,W)C is higher,and the average hardness reaches 55.2HV,57.5HV and 65 HV,respectively.Then,the average hardness of the three Ti & W carbide reinforced high chromium cast iron composite materials is different.In the Ti C reinforced high chromium cast iron,the average hardness of the high chromium cast iron distributed in the preform Ti C is 28 HV,while the average hardness of the base medium high chromium cast iron is 18.5HV;in the WC reinforced high chromium cast iron,the high distribution in the preform WC The average hardness of chromium cast iron is 35.1HV,and the average hardness of medium and high chromium cast iron is 24.1HV;in(Ti,W)C reinforced high chromium cast iron,the average hardness of high chromium cast iron distributed in the preform Ti C is 28.8HV,and the base The average hardness of medium and high chromium cast iron is 18.9HV.Finally,the wear resistance of composite materials and high-chromium cast iron is analyzed and found that the three-body wear properties of the three composite materials are higher than that of chromium cast iron by more than 1.2 times.The improvement of the abrasion performance of composite materials is mainly due to the protection and support of Ti C,WC,(Ti,W)C particles generated in situ on the matrix.High-chromium cast iron mainly wears abrasive particles,and the wearer mainly uses micro-cutting and micro-flaking mechanisms.The composite material mainly wears abrasive wear-adhesive wear.The surface of the composite material will undergo repeated plastic deformation,work hardening,brittle fracture and even fatigue fracture under the repeated rolling of the abrasive particles.Protruding carbide particles can easily form a bite with abrasive debris and cause adhesive wear. |
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