Study On The Microstructure And Properties Of Cast Iron Materials For Sintering Machine Trolley

The important component of the sintering machine is the trolley. And the features ofthe high chromium cast iron material are wear resistance, high temperature resistance andheat resistance. Therefore it is a good material for sintering machine cast iron.In the article, it is studied on the high chromium cast iron materials for the sinteringmachine trolley. It shows that the microstructure of the high chromium cast iron materialsfor sintering machine trolley is austenite, martensite, Cr7C3, Fe3C,(Cr,Fe)7C3by theAxiovert200MAT optical microscope, the S-4800field emission scanning electronmicroscope, the D/MAX2500PC X-ray diffraction and the energy spectrum analysis(EDS).In the article, it is analyzed the changes of the microstructure, hardness andoxidation resistance through the three different heat treatment processes:1) themicrostructure contains a lot of carbide and martensite under the500-900℃for thirtyminutes and then air-cooled. So with the heat treatment temperature increasing at500℃-600℃, the hardness is gradually increased and the oxide film is continuously thickened.The temperature of eutectoid transformation is700℃. When reaching the temperature,the most carbide and martensite are appeared, so the hardness reaches a maximum.Because the denseness of the oxide film is the best, it has the best oxidation resistance at700℃. When the temperature continued to rise, it appeared the decomposition ofmartensite and the remelting of carbide, then the hardness is gradually decreased and theoxide film appeared the microscopic cracks, lead to the weight increased. But there is noiron skin in this process.2) the secondary cementite has been precipitated from the highchromium cast iron materials for sintering machine trolley at500℃for twenty times.The martensite has been precipitated because it is poor carbon and poor chromiumaround the austenite. And there is a lot of residual austenite in this process. Because ofthe carbide and martensite, the hardness is increased. Due to the formation of the oxidefilm in the heating process, the material has good anti-oxidant.3) the microstructureappeared ferrite, a large number of carbide, a part of pearlite and martensite, and a smallamount of residual austenite at900℃for117hours. The hardness of materials decreasedbecause the dissolved speed of carbide is faster than the precipitation rate, the carbideaggregated and grew and the crystal of austenite grew. When the oxide film is thickeningand can not be attached to the surface of the material, it will be peeled off. So it has theiron skin.In the article, it discussed friction and wear properties of high chromium cast ironmaterials with the help of MG-2000high-speed and high-temperature friction and weartester. With the pressure load and rotational speed increasing, the friction coefficient isreduced. But the friction coefficient is increased because of the long running time. Withthe pressure load、rotational speed and running time increasing, the amount of wear ismore and more. Different friction surfaces have different friction mechanisms. There aremicroscopic cutting friction mechanism、 repeated plastic deformation frictionmechanism、fatigue wear and micro fracture mechanism for the friction mechanisms ofhigh chromium cast iron materials.