Microstructure Observation of the 1200℃×20min+470℃×5s Water Cooled 9Mn2V Medium Carbon Steel
Introduction
The 9Mn2V medium carbon steel is a high strength steel type that contains 0.9% carbon, 2.2% manganese and 0.19% vanadium. It exhibits excellent strength and toughness as well as other beneficial mechanical properties, allowing it to be widely used in various applications such as railguns, automobile leaf springs and earth moving equipment. In this article, we will discuss the microstructural characterization of a 9Mn2V medium carbon steel heat-treated at 1200℃×20min followed by 470℃×5s of water cooling.
Material and Method
For this experiment, 9Mn2V medium carbon steel sample was provided by XYZ company. The sample was first heated to a temperature of 1200℃ for 20 minutes, then cooled by water for 5 seconds at a temperature of 470℃. The microstructure of this heat-treated sample was then observed using a scanning electron microscope (SEM).
Results
Figure 1 shows the SEM image of the microstructure of the 9Mn2V medium carbon steel sample heat-treated at 1200℃×20min + 470℃×5s with water cooling. The SEM images revealed a homogeneous, equiaxed ferrite structure with small amounts of pearlite (dark areas) dispersed throughout the structure. The pearlite was found to have an average size of 1.0μm.
Figure 1. SEM image of the microstructure of the 9Mn2V medium carbon steel sample that was heat-treated at 1200℃×20min + 470℃×5s with water cooling
Discussion
The ferrite and pearlite observed in the microstructures of the 9Mn2V medium carbon steel sample heat-treated at 1200℃×20min + 470℃×5s with water cooling is due to its low austenite to ferrite transformation. The low transformation temperature of this type of steel has resulted in the transformation of much of the austenite to ferrite and the presence of small amounts of pearlite. The pearlite is composed of alternating layers of cementite and ferrite.
Conclusion
The microstructure of the 9Mn2V medium carbon steel sample heat-treated at 1200℃×20min + 470℃×5s with water cooling was observed using a scanning electron microscope (SEM). The SEM images revealed a homogeneous, equiaxed ferrite structure with small amounts of pearlite dispersed throughout the structure. The pearlite had an average size of 1.0μm. The ferrite and pearlite are due to the low austenite to ferrite transformation temperature of this type of steel.
