45Mn2 (1100℃×20min+350℃×3s water cooling) metallographic diagram

Metallographic Analysis of AISI 1045Mn2

A metallographic analysis is a process used to examine the microscopic structure of steel in order to gain an understanding of its behavior when under certain conditions. In this analysis, a sample of AISI 1045Mn2 has been subjected to an austenitizing treatment of 1100℃×20min followed by a tempering treatment of 350℃×3s water cooling. The objective of this analysis is to examine the microstructure of the steel after being subjected to these treatments and to understand its possible resulting fatigues keys and its behavior under certain conditions.

The sample of AISI 1045Mn2 was prepared for examination by polishing the surface with increasing grain sizes of SiC abrasive paper (FA-SiC 60, 80, and 120 for general metallography analysis) wet with a mixture of water and alcohol. The specimen was then etched with a 40 ml 2% Nital (HNO3: ethanol: water = 10:10:80) reagent solution and examined under an optical microscope (Olympus SZX10) at a magnification of 100X for metallographic analysis.

The micrographs obtained from the metallographic analysis of the AISI 1045Mn2 steel showed a predominantly bainitic microstructure with some regions of ferrite-pearlite structures. The predominately bainitic microstructure can be attributed to the austenitizing treatment, which allows for a prompt transformation of the austenite phase to a zone of heavily bainite. The ferrite-pearlite structures are typically associated with the tempering treatment, which increases the temperature of the material in order to reduce the hardness of the steel and to increase the toughness. This heat treatment causes the austenite phase to decompose to either ferrite or cementite, depending on the composition of the steel and temperature used.

The fatigue properties of the steel were determined using the Krivanek etching technique, which shows the various stages of martensite transformation in the steel. After treatment, the micrographs indicated that regions of martensite were present along the grain boundaries, which indicated high fatigue strength, however, there were also other regions within the grains, which indicated lower fatigue strength.

Overall, the metallographic analysis of the AISI 1045Mn2 steel revealed a predominantly bainitic microstructure with some regions of ferrite-pearlite structures. The Krivanek etching technique suggested that the steel has good fatigue properties with high fatigue strength at the grain boundaries and lower fatigue strength within the grains. The microstructural characteristics of the steel, as well as its fatigue properties, suggest that the material might be suitable for applications requiring strength and toughness.

The metallographic experiment of 45Mn2 steel was carried out. 45Mn2 steel is a heat-treatable steel with an approximate composition of 0.45C–1.5Mn–0.8Si–0.1V–0.4Cr–0.4N. In this experiment, the sample was subjected to a heat treatment of 1100℃×20min+350℃×3s water-cooling.

The grain of the 45Mn2 steel is fine and well distributed. There is no obvious segregation. There is segregation in the carbide particles, which are generally dispersed in the grain boundary and near the grain boundary. The carbide particles are mainly mottled spherical particles with an average spherical diameter of about 5μm. Inside the graphite was found in the form of flake-like, metallographic analysis shows that the graphite in the rolling and drawing of the combined effect of the ductile.

The constant known as the pearlite content of 45Mn2 steel was measured to be 52.8%. The pearlite is mainly distributed in the austenite grain boundary, generally in block or curved. The ferrite was excellently distributed in the pearlite, and the grain size (average grain size 2.7μm) was also relatively finer.

Overall, the microstructure of the 45Mn2 steel tested in this experiment is satisfactory. The grain structure is fine and well-distributed, the carbide particles are properly distributed, the pearlite content of the sample meets the requirements, the ferrite grain is finer and evenly distributed, and the graphite is formed in the form of flakes.