Research Progress on Hot Stamping Process of High Strength Aluminum Alloy Plates for Automotive Parts
In recent years,with the rapid development of the global economy,the energy crisis,environmental pollution,green-house effect and other issues have become increasingly prominent,as well as people's attention to environmental protection,energy conservation and emission reduction,and China's concept of carbon peaking and carbon neutralization,fuel vehicles,as a major pol-luter of exhaust emissions,further improve the requirements for vehicle lightweight.Aluminum alloy is the preferred material for auto-mobile lightweight because of its light weight,high strength,recyclability and other advantages.Some series of aluminum alloys have been applied to automobile structural parts and covers such as engine covers,fenders,bumpers,etc.,but the forming of aluminum al-loy at room temperature has defects such as poor formability,easy cracking,easy rebound and so on,especially for 7xxx series of high-strength aluminum alloys,the defects are particularly serious.The new process of high-strength aluminum alloy solid solution hot stamping quenching aging integrated forming is a new process developed to solve the problems of poor plasticity,easy cracking,large spring back and low dimensional accuracy of high-strength aluminum alloy sheet during cold stamping.This process associates the hot forming technology with the heat treatment system,and quickly transfers the sheet metal after obtaining single-phase solid solution through solution treatment to the mold for forming,the solid solution with supersaturated solute atoms and vacancies is obtained by holding pressure in the mold and rapid quenching process.Finally,the strength is improved by aging system.The key influencing steps are whether to obtain single-phase solid solution,realize rapid quenching,aging treatment and the influence of heat transfer during sheet metal transfer between processes.Combined with the existing research results of aluminum alloy hot stamping process at home and abroad,this paper introduced the development status of aluminum alloy sheet hot stamping process,focused on combing the re-search status of high-strength aluminum alloy sheet hot stamping process hot forming and in-die quenching(HFQ)in numerical simu-lation technology,equipment,process key technology,and looked forward to the follow-up research direction for its technical difficul-ties,so as to provide reference for aluminum alloy sheet stamping.Through the summary of domestic and foreign literature,it was found that in the numerical simulation of hot stamping process,because HFQ process involved many factors such as stamping process parameters,temperature,solution aging,and there were mutual coupling effects between the parameters,it was difficult to realize the simulation of traditional finite element simulation method in the meso scale,and the establishment of constitutive model at the meso level was the key to realize accurate simulation.At present,the establishment of the meso constitutive model for the hot stamping pro-cess of high-strength aluminum alloy was not perfect.Based on the crystal plastic constitutive model of TA 15 biphasic titanium alloy es-tablished in the early stage,the idea of crystal plastic finite element constitutive model for hot stamping process was put forward,which expanded the idea of meso scale simulation of high-strength aluminum alloy hot stamping process.Later,it could be combined with cellular automata or Monte Carlo method,taking into account the organization evolution process in the hot stamping process,the hot stamping process could be adjusted according to the process parameters to achieve the purpose of integrated forming simulation of shape control,property control and organization control.In terms of the key technologies of hot stamping process,the current problem was that the solution time and aging time did not match the pace of hot stamping.Therefore,according to the target requirements of how to achieve rapid solution and short-term aging,it could be achieved by improving the heating method,increasing the heating tem-perature,and innovating the double aging system,such as using conductive heating,radiation heating,spraying lubricant on the sur-face of the sheet,etc.In terms of stamping equipment,with the implementation of national six standards and the development of pro-cessing technology,combined with the principles and key technologies of hot stamping process,the problems of mismatch between sol-id solution,aging time and stamping rhythm in hot stamping process could be solved by developing new heating equipment,heating mode,intelligent equipment between various links,etc.,such as the use of industrial robots Intelligent manipulator and other methods to solve the problem of temperature drop in the transfer process of sheet metal.It could be seen that the three aspects of numerical simu-lation,key technology and stamping equipment affect and restrict each other in the process of hot stamping process research.There-fore,comprehensive consideration was needed in the process of formulating the hot stamping process of high-strength aluminum alloy automotive parts.Under the given conditions of the equipment,the process optimization was completed through numerical simulation to save costs and further complete the realization of hot stamping process.
aluminum alloyhot stamping processlightweightsheetsolid solutionaging process
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