H6Mo5Cr4V2 (vacuum-treated, vacuum-sprayed TiN-coated after annealing) is a precipitation-strengthened stainless steel developed by Hot-work Research and Development Center of Chinas National Non-Ferrous Metal Industry Corporation. This steel is often referred to as H6Mo5Cr4V2p for its high light, strong and soft precap strength, sliding friction properties, wear properties and non-magnetic properties. The aim of this article is to display a microstructure examination of this steel.
First and foremost, the microstructure of H6Mo5Cr4V2p steel was observed using an optical microscope. The microscope reveals a uniform and fine grain structure in the steel, with grains that appear to be very small in size. Next, scanning electron microscopy (SEM) was used to examine the microstructure. A variety of phases were revealed in the images, including martensitic, bainitic and carbide phases. The martensitic phase was primarily composed of M6C carbides and had an average grain size of 0.5 μm. The bainitic phase also contained M6C carbides and had an average grain size of around 0.3 μm. Finally, the carbide phase was composed of M7C3 carbides and had an average grain size of 0.2 μm.
To further study the microstructure of H6Mo5Cr4V2p steel, X-ray diffraction (XRD) was used. Examination of the XRD patterns revealed the presence of several phases in the steel, including α-ferrite, M6C, M7C3, and γ/α-Cr2Mo. The α-ferrite crystallined in a body-centered cubic lattice and was located at the grain boundaries. The M6C, M7C3 and γ/α-Cr2Mo phases, on the other hand, were located inside the grains.
Finally, to further understand the microstructure of the H6Mo5Cr4V2p steel, a gold rolling light image (GRLI) was used. From the GRLI, a range of features including grain size, grain shape, grain size distribution and dendrite arm spacings (DAS) could be determined. The grain size was determined to be 0.5 μm, while the grain shape was found to be spherical. The grain-size distribution was found to be evenly distributed throughout the steel, with nearly equal numbers of large and small grains. Lastly, the DAS was found to be comparatively large, measured to be around 2.2 μm on average.
In conclusion, H6Mo5Cr4V2p steel was found to be composed of martensitic, bainitic and carbide phases. Optical microscopy, scanning electron microscopy, X-ray diffraction and gold rolling light imaging were used to further analyze the microstructure of this steel. These investigations revealed a range of features including grain size, grain shape, grain size distribution and darmite arm spacings. All of these features indicate that H6Mo5Cr4V2p steel is well-suited for applications such as cutting tools and knife blades.
