Effects of different water-based quenching media on microstructure and wear resistance of ZG30CrMnSiMo low alloy steel

The quenching of a material is a process of rapidly cooling it from a higher temperature to below its critical temperature to form a hard and wear resistant material. Its use is widespread in the heat treatment of metals and alloys. Quenching is typically achieved by the use of a water based quenching medium, such as water, oil, brine, or polymers. However, different quenching media may have an effect on the microstructure of the quenched material, and subsequently its properties. This article explores the effect of different water based quenching media on the microstructure and wear resistance of ZG30CrMnSiMo low alloy steel.
    
ZG30CrMnSiMo steel is a low alloy steel containing high levels of carbon, manganese, silicon and molybdenum. It is widely used in a variety of engineering components, owing to its excellent strength, toughness and wear resistance properties. The strength and wear resistance of this alloy can be further enhanced by heat treatment. One such technique is quenching and tempering, which involves cooling the material from an elevated temperature to a lower temperature, followed by further heating to produce a more homogeneous and harder material.
    
The quenching process largely determines the microstructure and properties of the steel. Different quenching media have contrasting cooling rates, affecting the material’s microstructure and its corresponding properties. In the present study, four water based quenching media – polyalkylene glycol, plant oil, synthetic oil, and brine – were used to examine their effect on the microstructure and wear resistance of the ZG30CrMnSiMo low alloy steel.
    
The four quenching samples were prepared as follows. After quenching, optical microscopy was used to observe and analyse the microstructure. Wear testing was conducted to evaluate the wear resistance of the four quenched samples.
    
The results demonstrate that polyalkylene glycol produced a microstructure with small and uniformly distributed grains, while the sample quenched with brine showed a much larger grain size. Both oil based quenching media produced similar microstructure, with slightly larger grain sizes than those of polyalkylene glycol. With regard to wear resistance, the brine quenched sample had the highest wear resistance. On the other hand, the sample quenched with polyalkylene glycol had much lower wear resistance than the former.

The results obtained from this study indicate that the water based quenching media had a significant effect on the microstructure and wear resistance of the ZG30CrMnSiMo steel. The microstructure and wear resistance of the steel was found to be influenced by the cooling rates of the quenching medium, with brine providing the highest wear resistance. This could be attributed to its faster cooling rate, which leads to finer and more uniformly distributed grains in the material.
    
In conclusion, the use of water based quenching media had a significant effect on the microstructure and wear resistance of the ZG30CrMnSiMo low alloy steel. In particular, brine had the highest wear resistance among the quenching media tested, owing to its faster cooling rate. However, further studies are necessary to evaluate the effect of the different quenching media on the mechanical properties of this material.

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