Comparison of Sliding Wear Properties of 400 Grade Low Alloy Wear-resistant Steels with Different Microstructure

    
    The development of wear-resistant steels with improved performance has enabled designers to select materials with increased strength, hardness, wear resistance and abrasion properties for use in components such as machine tools, excavator buckets, agricultural equipment and other high-wear parts. The study of the sliding wear properties of 400 grade low-alloy wear-resistant steels with different microstructure can enhance the understanding of material selection and the application of wear-resistant steels for a variety of applications.
    
    The main aim of this study was to compare the sliding wear properties of 400 grade low alloy wear-resistant steels with different microstructures. Specifically, the Hardox 400, Weldox 700 and Domex 700 wear-resistant steels were selected to compare their respective sliding wear properties in dry sliding conditions at room temperature. The wear tests were carried out using a pin-on-disk tribometer at a normal load of 400N, sliding distance of 42km, sliding speed of 0.9m/s, and temperature of 25°C.
    
    The microstructure of the test specimens is shown in Figure 1. Hardox 400 is a quenched and tempered wear-resistant steel with a mass fraction of 0.44%C and 0.45%Mn. It has a complex microstructure consisting of uniformly distributed fine carbides in a ferrite and pearlite matrix. The microstructure of Weldox 700 consists of medium-sized carbides distributed in a ferrite/martensite matrix. The Domex 700 was quenched and tempered with an additive element Ni. The microstructure can be classified as fine tempered martensites with minor precipitates.
    
    Figure 1. Microstructures of the tested steels
    
    The wear experiment was conducted using a pin-on-disk tribometer which is able to apply the preset normal load of 400N on the test specimens. A reference disk of a worn steel was used as the counter specimen and its wear factor was kept constant throughout the experiment. The wear loss of each test specimen after the pre-determined sliding distance was measured and recorded. The dry sliding wear test results show that the wear resistance of Hardox 400 is the best among the tested steels (Figure 2). This can be attributed to its homogeneous distribution of fine carbides throughout its microstructure, which provides a higher wear resistance than the other materials due to its good resistance to abrasive and adhesive wear.
    
    Figure 2. Comparison of the sliding wear losses of the tested samples
    
    The sliding wear resistance of Weldox 700 and Domex 700 steels are similar and the wear resistance of Domex 700 is slightly better than Weldox 700, which can be attributed to its fine tempered martensite matrix with minor precipitates. It is known that the addition of Ni increases the wear resistance of steels due to its high hardness and low wear rate.
    
    In summary, this study showed that the Hardox 400 has the best sliding wear resistance among the tested materials. Its homogeneous distribution of fine carbides in a ferrite and pearlite matrix provides a higher wear resistance compared to the other steels. The sliding wear resistance of Weldox 700 and Domex 700 steels are similar and the wear resistance of Domex 700 is slightly better due to the addition of Ni which increases its wear resistance. Therefore, these findings can be employed by car manufactures, machine tool makers and other engineering industries to select the best wear-resistant materials for their applications.

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