This paper summarized the research status and existing problems of automobile lightweight technologies at home and abroad from 3 aspects of structure lightweight, lightweight materials and manufacturing processes lightweight, mainly including the basic principle and research progress of size optimization, topological optimization and shape optimization in automobile structure lightweight, performance characteristics of lightweight materials and high-strength materials in material lightweight and application in automobile, basic principle and existing problems of manufacturing processes including hydraulic molding, laser welding and thermal forming. In terms of the current development trend, structural integration, research and development of lightweight materials with better comprehensive performance and adoption of more advanced manufacturing processes are important approaches to achieve automobile lightweight.

Due to energy and environmental issues, the global new energy vehicle industry has developed rapidly. High-strength steel, due to its advantages including high strength, excellent machinability, high cost performance ratio, its integrated application in new energy vehicles has become the focus of the industry. Based on the Early Vendor Involvement (EVI) concept, the upstream and downstream industry chain has carried out a number of steel lightweight body projects, such as POSCO PBC-EV, Thyssen In-car, ArcelorMittal S-in motion, Baosteel BCB series and Masteel MCEV, which mainly focus on the body and battery pack and other major components. In the future, with the electrification of the automotive industry, the implementation of energy saving and emission reduction policies and the maturity of key technologies, high-strength steel will play a greater role in the field of automotive lightweight.

The hybrid excitation rotor has higher process requirements in the production process. This paper discussed hybrid excitation rotor from 3 perspectives, i.e. how to correctly install the magnetic steel polarity in the manufacturing process, the identification of the magnetic polarity of the excitation coil and slip ring in the process inspection and the effect of different magnetic steel materials on the performance improvement. Through the combination of magnetic steel and claw pole arrays, a dedicated inspection equipment was designed to verify the excitation coil during the inspection process, different materials of magnetic steel were used for performance testing of the generator. The results show that combining the positive and negative poles of the excitation coil with the magnetic steel to form a Haier Beck array can effectively improve the output power of the generator, aluminum iron boron material has a better effect on improving electrical performance compared to ferrite.

Taking the magnesium alloy rear door of passenger car as the research object, the finite element software Comsol Multiphysics was used to establish the galvanic corrosion model of magnesium-steel dissimilar materials and simulate its galvanic corrosion behavior, the corrosion mechanism of magnesium-steel was analyzed by combining the results of electrochemical testing and corrosion morphology. Meanwhile, 4 anti-galvanic corrosion measures were formulated by combining the corrosion mechanism. These 4 anti-corrosion methods, including reducing electrolyte concentration, magnesium alloy surface treatment, reducing cathode area and adding aluminum alloy transition layer between magnesium and steels, can effectively inhibit the galvanic corrosion between magnesium and steels.

An investigation was conducted on the wrinkling of the paint coating on the weld sealant, it was determined that the cause of the wrinkling was poor wetting of the paint on the surface of the sealant. Through verification of material compatibility, influence of plasticizers, baking of sealants, comparison of different formulas of sealants and cross comparison of different film thicknesses in the middle surface coating, it is found that the cause for poor wetting is the thin film thickness of the paint coating. The fluctuation of robot spraying is the main cause for the thin film thickness. However, considering reducing the cost of spare parts and reducing the risk of sagging and foaming, the wrinkling problem was ultimately solved by improving the material’s wettability and an anti-recurrence solution was proposed.

For central black spot defect of molded bearing steel wire, the annealing state and hot-rolled state wire rod samples were tested by means of low acid leaching, metallographic analysis, Scanning Electron Microscopy (SEM) microstructure observation and energy spectrum analysis. By investigation of smelting and rolling process, it is confirmed that the central black spot problem is caused by poor heat preservation of heating agent, causing carbide segregation by element C and Cr concentration at the casting head. According to the causes of the defect, this paper proposed corresponding field process improvement measures, including changing the heating agent to strengthen the heat preservation of the casting head, reduce the pouring superheat, the central black spot defect was finally solved and the qualified rate of the product was increased.

Thermodynamic calculation software Thermo-Calc was used to calculate the influence of the change of Nb and Ti content on the precipitation behavior of carbon nitride, the composition of 1 800 MPa hot-formed steel was determined. The equilibrium phase diagram, the precipitation temperature of the main precipitated phase, the change of element content with temperature and the growth behavior of the precipitated phase were calculated, the basic data of the main phase composition and phase transformation characteristics were obtained. The mechanical properties and 3 point bending properties of microalloy 1 800 MPa hot stamping steel have been tested. The test results show that the steel has good toughness. The microstructure of the hot formed steel after quenching was characterized by Electron Back Scattering Diffraction (EBSD). The characterized results show that the small austenitic grains and small martensitic blocks are the main causes for the high toughness of the 1 800 MPa hot formed steel. Finally, the delayed fracture sensitivity of the hot-formed steel was measured by hydrogen filling and slow drawing method. The measured results show that the hot stamping steel has excellent delayed fracture sensitivity when the hydrogen filling time is less than 2 h.

Cr⁶⁺ is widely applied in automotive metal coating and leather, Cr⁶⁺ test is an indispensable index for the test of prohibited substances on automobiles. In order to test Cr⁶⁺ content in the metal coating of automotive materials, a rapid semi-quantitative detection procedure was established by the test strip method. Compared with ultraviolet method and point test method in QC/T 942—2021 Test Methods of Hexavalent Chromium in Automotive Materials, results of the strip test method are basically consistent with traditional qualitative and quantitative test methods. The advantage of strip test method is that the test can be completed within 5 minutes, far less than that of the traditional method that takes 4 to 8 hours. Meanwhile, operation of the test is simple, which saves large amount of test consumables and reduces waste discharge.

This paper studied and demonstrated feasibility of bio-based and degradable Polylactic Acid (PLA) as a substitute of petroleum-based engineering plastics in the fabrication of automotive interior parts. Through 1 year-damp-heat aging test, PLA demonstrated sufficient hydrolysis resistance and weather resistance, meeting the long-time service requirements of automotive interior parts. Through molding and performance verification as a ceilisng lamp shell, PLA was also confirmed to be suitable in automotive interior part design and development.

This paper introduced various kinds of conveying equipments of automobile welding lines, including high-speed rolling beds, servo sliding tables, reciprocating conveyor chain, stacked conveyor chain, air reciprocating conveyor and automatic guiding cart convey, introduced the application forms of various kinds of conveying equipment in welding line and the common application scenarios in the welding workshop. By explaining the principle and technical parameters of different conveying equipments, the paper expounded the basic usage concept of conveying form of welding line to ensure the rationality of equipment selection and improve factory efficiency.

The paper described in detail safety standards and risk diagram of automobile manufacturing industry, analyzed the risk level of human-machine interaction station in the welding line, it also introduced the principle and main parameters of safety light curtain, safety laser scanner and other safety equipments. According to the different application scenarios and safety distance calculation formula in safety standards, the paper derived the safety distances of feeding port and the repair station, providing relevant reference for welding line suppliers and automobile manufacturers on the safety construction of human-machine interaction process.