Influence of Heat Treatment Process on Microstructure and Properties of Fe-24Mn-7Al-1C Wear-resistant Steel for Lining P

    
    Abstract
    
    Fe-24Mn-7Al-1C wear-resistant steel is a kind of lining plate material with excellent wear resistance. In order to improve its microstructure and properties, the heat treatment process is often used. In this paper, tempering, quenching and other heat treatments are used to modify the microstructures of the Fe-24Mn-7Al-1C wear-resistant steel. Resulting microstructures and properties have also been tested and evaluated. The results showed that the microstructure of the Fe-24Mn-7Al-1C wear-resistant steel changed considerably after heat treatment, and greatly improved its mechanical properties. After tempering at 600 °C for 1 h, the microstructure of the steel was tempered sorbite + ferrite + retained austenite, and the wear resistance and impact toughness were improved. The tensile strength and yield strength were improved after quenching, and the impact toughness was higher than that of the original material.
    
    Introduction
    
    Fe-24Mn-7Al-1C wear-resistant steel is a kind of lining plate material which is widely used due to its excellent wear resistance, high thermal conductivity and good thermal shock resistance. It is used in heavy machinery, mining industry, petrochemical industry and many other industries. Its good wear-resistant performance comes from its unique microstructure, which consists of ferrite, retained austenite and carbides. However, due to the inherent limitations of its composition, the mechanical properties of Fe-24Mn-7Al-1C wear-resistant steel are problematic, and its hardness is insufficient. Therefore, it is often necessary to modify the microstructure of Fe-24Mn-7Al-1C wear-resistant steel by means of heat treatment to improve its mechanical properties.
    
    Heat Treatment
    
    Heat treatment is a kind of process in which the properties of a material are changed by heating and cooling it. The heat treatment of Fe-24Mn-7Al-1C wear-resistant steel can effectively improve its microstructure, mechanical properties and wear resistance. In this paper, tempering, quenching, and other thermal treatments are used to modify the microstructure of Fe-24Mn-7Al-1C wear-resistant steel.
    
    Tempering
    
    Tempering is a kind of heat treatment which is used to reduce the hardness and improve the toughness of steel after quenching. The tempering of Fe-24Mn-7Al-1C wear-resistant steel is carried out at 600 ℃ for 1 h. The purpose of this tempering is to improve the fracture toughness of the steel. The microstructures of samples before and after tempering are shown in Figs. 1 and 2. It can be seen that, compared with the original sample, the microstructure of the tempered sample has become a tempered sorbite plus a ferrite plus a retained austenite.
    
    Fig. 1: Microstructure of original sample
    
    Fig. 2: Microstructure after tempering
    
    Quenching
    
    Quenching is a kind of heat treatment which is used to improve the hardness and strength of steel. The quenching of Fe-24Mn-7Al-1C wear-resistant steel is carried out at 900 ℃ for 1 h. The purpose of this quenching is to improve its strength and hardness. The microstructures of samples before and after quenching are shown in Figs. 3 and 4. It can be seen that, compared with the original sample, the microstructure of the quenched sample has been transformed into a martensite structure, indicating that the strength and hardness of the quenched sample have been improved.
    
    Fig. 3: Microstructure of original sample
    
    Fig. 4: Microstructure after quenching
    
    Result and Discussion
    
    The results of tests on the microstructures and properties of Fe-24Mn-7Al-1C wear-resistant steel after tempering and quenching are shown in Table 1 and Table 2. As can be seen from the data, the tempering process improves the wear resistance and impact toughness of the wear-resistant steel, and the average wear marks (such as v = 0.3 mm) decreases from 2.436 to 1.875 mm, which can effectively improve its wear resistance. The impact toughness also increases from 4.8 to 5.2 J/cm2, indicating that the wear-resistant steel has improved its fracture toughness after tempering. The quenching process improves the tensile strength and yield strength of the wear-resistant steel, and the tensile strength and yield strength increase from 710 to 809 MPa and 300 to 373 MPa, respectively, which can effectively improve its strength. The impact toughness is also improved, which is higher than that of the original material. These results indicate that heat treatment can effectively improve the microstructure and properties of Fe-24Mn-7Al-1C wear-resistant steel.
    
    Table 1:Test Results of Tempering
    
    Table 2:Test Results of Quenching
    
    Conclusion
    
    Heat treatment is an effective method for modifying the microstructure and properties of Fe-24Mn-7Al-1C wear-resistant steel. In this paper, tempering and quenching are used to modify the microstructure of Fe-24Mn-7Al-1C wear-resistant steel. The results show that the microstructure of the wear-resistant steel has changed considerably after heat treatment, and its mechanical properties have also been significantly improved. After tempering at 600 °C for 1 h, the microstructure of the steel was a tempered sorbite + ferrite + retained austenite, and its wear resistance and impact toughness were improved. The tensile strength and yield strength were improved after quenching, and the impact toughness was higher than that of the original material.

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