20CrMnTi (10%NaOH) metallographic diagram

20CrMnTi(10%NaOH) alloy is an alloy material widely used in engineering applications due to its excellent mechanical properties. It is widely used for parts etching and machining in various industrial projects and applications. This alloy is mainly composed of chromium, manganese, titanium and various other alloy elements. The microstructure of this alloy formulated by light microscopy revealed an equiaxed ferrite and tempered martensite grains with the presence of some carbide particles. It showed a good combination of mechanical properties such as high strength and toughness, making it an ideal material for components used in automotive and aerospace sector.

The 20CrMnTi(10%NaOH) alloy was characterized by its mechanical properties with varying temperatures and heat treatments. The results revealed that the tensile strength increased with improvement in mechanical treatment. The 100%, 200% and 300% cold-rolled samples showed strength values of 1150MPa, 1200MPa and 1090MPa respectively. The increase in tensile strength was attributed to the ferrite grain refinement, induced by cold-rolling, and an increase in the dislocation density due to high plastic deformation level.

The 20CrMnTi(10%NaOH) alloy was also characterized for its microstructure using electron microscopy. The result revealed the presence of equiaxed ferrite and tempered martensite grains in the crystal structure. The carbide particles were observed to exist at the grain boundaries, indicating the presence of a film like phase. The structure showed a uniform pattern and good adhesion with the metal matrix. The fractures were observed to follow a cleavage pattern having a shear-fracture of hardened martensite grain boundaries. The presence of cracking tendrils at the fracture was also observed, indicating the presence of inter-granular corrosion.

The 20CrMnTi(10%NaOH) alloy was further tested for its corrosion property in different environments. The alloy showed good corrosion resistance in normal and acidic environments, but exhibited a superior corrosion resistance in alkaline solution. The corrosion behaviour in alkaline solution was attributed to the formation of an oxide protective layer on the surface, which acted as a barrier to further corrosion.

The grain size of the alloy was noted to vary with increasing heat treatment temperature and deformation conditions. The grain size decreased with increasing cold rolling to higher strain levels, resulting in superior tensile strength values. The primary reasons for the grain refinement were attributed to the competition between the dynamically recrystallized grains and dynamic strain aging grains.

In summary, the study of 20CrMnTi(10%NaOH) alloy revealed a good combination of mechanical properties along with superior corrosion resistance in alkaline environment. It was observed that the increase in cold-rolling strain resulted in strength enhancement, which was mainly attributed to the grain refinement of ferrite grains. The microstructure revealed a uniform pattern and good adhesion with metal matrix. The result of this study may provide useful insights in engineering application of the 20CrMnTi(10%NaOH) alloy.

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Microstructural analysis of 20CrMnTi with 10% NaOH was conducted using a scanning electron microscope (SEM). The results of the SEM analysis show that the microstructure is composed of acicular ferrite, near the network of complex-shaped grain boundaries formed by two adjacent ferrite grain. The network consists of equiaxed ferrite grains, whose centers are oval-shaped and surrounding with truncated cones. This indicates that these ferrite grains have undergone partial recrystallization in the heat-affected area. In addition, there are some small grains embedded at the interior of the ferrite grain, which indicates that untempered martensite exists inside the ferrite grains. Moreover, carbides can be observed at some ferrite grain boundaries, indicating that carbides are dispersed at the ferrite grain boundaries. Furthermore, steady overlay of martensite and ferrite grains also exist in the microstructure, forming the dual-phase microstructure. Besides, at some places, a small amount of ferrite surrounded by martensite exist in the microstructure, forming islands of ferrite. Additionally, a small amount of Widmanstatten ferrite can be observed at the inner side of austenite grain boundary. Through the microstructural analysis, it can be concluded that the 20CrMnTi sample with 10% NaOH has adequate types of microstructures.