Work

Study on the influence of residual temperature normalizing process on the performance of automotive hub bearing forgings

Year: 2025

Type: article

Abstract: 55 steel is a commonly used material for flanged parts of passenger vehicle hub bearings in China. Generally, it is used after normalizing treatment following hot forging forming. To address issues such as high energy consumption, coarse grains, and low yield strength of the traditional normalizing process, this study systematically verified the feasibility of the residual temperature normalizing process for Grade 55 steel hub bearing forgings. Through comparative analysis of the mechanical properties, riveting port deformation capacity, and bending fatigue life of hub bearing units between the residual temperature normalized parts and conventional normalized parts, it was found that the residual temperature normalized parts showed a 5% increase in tensile strength (from 740 MPa to 856 MPa) and a 3%-5% increase in hardness (HBW 215-230). The austenite grain size reached Grade 9 (Grade 7 for conventional normalized parts). The riveting port showed no cracks after 75% compressive deformation, and the qualification rate of 50 riveted products was 100%. In the bending fatigue test, the residual temperature normalized parts fractured after 429,000 cycles under a strengthened load of 3,225 Nm, which was significantly better than that of the conventional normalized parts (51,000 cycles). The research indicates that residual temperature normalizing can achieve the dual goals of energy conservation, consumption reduction, and performance improvement by controlling the high cooling rate (10℃/s ± 2℃/s) at the initial stage of forging stop and the ferrite precipitation amount (F=8%-15%), providing a theoretical basis for the optimization of hub bearing unit manufacturing processes.

Source: Journal of Materials Research and Technology

DOI: 10.1016/j.jmrt.2025.11.066

Authors: Chaofan Sun, Guojin Cao, Haibing Fu, Feng Chen, Jianghua Huang, Hongchao Ji

Institutions: North China University of Science and Technology, Zhejiang University of Science and Technology

Language: English

Topic: Microstructure and Mechanical Properties of Steels

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,640

Funder: National Natural Science Foundation of China