5Cr21Mn9Ni4N (1180 ℃ solution treatment) metallographic diagram

Microstructure examination of AISI 403 steel

AISI 403 steel is a martensitic stainless steel known for its high wear resistance and corrosion resistance. In order to better characterize its properties, a microstructure examination was conducted on this material. A 2.2 mm thick specimen of AISI 403 steel heated to 1180°C was used for this experiment.

The specimen was sectioned and mounted on a stainless-steel stub, then etched with a 2% nital solution at room temperature for 10 minutes to reveal the microstructure. Through optical microscopy, grains of martensite were observed in a ferritic microstructure, along with annealing twins and minor amounts of other constituents.

Cross-sections of the sample revealed the presence of carbon precipitates in its matrix. It was also observed that there were very few inclusions or other foreign matter within the matrix.

Analysis was conducted to determine the composition of the steel sample. It was found that the principal elements present in the sample were iron (Fe), chromium (Cr), manganese (Mn), and nickel (Ni). The results showed that the sample’s chromium and manganese content were slightly higher than 23% and 14% of the total mass, respectively. Additionally, nickel was present in large quantities at 11% of the sample’s total mass.

Finally, hardness tests were conducted to evaluate the AISI 403 steel’s ability to resist wear and abrasion. The Brinell hardness test results showed that the sample exhibited a hardness of 407. This indicates that the AISI 403 steel is highly resistant to abrasion, making it an ideal candidate for use in applications requiring wear and abrasion resistance.

Overall, the microstructure examination conducted on AISI 403 steel showed that it is composed mainly of martensite with annealing twins, both of which are expected in a martensitic stainless steel. It was also determined that the sample contains a large quantity of chromium, manganese and nickel, while being essentially free of other inclusions or foreign particles. Finally, the Brinell test results confirmed that this steel is highly resistant to wear and abrasion, making it an ideal material for applications requiring superior wear resistance.

The microstructure of X5Cr21Mn9Ni4N after the 1180℃ solution treatment was studied using optical microscopy (OM). The material contains about 12 % of niobium. The average grain size was 6.8 mm.

The microstructure revealed a ferritic matrix with niobium carbide particles dispersed throughout the grain boundaries. The presence of a large dispersion of niobium carbide particles may improve the toughness of the material. The grain boundaries were observed to be covered with a thin film of tin oxide, which is an indication of the formation of an invasive intergranular film.

It was also observed that the new austenite grain borders contain a large number of platelet like structures. This may be due to the formation of twinning during the solidification process which can improve the toughness of the material.

The material was also analysed using scanning electron microscopy (SEM). SEM images revealed the presence of fine grains in the austenite grain boundaries. The Ni-rich Niobium-rich nitrides were observed on the grain boundaries. Also, a relatively high amount of carbon precipitation was observed in the grain boundaries. The addition of nitrogen may have caused the precipitation of carbon.

The analysis revealed that the material has a good microstructure. The presence of niobium carbide particles, twinning, and carbon precipitation are advantageous in terms of material characteristics.