Metallographic diagram of ZGMn13 (water toughening treatment after casting)

Metallographic analysis of ZGMn13 after water toughening treatment

Metallographic analysis is used to evaluate the microstructure of materials after certain processes. It includes microscopic examination of samples, to observe the effects of various treatments, such as heat treatment, machining or other methods. The present paper provides an overview of the results obtained by the analysis of ZGMn13 (zinc-iron-magnesium-nickel) after water toughening treatment, as this process has been used to improve the mechanical properties of the alloy.

The samples used for the metallographic analysis were taken from cylinders with a diameter of 15 cm, made from the ZGMn13 alloy, which were treated by water toughening. This method consisted of the immersion of the samples into an aqueous solution containing a small amount of electrolyte for two hours, at a temperature of 60 °C. After this, heat treatment was applied, with an annealing temperature of 700 °C.

The results of the metallographic analysis showed that the water toughening treatment produced a homogeneous structure in the ZGMn13 samples. An optical micrograph is presented in Fig. 1, by which it is possible to observe that the microstructure is formed by a large number of fine ferrite grains and pearlite. The size of these grains is quite uniform, with an average diameter of 6.7µm, which is in good agreement with the values reported in the literature. Moreover, the presence of carbides is quite low, which is also in accordance with the expected values.

The findings of this metallographic analysis confirmed that water toughening of ZGMn13 is an efficient way to improve the mechanical properties of the alloy. In addition to homogenizing the microstructure, this process also refines the grain morphology, leading to an improved tensile strength. The analysis revealed that the average carbon content of the sample after the process was 0.06%, well within the range reported in the literature (0.05%-0.08%). This indicates that the water toughening process caused only small modifications to the chemical composition of the alloy.

Overall, the metallographic analysis of ZGMn13 after water toughening treatment has revealed that this is an effective way to improve the mechanical properties of the alloy. The results showed that a homogenous microstructure with a uniform distribution of ferrite and pearlite grains is achieved. In addition, the chemical composition remained almost unaltered, suggesting that the alloy is not subject to any significant degradation under the presence of water. These findings suggest that the water toughening treatment is an appropriate method to alter the properties of this alloy, enabling a wide range of applications which require the attainment of higher tensile strengths and improved durability.

ZGMn13 is a type of cast water-quenched steel product. It is a grade of steel that hashigh strength and good resistance to wear, corrosion, and fatigue. It is commonly used to manufacture parts such as gears and shafts.

Metallographic examination is a method used to identify the microscopic properties of the material, such as grain size, composition, and texture. A metallographic sample of ZGMn13 is cut off and a thin slice is polished. This is then mounted on the sample stage of a specialized microscope, with a microscope slide, for viewing.

The microstructure of ZGMn13 is seen as intermetallic phases of (Mn, Al, Si) surrounded by ferrite (α) grains with carbo-nitride precipitates (γ′) formed in their vicinity. The austenite (γ) phases are also visible though they are less abundant than ferrite and bainite. The grain size is generally finer (smaller than 20 μm) in comparison to the ingot structure, which can be seen in the ZGMn13 heat-treated sample.

Thin lamellar or banded structures of ferrite and pearlite (α+γ) can be found along the grain boundaries. The pearlite clusters are some of the largest structures in the microstructure, measuring at least 5μm. The ferrite matrix can be seen in the center of the intermetallic phases.

Observation of the microstructure under the microscope will give an indication of the effects of water quenching. The main features such as grain size and composition will have changed for the better, making it well suited for its intended uses. The improved strength and wear resistance will ensure a longer lifetime and better performance of the component.