Study On Microstructure And Wear Behavior Of Series Of Engineering Machinery Steel

In recent years,low-alloy wear-resistant steel has been rapid development,China has basically production capacity of a full range of low-alloy wear-resistant steel,but still optimization on the wear-resistant steel composition and production process,improving performance,to expand its application areas,and gradually replace the traditional wear-resistant materials and some high-strength structural steel.At present,the domestic production of low-alloy wear-resistant steel using quenched and tempered technology,it's large energy loss,high cost and long production cycle.In this paper,we study the organization,mechanical properties and wear properties of NM400 of the on-line process and off-line process to provide a theoretical basis for the online production of NM400.The wear resistance and wear mechanism of the series of high strength steel and series wear resistant steel are compared,which provide data reference for low alloy wear resistant steel instead of high strength structural steel under certain working conditions.The main findings are as follows:(1)The NM400 Vickers hardness under the two processes of on-line and off-line is more than 430HV,and the crystal of NM400 produced by the online process is flattened,and the slats in the martensite slab long and thin,roughly parallel arrangement,part of the original austenite grain contains 2-3 different orientation of the martensite,martensite plate between the distribution of a large number of fine rod carbide.The tensile strength of the on-line process steel is nearly 100MPa higher than that of the off-line process.The yield strength is basically the same.The impact strength of the on-line process is higher than 2J.(2)With Q345 as the comparison standard,the two kinds of process steel show excellent wear performance,and the wear resistance of the on-line process steel under the agitation wear is obviously higher than that of the off-line process,which is about 1.189 times.Both of the wear mechanism are pear ditch with plastic deformation caused by fatigue peeling.(3)The study of the wear behavior of different microstructures shows that the relative wear resistance and hardness curve show an increasing trend with three different slopes with the organization as the boundary.When the hardness is 150HV-200HV,the microstructure is pearlite/ferrite.The ascendant slope of the relative wear resistance of the experimental steel is the most gentle when the hardness is more than 200HV,the microstructure becomes ferrite/granular bainite,and the slope of relative wear resistance of the experimental steel increases.When it's martensite region,the slope of the relative wear resistance increases with the hardness is the max,and the slope of the microstructure structure and relative wear resistance are as follows:martensite>bainite>pearlite/ferrite.(4)The effect of hardness on the wear properties of the material shows that the abrasion behavior of martensite wear-resistant steel is significant pear when the hardness is about 400HV,and the plastic deformation fatigue is decreasing.Hardness of 450 or more,the wear surface of the plastic deformation of the material significantly is less,while the shallow pear traces occupy the entire wear surface.From the relative wear resistance and hardness of the curve found that wear-resistant steel martensite structure is a certain slope rise,which also verified the martensite hardness and relative wear resistance of the law of the rise in the fourth chapter,And in comparison with the high-strength steel also found that the same hardness conditions,different chemical composition of the martensitic structure of the changes in the trend there are some differences.