Abstract
The present research study was conducted to investigate the composition and microstructure of the 86CrMoV7 cold-work rolls’ steel billet. To identify the appropriate composition and properties of the material for production of cold work rolls, a thermite process was adopted for refinement and homogenization of the 86CrMoV7 steel billet under certain temperature conditions. The structure and morphology of the billet were studied by metallographic techniques and techniques such as metallography, X-ray diffraction and scanning electron microscopy (SEM). The results of the investigation showed that the 86CrMoV7 steel billet had a ferritic matrix with a small number of dispersed carbides. The size, shape and number of carbides varied depending on the chemical composition of the material and the homogenization temperature. Additionally, no impurities or inclusions were found in the billet. The grain size of the billet was medium, and the billet had a higher porosity level. These characteristics of the 86CrMoV7 steel billet contributed to its higher strength, plasticity and wear-resistance.
Keywords: 86CrMoV7 cold-work ranges, Structure, Morphology, Metallography, X-ray diffraction,Scanning electron microscopy.
1. Introduction
Cold-work rolls are used to deform materials because of their superior strength, plasticity and wear-resistance. Due to the essential role cold-work rolls play in the production of various products, it is essential to use suitable materials for their fabrication and ensure that the cold-work rolls possess the requisite characteristics. 86CrMoV7 steel is one of the widely used materials in the production of cold-work rolls and is expected to have certain properties like high strength, optimum toughness and good wear resistance.
Therefore, the aim of this research was to investigate the composition and microstructure of the 86CrMoV7 cold-work rolls’ steel billet and to identify the appropriate composition and properties of the material for production of cold work rolls. Thermite process was adopted to refine and homogenize the 86CrMoV7 steel billet. The structure and morphology of the billet were studied by metallographic techniques and other techniques such as X-ray diffraction and scanning electron microscopy (SEM).
2. Experimental Procedure
The 86CrMoV7 cold-work roll steel billet was prepared for the investigation. The steel billet was subjected to a thermite process for refinement and homogenization under certain temperature conditions. Subsequently, samples were cut from the steel billet for the study. The samples were prepared by grinding and polishing them on a polishing machine by successively using emery papers of increasing grade and diamond suspension of 2µm at the end.
To observe the structure and morphology of the 86CrMoV7 steel billet, optical microscope, X-ray diffraction and scanning electron microscope (SEM) were used. The metallographic results were compared with those of standard samples to determine the structure and morphology of the steel billet. The Grain size of the billet was determined under the optical microscope.
3. Results and Discussion
The metallographic results of the 86CrMoV7 cold-work roll steel billet indicated that the billet had a ferritic matrix. The matrix was composed of small dispersed carbides of different sizes, shapes and numbers. The carbides occur as separate, elliptical-shaped entities surrounded by a solid matrix of ferrite. Depending on the chemical composition of the material and the homogenization temperature, the size, shape and number of carbides varied. In addition, no impurities or inclusions were found in the billet.
The X-ray diffraction results of the 86CrMoV7 steel billet demonstrated a ferritic structure. The peaks exhibited in the diffraction pattern were similar to those predicted for metallic ferrites.
The grain size of the 86CrMoV7 steel billet was medium, and the billet had a higher porosity level. The porosity was attributed to the gas pockets formed during the thermite process.
The scanning electron microscopy results of the 86CrMoV7 steel billet revealed that the matrix of the sample was composed of fine carbide particles. The morphology of these particles was novel and shaped like rods, discs and flakes of different sizes. The matrix of the billet also had small pores in it.
4. Conclusion
The present study was carried out to investigate the composition and microstructure of the 86CrMoV7 cold-work roll steel billet. The thermite process was adopted for refines and homogenization of the 86CrMoV7 steel billet. The metallographic, X-ray diffraction and SEM results indicated that the billet had a ferritic matrix with small dispersed carbides of various sizes, shapes and numbers. The grain size of the billet was medium and the billet had a high porosity level. The results of the present study will be helpful in selecting a suitable material for production of cold work rolls with desired properties.
