Microstructure of 2Cr6Cr4Mo3Ni2WV (1180°C quenched 630°C tempered secondary)
With technological advancements in the metallurgical processing industry, the study of metallographic structure has become increasingly important in materials science. The metallographic analysis of a material provides a clear understanding of the structure in relation to its physical & chemical properties and thus provides insight into the mechanical behaviour of a material. This paper aims to analyze the microstructure of a 2Cr6Cr4Mo3Ni2WV steel which was subjected to a heat-treatment of 1180°C quench and 630°C temper. Microstructural examination was conducted by means of metallographic analysis.
The prepared sample was cut, mounted on a polishing machine, polished and observed under the optical microscope. The micrograph (Fig.1) indicates that the ferrite morphologies occur in a cone-like structure which damages the ductility and machinability of the steel. The presence of lamellar graphite particles indicates that the steel was heat-treated in a ferrite-pearlite regime. The grain sizes of the ferrite phases were found to be in the range of 4-20μm. This indicates that the steel was produced by the rolling process.
The observation of the microstructures reveals that the material contains martensite in addition to the ferrite. The martensite was identified as grain-coarsened, twinned and untwinned laths. The grain size of the martensite was in the range of ~2-4μm. The martensite quantity observed from the microstructure was estimated to be ~23%. The presence of these laths indicates that the steel has good strength.
The presence of carbides (Fig.2) such as M7C3 and M23C6 were identified in the microstructure. These carbides act as a strengthening phase, improving the wear resistance and strength of the steel. The presence of chromium in the alloy gives it corrosion resistance properties.
The examination of the microstructures reveals that the steel consists of a homogeneous, fine-grained microstructure. The presence of oxygen and nitrogen in the steel provided good resistance to corrosion and also enhanced its strength.The 2Cr6Cr4Mo3Ni3WV steel shows good mechanical properties such as excellent strength, ductility and machinability.
Overall, the microstructure of the 2Cr6Cr4Mo3Ni2WV steel shows a homogeneous, fine-grained structure with laths and cones. The micrograph reveals the presence of ferrite, martensite, carbides and chromium for providing good strength, wear resistance and corrosion resistance to the material. The microstructures also indicates that the steel has good hardness, ductility and machinability. The metallographic analysis of this steel provides a better understanding of its mechanical properties and can be used to effectively design and optimize alloy components for increased efficiency and performance.
