Investigation On The Influence Of Mechanical Clinch To The Fatigue Characteristics Of Steel-aluminum Connection

The rapid development of automobile industry in recent years has led to the problem of energy and the environmental issues has becoming increasingly serious. As an important technical means to alleviate these problems. Automotive lightweight getting more and more people’s attention.The method for vehicle body reducing can be reached from the flowing three aspects, using new materials, optimization of body structure and using new manufacturing process. Now the research in these three aspects has already reach a high level, but considering that vehicles are mass productions of industrial products, we must take the cost and sustainability in consider, it cannot be ignored. And, to an extent it has led to a lot of restrictions for the use of new materials. The study for the optimization of the automobile body now is already very mature and developed. It is not realistic to reduce lots of body weight from the body structure optimization. So this study is star from the use of new manufacturing process, the traditional body connection technology have such-and-such shortcomings facing with the connection of new light materials. such as spot welding defects of solder joints is not stable, easy to generate impurity; the disadvantages of riveting process is poor appearance, riveting efficiency is relatively low; bonding process in high temperature curing prone to deformation. And in the high strength steel especially ultra-high strength steel and aluminum alloy heterologous metal connection and joint quality is unsatisfactory, cannot meet the actual requirement.So we came to the idea that using traditional self-piercing riveting technology and hot forming process combination for high strength steel and Aluminum Alloy with the connection between them. Our study begin with such aspects.At first we should make heat treatment of high strength steel, we matched different result from different heat treatment and different cooling mode for the high strength steel. We found that use the "salt" batch heating, quenching oil for batch cooling by heat treatment results less oxidation, material deformation smaller, the results of the heat treatment is relatively stable.After heat treatment of high strength steel material we make some static and fatigue test, matched high strength steel which was not with heat treatment process. We want to know that if the high strength steel after heat treatment process also can meet the needs.With the work for design riveting mound, we do some fatigue test with the heat treatment of high-strength steel and aluminum alloy materials after riveting forming test. Of riveting joint effect on quality of high strength steel and aluminum alloy material is arranged in different ways and different forming parameters, from the quality of riveted joints shape of riveted joints to determine the optimal material layout and the optimal forming parameters, under the optimal process parameters obtained a number of dissimilar metal without rivets riveting components, used for the next research.The static and fatigue tests were carried out on the obtained rivet joints, and the S-N curves of the riveting joints were obtained by the group fatigue test method, with the fatigue properties of the joints which has been studied. We can make a decision with the obtained test results whether the resulting riveting joint can meet the actual needs or not.