The Effects Of Heat Treatment And Alloying Elements On Microstructure And Properties Of Hign Chromium Cast Iron

In this paper, according to the different heat treatment on the different tapes of hign chromium cast iron and those added some usefull alloys, the effects of the heat treatment and adding alloys on properties of the hign chromium cast iron were studied. By means of the metallographic microscope, X-ray diffraction(XRD) and scanning electron microscope(SEM), followed with Vickers hardness test, impact toughness test and sliding abrasion test, the microstructure and the properties of the hign chromium cast iron were analyzed, The results showed that:(1)After the quenching process at different temperature for 3h, and the tempering process at 250°C for 2 h on the Cr22 hign chromium cast iron, the microstructure of the experimental material were made up of tempered martensite, retained austenite and carbide. The hardness and abrasion resistance increased first as the quenching temperature increased, and they have decreased after 980°C. Therefore, when the quenching temperature reached 980°C, the hardness reched the maximum value. Meanwhile the Cr22 had the best resistance at 980°C.(2) After the quenching process at 1050°C for 3 h, and the tempering process at different tempering temperature for 2 h on the Cr22 hign chromium cast iron, the microstructure of the experimental materials were changed at the different temperature, as the tempering temperature increased, the microstructure were tempered martensite, tempered troostite and tempered sorbite in turn. At the 150°C and 550°C, the hardness reached the peak. Expecially at 550°C, It reached the largest value with the secondary hardening behavior. After 550°C, it has been decreased. when the tempering temperature was 550°C, the Cr22 had the best wear resistance.(3) After the softening process on Cr22, the microstructure of the sample was made up of pearlite and carbide. The hardness reduced significantly, but the impact toughness was better.(4) The study indicates that the hign chromium cast iron which is added 1% Nb or 1% Mo during aging treatment has lower hardness and better wear resistance than the unadded alloys material. But under the thermal refining carbon-steel, because of secondary hardening the hardness of the material that added alloy were much higner than unadded. It appeared the small NbC particles when added the Nb alloy and promoted the wear resistance. there will be less abrasion resistance and more hardness in the high chromium cast iron adding in 1%Mo than adding 1%Nb. In a word, It can promote the properties after adding the alloy in the hign chromium cast iron.