Study On Corrosive-Wear Characteristics And Mechanism Of Carbidic Austempered Ductile Iron

Carbidic austempered ductile iron, so-called CADI, is a new kind of wear resistant ductile iron material. Comparing to traditional materials of mining, like chromium-alloy white cast iron, CADI has higher hardness and higher wear resistance and longer impact fatigue life.A systemic research of CADI used for grinding ball was done in this paper. According to the actual working environment in the mine, a simulation study of CADI was done in this paper. Mainly on corrosion and wear properties of different austempered temperature of CADI in different corrosion medium. Samples of the structural constituent, mechanical properties and surface morphology, respectively tested by scanning electron microscope, metallographic microscope, X ray diffracmeter and hardness tester et al. Corrosive wear surface topography and the corrosion morphology were observed by scanning electron microscope, residual austenite content was analyzed by XRD.The work include:electrochemical corrosion test, three body corrosive wear test, corrosive impact abrasion test. Mainly includes the effect of corrosive medium and austempered temperature on the corrosive wear of CADI.Research results show that:(1) In the test range (210℃～300℃), as the rising of the austempered temperature, the hardness of CADI decreased. The residual austenite and its carbon content both increased with the rising of austempered temperature.(2) As the rising of the austempered temperature (210℃～300℃), the electrochemical corrosion performance decreased, and arriving its minimum at240℃, then it begin to increase while the temperature rising continually, the corrosion resistance of CADI arriving its best at300℃.(3) In the no-impact corrosive wear test, the result of wet sand rubber wheel abrasion test showed that, as the rising of the austempered temperature, the corrosive wear resistance of CADI decreased, and arriving its minimum at240℃, then it begin to increase while the temperature rising continually.(4) The erosion-wear and corrosive impact abrasion performance of CADI showed a trend of decrease first then rising.(5) In different corrosive medium, the results showed that:In weak acid solution, due to the promotion of wear tear to corrosion and corrosion-wear interaction, CADI showed poor corrosion resistance. In weak alkaline medium CADI showed better corrosive wear resistance than in acid solution.