Erosion Wear Properties Of High Chromium Cast Iron In Asphalt Concrete

As excellent wear resistant material,high chromium cast iron is used in concrete mixer lining,blade and other parts.At present researchers have done a lot of research about its wear resistance,and most researchers put mixture of water and sand,mud,solution of acid and alkali as the erosion wear medium.The asphalt concrete as the study of wear medium directly has rarely been reported.Different chromium and vanadium content of high chromium cast iron were prepared by alloy composition design.Microstructure,phase composition,hardness and impact toughness are achieved by Optical microscope,X-ray diffraction,Rockwell hardness tester,Impact toughness tester respectively.The erosion wear behavior of high chromium cast iron is studied by homemade tank erosion wear testing machine.The wear surface of samples were observed and analyzed by SEM and EDS,and the wear mechanism was also discussed.The main conclusions of this paper are presented as follows.?1?As cast microstructure of high chromium cast iron is mainly austenite and M₇C₃carbides.After heat treatment,the microstructure of high chromium cast iron is martensite,M₇C₃carbides and residual austenite.The primary carbide with outflanking growth and Cr content increased from 15%to 27%,the percentage of carbides increased from 26.74%to34.73%.?2?The content of Cr in high chromium cast iron is 15%,20%and 27%.With the increase of the chromium content,the hardness and impact toughness increased both as-cast and heat treatment When the V content is 0.5%,1.0%,and 2.0%,as-cast and heat treatment state hardness first increased and then decreased slightly,the impact toughness was increased and then decreased.?3?With the increase of Cr content,the relative wear resistance of high chromium cast iron increased.When the Cr content is 27%,the relative wear resistance is the highest and up to14.07.The wear resistance increased and then decreased with the increase of V content and when the V content is 1.0%the relative wear resistance reached 15.38.The element of V can make the microstructure refinement and form V₂C,which can effectively improve the erosion wear properties of high chromium cast iron in asphalt concrete.?4?The relative wear resistance of high chromium cast iron increased firstly and then decreased with the increase of particle size of 2mm,5mm,and 10mm.When abrasive particle diameter is 2mm wear mechanism was mainly micro ploughing and spalling.The mechanism was mainly spalling when the particle size is 5mm.When the abrasive particle size increasing to 10mm,wear mechanism was large flaking.?5?The relative wear resistance of high chromium cast iron decreased with the increase of temperature at 140?,160?,and 180?.At the low temperature of 140?and 160?,the sample surface was not oxidized.The surface of samples was accomplished by certain degree of oxidation at 180?.At the same time,with the increase of temperature,ultimate strength of high chromium cast iron was decreased and the energy dissipations would decrease when lost equal quality for the materials.It would lead to a more serious wear phenomenon for the same energy of particles at higher temperature.On the other hand,asphalt liquidity was enhanced when temperature rise and the protection to sample surface weakened,which made the wear resistance was reduced further.When the temperature is 140?and 160?,wear mechanism is mainly a little ploughing and peeling.The wear mechanism is oxidation besides peeling and ploughing.