| Slurry pump is a common industrial pump used to transport the slurry with solid particles. It is impacted by the erosion wear of slurry for a long time. Its service life is greatly affected by the erosion wear performance of materials. In this paper, the Cr31hypereutectic high chromium cast iron can be used as the materials of slurry pump because of its high hardness and good corrosion resistance. While the erosion wear performance can be decreased due to the coarse carbides in as-cast as well as the lower hardness of matrix.In this paper, we explore the effect of quenching and tempering temperature as well as the modification treatments on the Cr31hypereutectic structure, hardness as well as the erosion wear properties. The simulation on the casting process of the pump are also performed based on the FEM software AnyCasting, the casting process models are established to avoid the casting defects. The results are as follows:The quenching treatment can promote the martensite transformation of as-cast matrix microstructure, as a result of the improvement of hardness of Cr31cast iron. In the temperature range of960℃1050℃,the hardness of the sample is decreased with increasing of quenching temperature; the secondary carbides are reduced gradually, and the amount of retained austenite is increased. The tempering treatment can significantly improve the erosion wear resistance of Cr31cast iron. In the temperature range of260℃-550℃,the hardness of the sample is increased with increasing of tempering temperature. As the temperature is450℃, the sample shows the best erosion wear resistance properties of cast iron. Secondary hardening happens during tempering process in a certain temperature range. The maximum of hardness decreases with increasing of quenching temperature, and its corresponding tempering temperature increases with increasing of quenching temperature. But higher tempering temperature can reduce the hardness of samples. The quenching&proper tempering temperature can significantly improve the erosion wear properties of samples.Re-Si-Fe alloy and silicon iron are added to the melts as the modificator to improve the shape and distribution of carbides in Cr31cast iron. The finding indicates that Re-Si-Fe alloy and silicon iron as the modificator can significantly improve the speciation distribution of the carbides. The addition of the two kinds of modificator to Cr31melts can not only refine the primary carbides, promote its uniform distribution, but also can significantly refine the eutectic structure. The hardness and the impacting toughness of the cast iron can be improved by adjusting size, shape and distribution of carbides. The hardness of samples are increased obviously after the heat treatment process of960℃quenching and450℃tempering.The casting process of pump shell is performed based on the AnyCasting softwere. The three elements of gating system∑Ag,∑Aru,∑As are designed as8.4cm2,22.4cm2,11.2cm2respectively. The size of three cylindrical risers are determined as (?)130x150mm and the size of one wedge riser are designed as the90cm2on the upper surface,18cm2on the lower surface, the height of the wedge rise is95mm. No any obvious defect of the casting can be found after solidification with ordinary cast iron casting. Such simulation process can provide a guidance for the casting process simulation of Cr31high chromium cast iron pump shell. |
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