During the use of the wear-resistant pump body casting, the high-density hard particles move close to the cavity wall, thereby causing scouring and great friction damage to the inner wall of the flow-through parts. Therefore, the wear-resistant pump body casting itself needs to have high wear resistance. Wear resistant ductile iron is mainly obtained by alloying and heat treatment, and isothermally quenched ductile iron ADI is the most representative. The wear resistance of this ductile iron’s unique Austempered matrix is better than that of steel. However, in order to reduce costs, it is often necessary to add some alloy elements to the ductile iron to form a certain number of hardened phases to obtain the wear resistance when cast.
The main factors that affect the wear resistance of wear-resistant pump body casting materials are:
1) Hardness. The wear resistance of metal materials is usually measured by the hardness of materials. The depth of materials with high hardness pressed into the surface of materials is shallow, and the volume of abrasive chips produced by cutting is small, that is, the wear is small, and the wear resistance is high. All methods that can generally improve the hardness can also improve the wear resistance of materials.
2) Plasticity and toughness. High plasticity and toughness means that the material can absorb large energy, and cracks are not easy to form and expand. The material has a large ability to withstand repeated deformation, and is not easy to form fatigue spalling, that is, it has good wear resistance.
3) Strength. During the wear process, the metal matrix has high strength, which can provide good support for the anti-wear hard phase, give full play to the anti-wear ability of the anti-wear hard phase, and make the wear-resistant material show excellent wear resistance. Under the same hardness, high strength wear-resistant materials have better wear resistance.
4) Metallurgical defects such as inclusions. Metallurgical defects such as non-plastic inclusions in castings have a serious impact on fatigue wear. Nitride, oxide, silicate and other particles with edges and corners can not coordinate with the matrix to form voids during the process of stress, forming a source of stress concentration. Under the action of alternating stress, cracks appear and expand, and finally lead to early fatigue wear.
Therefore, in the production of wear-resistant pump body castings, on the premise of ensuring that the spheroidization is qualified, it is not only necessary to ensure that the mechanical properties meet certain requirements, especially the strength, hardness, plasticity and toughness, but also to ensure that the wear-resistant pump body castings are free of slag inclusion, air holes, shrinkage porosity, shrinkage holes and other defects, so as to ensure the wear-resistant performance of the wear-resistant pump body castings.