Study On Abrasive Wear Behavior Of Fe-C-Mo-V Hardfacing Alloy

In recent years,most of the welding consumables use to repair industrial components by welding is Fe-Cr-C welding alloy due to its good mechicanical property price ratio.Fe-C-Mo-V hardfacing alloy is a new type of iron-based hardfacing alloys with high-vanadium and high-molybdenum.It has excellent wear resistance and performs well in the market.However,there are few reports on the wear behavior and mechanism of the said alloy,the study on this has guiding significance for practical applications.In this paper,the new Fe-C-Mo-V hardfacing alloy was carried out on the dynamic load impact wear test,the ring block three-body wear test and the dry sand rubber wheel wear test.The wear behavior and mechanism of Fe-C-Mo-V hardfacing alloy in the abrasive wear environment was systematically studied by using the experimental methods such as chemical composition detection,optical phase analysis,microstructure and performance testing.Moreover,the differences of the wear resistance and resistance mechanism of Fe-C-Mo-V hardfacing alloy with Fe-C-Cr-Nb hardfacing alloy under the same working conditions were analyzed.The results showed that the microstructures of Fe-C-Mo-V hardfacing alloy is mainly composed of alloying austenite matrix,lamellar alloy carbides(M2C and M3 C,M=Fe,Mo,Mn),VC hard phase,a small amount of ferrite and martensite/austenite structure(M-A structure)was also found.The major microstructures of Fe-C-Cr-Nb hardfacing alloy included austenitic dendritic matrix,network eutectic,Nb C hard phase and a slight amount of M23C6 and M3 C.Compared with Fe-C-Cr-Nb hardfacing alloy,Fe-C-Mo-V hardfacing alloy had a larger volume percentage of carbides and the VC hard phase was approximately spherical.In addition,the morphology of eutectic carbide was flake rather than network.There were microcracks at the interface between austenite matrix and eutectic carbide observed in Fe-C-Mo-V hardfacing alloy and Fe-C-Cr-Nb hardfacing alloy.The results of the dynamic load impact wear test showed that when the impact energy was in the range of 1J to 7J,the wear loss of Fe-C-Mo-V hardfacing alloy decreased significantly with the increase of impact energy under the environment of impacting abrasives,and when the impact energy exceeded 5J,the change of wear loss weight was very small.The results of the ring block three-body wear test displayed that under the environment of sliding abrasives,when the load was 10 N with the increase of speed,the volume wear rate of Fe-C-Mo-V hardfacing alloy decreased first and then gradually increased if the speed was more than 30r/min.When the load was more than10 N,the volume wear rate of Fe-C-Mo-V hardfacing alloy decreased with the increase of speed.The dry sand rubber wheel wear test results discovered that under the environment of rolling abrasives,the wear loss and the volume wear rate of Fe-C-Mo-V hardfacing alloy gradually decreased with the increase of the rotation speed at the same wear mileage and load.The analysis of the macro morphology,wear scar subsurface microstructure and hardness test of the worn sample showed that the degree of wear was mainly related to the austenite matrix transformed into martensite,the VC hard phase and lamellar alloy carbides were broken and spalled,and the degree of work-hardening of the wear subsurface.Under the conditions of impact abrasive wear,sliding abrasive wear and rolling abrasive wear,it was shown that under the same other conditions,at low load or low speed,austenite matrix was cut and ploughed by the quartz sand abrasive,carbides both VC and lamellar alloy were broken and spalled,and the subsurface of wear scars had low degree of work-hardening.At high load or high speed,the austenite matrix transformed into martensite,the degree of wear of the abrasive on the matrix was weakened,and the volume wear rate decreased.Under the condition of sliding or rolling abrasive wear,the most serious wear was the grinding region.The wear mechanism of Fe-C-Mo-V hardfacing alloy under abrasive wear conditions was as follows: when the load or speed was low,the degree of surface work-hardening was small,and the abrasive was not greatly broken.At the same time,due to the presence of microcracks around the carbides in the deposited metal,there was an interaction between the abrasive and the microcra cks.Because of the little compression force,the abrasive will be partially embedded in the microcracks,increasing the microcrack gap or spalling off the carbides directly to leave spalling pits.Under the action of cyclic load with squeezing or sliding,the quartz sand abrasive would be squeezed into the spalling pit and embedded in the matrix,causing heavier wear.When the load or rotation speed was high,the degree of surface work-hardening was higher,the abrasive was gradually broken to a large extent,and the squeezing and cutting action of the abrasive dropped.At the same time,due to the synergistic protective effect of VC hard phase and lamellar alloy carbides,the material wear loss and the volume wear rate was reduced.By contrast,Fe-C-Cr-Nb hardfacing alloy was suitable for use in high impact energy,high load,high speed or high load with high speed abrasive wear conditions.Under low or medium impact energy or speed abrasive wear conditions,the wear resistance of Fe-C-Mo-V hardfacing alloy was significantly higher than the former.Under high impact energy,high load,high speed or high load with high speed abrasive wear conditions,the wear resistance of Fe-C-Mo-V hardfacing alloy was better than the former.And Fe-C-Mo-V hardfacing alloy had a wider range of applications than the former.