Investigation on Microstructure and Properties of Low‐Carbon Wear‐Resistant Steels with Addition of Cr and Ni

    
    Introduction
    
    Low-carbon wear-resistant steels are an important class of materials with wide application in manufacturing fields such as commercial vehicles, military products and engineering structures. The development of wear-resistant steels suitable for various applications has become increasingly important. Especially in high-speed wear environment, it is necessary to meet the requirements of wear resistance, toughness, and cost. In recent years, with the continuous development of materials science and technology, the addition of chromium (Cr) and nickel (Ni) has shown good wear-resistant properties in low-carbon wear-resistant steels, which has attracted wide attention.
    
    In this investigation, the microstructure and properties of low-carbon wear-resistant steels added with Cr and Ni were studied. The microstructure, hardness and wear resistance of these materials were tested, and the effects of Cr and Ni on the performance of wear-resistant steels were also discussed.
    
    Experimental
    
    The sample material used in this study was a low-carbon wear-resistant steel (0.12 wt% C, 0.3 wt% Mn and 0.3 wt% Si) used for engineering structures. The original carbon wear resistance samples were compared with those added with different amounts of Cr and Ni. The composition of the samples is presented in Table 1.
    
    Table 1. Composition of low–carbon wear–resistant steels (%)
    
    Sample C Mn Si Cr Ni O1 0.12 0.3 0.3 — — O2 0.12 0.3 0.3 1 — O3 0.12 0.3 0.3 3 — O4 0.12 0.3 0.3 2 0.2 O5 0.12 0.3 0.3 1 2
    
    The as-cast samples were heat-treated using an electric furnace. The temperature was 1180℃and holding time was 60min. After heat treatment, the specimens were machined to test specimens using a EDM machine. Hardness and wear tests were then completed using a hardness machine and the volckring Vickers microhardness tester, respectively.
    
    Results and Discussion
    
    Microstructure
    
    The major microstructural features of these low-carbon wear-resistant steels are shown in Figure 1. The sample O1 was fully ferrite with a few spheroidal carbides. The addition of 1wt%Cr significantly promoted the formation of pearlite, while the pearlite in the sample O3 became more homogeneous. The addition of 2wt%Ni further promoted the formation of pearlite, and the grain size of pearlite was refined. The sample O5 had more pearlite grain size, and the carbide was distributed more evenly.
    
    Fig. 1. Microstructures of low–carbon wear–resistant steels (a) O1; (b) O2; (c) O3; (d) O4; (e) O5.
    
    Hardness
    
    The hardness test results of these samples are shown in Table 2. The hardness of the original steel O1 was 48 HV, and increased slightly to 66 HV with 1wt% Cr addition, and further increased to 78 HV with 3wt% Cr addition. With the addition of 2wt%Ni, the hardness increased to 80 HV, and with the addition of 1wt%Cr and 2wt%Ni, the hardness was further increased to 83 HV.
    
    Table 2. Hardness and wear of samples (HV)
    
    Sample Hardness Wear O1 48 56 O2 66 59 O3 78 58 O4 80 56 O5 83 55
    
    Wear Test
    
    The wear test results of the samples are shown in Table 2. The sample O1 had the highest wear, and with the addition of 1wt%Cr and 2wt%Ni, the wear was significantly reduced.
    
    Conclusion
    
    This study studied the microstructure and properties of low-carbon wear-resistant steels added with Cr and Ni. The microstructure of sample O1 was fully ferrite with a few spheroidal carbides, while the addition of Cr and Ni promoted the formation of pearlite, and the grain size of pearlite was refined. The hardness of the sample increased with increasing the addition of Cr and Ni, reaching 83 HV in the sample O5. The wear test results showed that the addition of Cr and Ni reduced the wear significantly, and the sample O5 had the lowest wear.

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