Microstructure and impact toughness of K360 wear-resistant steel welded joint HAZ

K360 wear-resistant steel welded joint heat affected zone (HAZ) is composed of two different phases, one is ferrite and the other is carbide-based solid solution, the microstructure of which is the basis of its improved mechanical properties. The impact toughness of K360 wear-resistant steel welded joint HAZ depends on the refinement and distribution of the ferrite and carbide-based solid solution phases.
    
Shows the microstructure of K360 welded joint HAZ. It is found that the HAZ contains a small amount of ferrite and a large amount of carbide-based solid solution phases, which are distributed uniformly in the HAZ. The ferrite content of the HAZ is mainly in the form of lath and granular structures, while the solid solution phases are mainly in the form of bainite, tempered martensite and coarse island-like structures. These mixed phases are all distributed in the HAZ in a random arrangement, forming a microstructure with a high degree of refinement, good strength and toughness.
    
The impact toughness of this K360 welded joint HAZ is mainly affected by the amount and distribution of the ferrite and carbide-based phases, the former providing toughness and the latter providing strength. Figure 2 shows that there is an increase of impact toughness when the ferrite content increases and the carbide-based solid solution content decreases. It is found that when the ferrite and carbides are uniformly distributed in the HAZ, the impact toughness is greatly improved and the decrease of impact toughness caused by the melting of welding metal and the production of brittle phases can be improved by increasing the amount and controlling the distribution of ferrite and carbides.
    
Microstructure of K360 welded joint HAZ
    
Relationship between impact toughness and ferrite & carbide-based solid solution content in K360 welded joint HAZ

In conclusion, the microstructure of the K360 wear-resistant steel welded joint HAZ plays a key role in determining its impact toughness. The impact toughness of the welded joint HAZ can be greatly improved by optimizing the amount and controlling the distribution of ferrite and carbide-based solid solution phases.

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