Development Of Cr-Mo Alloy Steels For Liner Applications And Assessment Of Its Wear Resistance

Mill was used in new building materials, refractory materials, chemical fertilizer, black and non-ferrous metal processing, cement, Portland products, as well as glass ceramics and other production industry widely. Liner was the primary wear parts of ball mill. Its consumption was tremendous and growing. the huge consumption was concerned very much. Making use of the ball mill liner with good wear resistance and long life was significant.In this paper, AΦ5.03×6.4m ball mill liner service life was 4,000 hours in Wisco group iron ore plant. Grinding efficiency was low and replacement liner frequently. Wear-resistant Cr-Mo alloy steels liner was developed. Composition, shape and smelting process of Cr-Mo alloy steels liner was designed. The relationship of organization and hardness, toughness , wear resistance was studied after quenching and tempering in different temperature. The reasonable treatment process was put forward. It was confirmed that the wear resistance of liner was better than the previous liner. Through the laboratory wear test and six-month industrial service test, the wear resistance of Cr-Mo alloy steels liner board and the iron ore previous liner board was compared, the two kinds of liner material wear-resisting mechanism were analyzed.In this paper, the composition of Cr-Mo alloy steels was 0.48 0.55% C, 2.0 2.5% Cr, 0.6 0.8% Mo, 0.8 1.2% Mn, 0.9 1.2% Si, 0.1 0.2% V, 0.15 0.2% RE. The Cr-Mo alloy steels had well hardenability, which thickness could reach 150mm. Its linear expansion coefficient is lower, which is 13.53×10^-6 / K. Austenitizing temperature Ac3 is 854℃. the best liner material quenching heat treatment process was 920℃quench +350℃temper. After 920℃quenching + 350℃tempering, the microstructure of test materials was acicular martensite + carbide + dispersed residual austenite, which carbide were mostly spherical or short pole shape. Its strength was high and toughness was good.The alloy steels liner board in the study had been used DaYe iron oreΦ5.03 x 6.4 m of ball mill. Cr-Mo alloy steels had better service effect than the previous liner steels. Life expectancy of Cr-Mo alloy steels liner would reach 7000 hours. Martensitic of Cr-Mo alloy steels was thin. It mutually thrust. Its dislocation density was high, that was positive effect to wear resistance. The previous liner steels had main base structure of the bulky martensite. It flaked easily and was brittle. Mo, V carbon were formed in Cr-Mo alloy steels, that increased the strength of steels and toughness and improved abrasion resistance. Points or globular carbide dispersion distribution in internal crystal, that strengthened the matrix, enhance the wear resistance. The long strips of carbide was main in the previous liner steels, that was dissolved in the more grain boundaries separating. So its toughness was low.