Study On Preparation,Microstructure And Properties Of TiC_p/15Cr Hypoeutectic High Chromium Cast Iron Composite

This article is based on further improving the hardness/wear resistance of high chromium cast iron materials to obtain a high wear resistance and low cost wear resistance material to meet the demand for high performance wear resistance materials year by year.Using chromium cast iron as the matrix,a fully densified sintered nano-scale TiC_p reinforced hypoeutectic 15Cr high chromium cast iron composite material was successfully prepared.The author first systematically studied the super-solid phase sintering densification behavior of the high-chromium cast iron-based composite material when the TiC_p addition amount was changed within the range of 5-25%under the condition that the composition of the hypoeutectic 15Cr series high-chromium cast iron was determined.The influence of TiC _p and TiC_p content on the microstructure and mechanical properties of the composite material was determined to optimize the sintering process,and a high-density,high-performance composite material was prepared.Then the effects of quenching and tempering on the microstructure and properties of composite materials were studied,the importance of heat treatment to alloys of different components and the optimization process were determined,and the mechanism was analyzed.Finally,the sliding wear resistance evaluation experiment of the sintered TiC_p reinforced high chromium cast iron composite with excellent performance was carried out and compared with the TM-52 steel-bonded cemented carbide.At the same time,the composite material and TM-52 under different working conditions and TM-52 steel bonded carbide wear mechanism were analyzed and studied.The research results obtained show that:1)When the TiC_p addition amount is in the range of 5-25%,the super solid phase liquid phase technology can be used to obtain TiC _p/high chromium cast iron composite materials with a relative density of more than 97.3%,achieved the goal of composite preparation,high density/high hardness and wear resistance.2)With the increase in the amount of TiC_p added,it gradually forms a continuous network-like distribution at the grain boundaries of high-chromium cast iron,dividing the matrix of high-chromium cast iron into islands.The M₇C₃ type carbides of high chromium cast iron are mainly concentrated in the matrix island and precipitated in the form of coarse rods.3)With the increase of TiC_p addition,the hardness of the composite material gradually increases,while the density,impact toughness and flexural strength decrease.The main contribution of the TiC hard phase is to ensure the hardness of the mat erial,while the Fe matrix as the binder phase mainly ensures the strength and toughness of the material.Too many hard phases intensify the stress concentration inside the matrix and the formation of rapid micro-crack propagation,which deteriorates the s trength and toughness;while too few hard phases can not reach the original idea to further increase the hardness/wear resistance of high chromium cast iron.Therefore,the amount of hard phase added is one of the important indicators that affect the final wear resistance of composite materials.4)When the sintering temperature is 1230℃and the TiC_p addition is 20wt.%,the comprehensive mechanical properties of the hypoeutectic 15Cr high chromium cast iron composite material reach the best;its mechanical properties are:hardness66.84HRC,impact toughness 2.06J/cm²,the bending strength is 1343MPa.When the TiC_p addition amount is 25wt.%,the alloy hardness reaches the maximum value of67.20HRC.5)Quenching+tempering can further increase the hardness of the composite material,especially the quenching treatment;but with the increase of TiC _p addition,the effective effect of increasing the hardness will gradually decrease.After 960℃×1h+air cooling heat treatment,the composite material containing 20wt.%TiC_p has a hardness of 69.84HRC,an impact toughness of 1.61J/cm²,and a flexural strength of1222.94MPa.6)Under the load of 60N～150N,containing 25wt.%TiC _p has excellent sliding wear resistance.Compared with TM-52 steel-bonded cemented carbide,the wear resistance is improved by at least 30%.