Effect of the Segregation of Different FE-Phases on the Susceptibility to Cracks of AL-Cylinder Heads

摘要

Suppliers of the motor-car industry have to confront more and more with the fact that the main goal of the motor factories is to produce lighter and more highly efficient components. One of the most important part of the car - or the most important - is the cylinder-head. Higher efficiency and smaller weight are principle in this field, too. However, one of the largest disadvantage of thin walls is the susceptibility to cracks. Hydro Aluminium Gyor Ltd. had to confront with this phenomenon that required a better quality in the cylinder-head production. To meet the high strength requirements, continuous technology-development and production discipline are necessary. A good information background was assured for our developments by the knowledge base and equipment accumulated in the R&D center that belongs to the concern. During our experiments we lay great emphasis during our experiments on the quality of the melt and the cooling rate in the die. In the experiments, carried out with our Al suppliers, we determined the parameters that give yield the best quality Al die. This is essential for the high strength properties and to reduce the susceptibility to cracks. Another aim of the tests was to find the importance of the cooling schedule. With the support of our R&D center, we succeeded in determining the optimum cooling parameters. Thermo-shock tests were very profitable to check the efficiency of the changes. 1. Appearance of the problems, basic conditions: It was necessary to make further experiments, because during the year 2003 two new cylinder-heads arrived at our company and we had several problems during the manufacturing.