In this paper, Thermo-Calc software was used for composition design, and the temperature control rolling control cooling process was formulated in combination with the Continuous Cooling Transformation (CCT) curve measured by thermal simulation. By reducing the oxygen content of electric furnace tapping, optimizing the soft blowing process of external refining and adopting protective casting measures, type A inclusion level of hot rolled wire rod ≤1.0, type B inclusion level≤0.5, type C inclusion level=0, and type D inclusion level≤1.0, type Ds inclusion level=0. Ferrite-pearlite microstructure can be obtained by controlled rolling, temperature and cooling process, with tensile strength ≥ 740 MPa, elongation ≥ 22%, surface shrinkage ≥52%, total decarburization depth≤0.10 mm, grain size level ≥ 9 and cold forging meeting 1/3 of the requirements without cracking. The results indicate that the non-quenched and tempered cold heading steel developed in this research can be simultaneously used to make automotive chassis components such as steering ball pins, Grade 10.9 bolts, and brake system guide rods.

In order to meet the energy-saving and emission reduction demand of commercial vehicles, important chassis components such as axles are developing towards high load-bearing, long lifespan and lightweight. A new type of microalloyed structural steel has been developed based on the traditional LZ27Mn2 steel grade for a 13 t trailer axle. A new car axle product has been successfully developed through new material development, structural optimization, heat treatment, and surface shot peening. Compared with the original axle, the new axle has successfully reduced weight by about 13.2%. Yield strength of the new axle matrix is≥800 MPa, tensile strength is≥860 MPa, elongation is ≥ 18%, impact energy at room temperature is≥130 J, and impact energy at -20 ℃ is ≥100 J. The new axle has been tested to meet the requirements for rigidity, strength (safety factor≥6.0) and fatigue life (1.2 million times) and meets the relevant technical requirements of the product.

In order to improve the simulation prediction accuracy of failure behavior of AHSS in vehicle crash, this paper studied the principle of 6 typical failure models such as GISSMO in mainstream LS-DYNA solver, it also studied the calibration methods of material fracture limit strain and mesh size regularization, the most crucial parameters affecting the failure behavior prediction accuracy of ultra-high strength steel during vehicle crash simulation. During the calibration process of fracture limit strain, average stress triaxiality should be used in order to describe the non-linearity loading paths. To overcome the limitations of default mesh size regularization method, the paper proposed a customized mesh size regularization method, which can effectively improve the consistency of simulation results for different mesh size models under typical stress states.

In order to avoid the patent limitation of hot stamping steel with traditional Al-Si coating, a new hot stamped steel with thin coating was developed. The mechanical properties of this steel sheet were ensured by strictly limiting the upper and lower limit of coating thickness. Tensile testing machine was used to verify the mechanical properties before and after heating, metalloscope was carried out to verify the microstructure and coating evolution before and after heating, the salt spray test was used to test the anti-corrosion property of steel sheet after hot stamping, welding glue applied on the existing production line was utilized to verify the glue matching properties of steel sheet, the existing production coating process was conducted to verify pre-treatment compatibility and electrophoretic coating performance of steel sheet. Result of all the verification indicates that the hot stamped steel with the new thin Al-Si coating meets the requirement of mechanical properties, anti-oxidation and anti-corrosion, in addition, it is compatible with the conventional welding and coating process.

This paper elaborated the anti-loosening method of adjusting nuts for automotive rack and pinion steering gears, and studied the riveting point method using riveting head to damage the threads of adjusting nuts. In this paper, the number of riveting head, the distribution of riveting head, and the riveting pressure were used as control variables, and the loosening torque of the adjusting nut after riveting, the deformation of the pressure block hole of the steering gear housing were utilized as evaluation indicators. According to the test, when 6 riveting heads are evenly distributed on the pitch diameter circle of the adjusting nut thread circumferentially to rivet the steering gear nut, the deformation of the pressure block hole of the housing is less affected, and the locking torque of the adjusting nut is also less affected. Finally, the method of adjusting nut riveting point for steering gear is obtained, in which 6 rivet heads are uniformly distributed on the pitch diameter circle of the adjusting nut thread along the circumferential direction, with riveting pressure of 30 kN riveting pressure as optimal.

Based on the exploration of the application of aluminum alloy in automobile parts, the basic situation of aluminum enterprise distribution, aluminum alloy composition elements, properties and processes are summarized. The commercialized application of aluminum in automobiles, especially in car bodies, is summarized. This paper proves the superiority and applicability of aluminum in automobile application, and summarizes the common methods of connecting aluminum parts with different and same materials. Research shows that the research and development of high-performance aluminum needs to be strengthened compared to foreign companies, and the diversification of automotive materials is constantly expanding in the field of lightweight, but the application of aluminum is still mainstream.

This paper discussed the product process design and welding defects debugging method of the laser brazing for the roof of Body In White (BIW) based on the industrial practice and application of the laser brazing of the BIW roof in Dongfeng Honda Automobile Co., Ltd., and focused on product structural design of the laser brazing of roof, component dimension accuracy control, production line process planning and plane layout of roof laser brazing, welding defects debugging method, manual inspection and repair process. By comprehensive introduction of process design and defect debugging method of laser brazing for BIW roof, the paper provided technical reference of laser brazing product design and process planning for subsequent new vehicle roof.

This paper elaborated the current situation of the application of aluminum alloy integrated die casting technologies in new energy vehicle enterprises and the planning of integrated die casting in mainstream new energy vehicle enterprises, it is concluded that the integrated die casting technology has obvious advantages in production efficiency, cost reduction, weight reduction and other aspects, and die casting machine will replace the welding robot as the core equipment of new energy vehicle manufacturing. It also indicates that the core of the integrated die casting technologies is the performance of large die casting machine, the formula of heat-free material, die casting die design and die casting process parameters. The research result shows that aluminum alloy integrated die casting will replace the manufacturing technology of body stamping and welding, the paper recommends that new energy vehicle enterprises that do not use integrated die casting should plan the integrated die casting technologies in advance.

To enhance the product maturity and solve the problems found in manufacturability analysis, product manufacturability baseline and mechanism were established. The first version of baseline was established through clarifying the scope, developing template, identifying source, confirming dimension, refining content, process confirmation, design confirmation, release and maintenance. Relevant activities such as identification, analysis, evaluation, and accumulation were integrated with the product development process to ensure the procedural application of baseline in the project. Combined with the product development project, the effect of baseline establishment and application were verified, improving the standardization, accuracy, and comprehensiveness of manufacturability analysis, improving product quality and production efficiency, as well as reducing manufacturing costs. At the same time, future expectations for the digital application of baselines were proposed.

This paper discussed the rationality of structural technology design of the parts from the aspects of modeling feature, slope and rounded corners, proposed precautions for process surface design from aspects such as process surface construction and settings, elaborated on blank design to solve the problem of low material utilization rate through laser cutting and layout, the paper also elaborated on the development risks and control involved in hot stamping formability analysis from CAE simulation process. The paper explored the hot stamping forming process technology involved in the development process of integrated door ring from the above 4 aspects, providing reference experience for the development of integrated door ring process technology, in order to solve the relevant problems in the development process, and also better reduce its development cost and shorten its development cycle.