Effect Of Mn On Microstructure And Wear Properties Of ADI

ADI(Austempered Ductile Iron),namely isothermal quenching nodular cast Iron which has become one of the most hot material,because it has excellent mechanical properties and wear resistance.The material is high-performance casting alloy,which is nodular cast iron obtained by austempering treatment,and it was consisted of carbon-rich austenite and acicular ferrite.The Mn content has three groups in the topic,the isothermal quenching process parameters have four groups,through the study of the microstructure of different sample analysis,X-ray diffraction analysis,scanning electron microscope analysis,friction and wear test,the surface hardness measurement,wear morphology observation and energy spectrum analysis,studies the Mn and isothermal quenching temperature on microstructure and wear properties of ADI.The cast of ADI which include: graphite ball,pearlite,carbide and extremely small amount of ferrite,Mn mainly exists in the form of carbides.Mn which impacts on the graphite spheroidizing effect is not obvious,but it can make the spheroidization rate to 6.Mn can influence the number of graphite ball in as-cast organization and the volume fraction of pearlite,carbide,Mn is more,graphite ball number is less,the content of pearlite and carbide are more.The matrix organization of ADI was mainly composed of acicular ferrite and carbon-rich austenite.With the increase of Mn,the original acicular ferrite gradually coarsening,rise in the Numbers.The content of retained austenite and the carbon content in austenite are more with the increase of Mn,which makes ADI work hardening under the stress,surface hardness becomes higher with the increase of Mn,which improve the wear resistance of materials.The study of isothermal quenching temperature range(280 ~ 370? ?),low temperature of ferrite is fine needle,high temperature is feathery ferrite.The same sample surface hardness increased gradually with the wear and tear;Same Mn content,different surface hardness of the specimen with the temperature increasing of isothermal quenching temperature decreases,the total amount of wear increased,but the wear volume of the amplitude decreases;The same quenching temperature,such as surface hardness of ADI rise with the increase of Mn content,the total erosion rate decreases,and wear resistance increased.By scanning electron microscope and wear morphology group found that isothermal quenching temperature is 280?,the micro cutting wear is the main wear mechanism of cutting marks,good abrasion resistance;Isothermal quenching temperature is 310 and 340? ?,the micro cutting wear is the main wear mechanism of material,surface has a little furrows,cutting marks,erosion rate increases,the wear resistance;Isothermal quenching temperature is 370?,the worn surface materials have obvious cutting mark depth,along with a small amount of material peeling off,the wear and tear of material is given priority to with furrows,and a small amount of micro cutting.Same isothermal quenching temperature of ADI,when Mn content is 0.2% ~ 0.5%,the furrows and microscopic peeling is main failure form of the material;When Mn content is 0.8%,the failure form is given priority to with furrows and cutting.By analyzing the phase of the sample after wear,found that ADI under the action of friction stress strain hardening,retained austenite turns into martensite,which increases the surface hardness.Energy spectrum analysis found that ADI graphite ball will fall off to the surface of the friction pair in the organization,and form the anti-frictionlayer,improve the ADI abrasion resistance.