Correlation Between Microstructure and Fracture Behavior in Thick HARDOX 450 Wear-Resistant Steel With TiN Inclusions

    
    Introduction
    
    The use of Hardox® 450 wear-resistant steel has seen increasing popularity in various industries due to its improved wear resistance and mechanical properties. The addition of titanium nitride (TiN) particles as inclusions has been found to further enhance these characteristics and provide better fracture resistance. The correlation between microstructure and fracture behavior in Hardox® 450 wear-resistant steel with TiN inclusions has been studied in recent years with researchers finding results on the role of inclusions on hardness, wear resistance, fatigue strength, and fracture strength. This article will review previous studies on subject and further discuss the correlation between microstructure and fracture behavior of this steel.
    
    Microstructure of Hardox® 450 Wear-Resistant Steel
    
    The microstructure of Hardox® 450 wear-resistant steel consists of ferrite, austenite, and pearlite. The ferrite phase is the major component, making up approximately 90% of the microstructure’s volume. The other two phases, austenite and pearlite, are present in relatively smaller amounts. These two secondary phases form when the internal shrinkage of the austenite phase imparts stress to the ferrite phase, leading to the formation of pearlite.
    This microstructure consists of mainly ferritic martensite at the core and a thin layer of bainite at the surface. The addition of TiN particles as inclusions has been found to further reduce its brittleness.
    
    The Role of TiN Inclusions
    
    TiN particles are added to improve the properties of Hardox® 450 wear-resistant steel. It has been found to affect the mechanical properties such as hardness, wear resistance, fatigue strength, and fracture strength by reducing the maximum stress concentration and by reinforcing the material. In addition to these effects, it has been observed to reduce the rate of microstructural transformation, thereby increasing the fracture strength.
    
    Effect of Microstructure on Fracture Behavior
    
    It has been found that the microstructure plays an important role in the fracture behavior of Hardox® 450 wear-resistant steel. The fractography of the material has revealed that microstructure plays a major role in the rate of failure and the severity of fractures. It has been found that the ferrite phase contributes to the strength of the material and increases its fracture resistance. Similarly, the strengthening effects of austenite and pearlite have been observed to reduce the rate of microstructural transformation, leading to increased fracture strength.
    
    The addition of TiN particles as inclusions has been found to improve the fracture behavior of the material. This is achieved by the reduction of the maximum stress concentration, due to the formation of an inclusion zone surrounding the particle. Furthermore, it has been observed to increase the fracture strength by reinforcing the material, thus reducing the rate of microstructural transformation and the severity of fractures.
    
    Conclusion
    
    In conclusion, the microstructure of Hardox® 450 wear-resistant steel and the addition of TiN particles as inclusions play a significant role in the fracture behavior of the material. The presence of ferrite, austenite, and pearlite has been shown to contribute to the strength of the material, while the addition of TiN particles has been found to reduce the maximum stress concentration and further reinforce the material, thus increasing the fracture strength.

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