Abstract
The hot ring rolling technology as the crucial procedure for the manufacture of bearing rings plays an important role in determining the final microstructure of bearing rings. In this work, the influence of the hot ring rolling process on the microstructural evolution of 100Cr6 bearing rings was investigated using a three-dimensional (3D) numerical model and microstructural characterization. It was found that the significant microstructural refinement occurs at the different regions of the rings. However, owing to the non-uniform plastic deformation of hot rolling, the refinement rate of grain size and decrease of pearlite lamellar spacing (PLS) also showed uniformity at different regions of the rings. Furthermore, the degree of grain refinement had been limited with the increase of rolling reduction. Due to the refined grain size and decreased PLS, the Vickers hardness increased with the increase of rolling reduction. Moreover, the Vickers hardness from the outer surface to the inner surface of the ring is asymmetrical u-shaped, which had the law of lower hardness in the center area and higher hardness on the surface.
Highlights
Hot ring rolling is an advanced incremental metal-forming process
To analyze the evolution and distribution laws of grain size, pearlite lamellar spacing (PLS) and Vickers hardness, a series of experiments of the hot rolling ring with ball groove are conducted by performing electron backscatter diffraction (EBSD) and scanning electron microscope (SEM) technologies
The grain size is significantly reduced compared with the initial state (Figure 4a), and the grain size decreases obviously with the increase of rolling reduction
Summary
Hot ring rolling is an advanced incremental metal-forming process. The rings manufactured by hot ring rolling have the characteristics of high geometric accuracy, energy and raw material saving, and have outstanding microstructure performance [1,2]. Zhu et al [10] put forward four blank design principles for conical-section ring rolling and the dimension effects of blanks on dimensional accuracy and thermo-mechanical parameters distribution were explored. For 100Cr6 bearing steel during hot ring rolling forming, most of the research mainly focuses on the metal flow law and control method [21,22,23]. To analyze the evolution and distribution laws of grain size, pearlite lamellar spacing (PLS) and Vickers hardness, a series of experiments of the hot rolling ring with ball groove are conducted by performing EBSD and SEM technologies. A three-dimensional (3D) finite element (FE) model of hot ring rolling is established to illustrate the evolution of effective plastic strain and the effect on the microstructure. According to the analysis of the experimental and simulative results, the microstructure evolution of hot ring rolling is revealed
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