Study On Structure And Properties Of Modified Bearing Steel With Amorphous Nanocrastalline Fe-Based Inoculants

GCr15 is the most typical bearing steel,and its classic composition of 1%C-1.5%Cr has not been changed.Because GCr15 has high and uniform hardness,wear resistance,elastic limit,wide temperature range,good dimensional and shape stability,it is widely used in the manufacture of rolling bearings and rolling rings.The organization and performance of the bearing steel is critical to the proper operation of the bearings and equipment.With the development of modern industry,the demand for bearing steel performance in high-end cars,wind power,high-speed rail cars and aerospace industries is getting higher and higher.Therefore,people are eager to find ways to improve the microstructure and properties of bearing steel.Modification is one of the effective ways to improve the microstructure and properties of materials.The degree to which the modification treatment can improve the toughness of the materials.In this paper,two strip-shaped amorphous nanocrystalline Fe-based inoculants,Fe-Nb-Cr-C inoculant and Fe-Nb-Cr-C-N-B inoculant were prepared by in-situ autogenous and rapid solidification techniques.Then,the microstructures of the two inoculants were observed and analyzed.The test results show that a large number of ceramic particles are uniformly distributed in the matrix of the two inoculants.The process and role of nano-ceramic particles in two amorphous nanocrystalline Fe-based inoculants during non-uniform nucleation of bearing steel molten steel are also described.And the process of forming more M₇C₃type carbides(mainly Cr₇C₃)in the GCr15 matrix by the nano ceramic particles Cr₇C₃in the two inoculants.Compared with the traditional treatment process,the as-cast microstructure of GCr15 was significantly optimized after modification,and the grain size,the thickness of the reticulated carbide and the spacing of the flaky pearlite were significantly improved.Moreover,the improvement effect of Fe-Nb-Cr-C inoculant was better.After heat treatment,the grains of GCr15 were also significantly refined,the number of carbide particles increased significantly,the size of various carbide particles was significantly reduced,and the improvement effect of Fe-Nb-Cr-C inoculant was better.In terms of performance,the hardness,wear resistance,impact toughness and yield strength of GCr15 bearing steel were significantly improved.In particular,after the modification treatment,the tensile strength of GCr15 reached2025.7 MPa,and the elongation at break was about 1.54 times that of the no modification treatment GCr15.This paper provides data support for the modification process to simultaneously improve the strength and toughness of GCr15.It also provides valuable experience for other workers who study bearing steel.