Research on the connection technology of TiAl alloy turbine in diesel engine turbocharger

Turbine shaft is one of key parts of turbocharger. Nowadays, the most common way to produce turbine shaft is to connect nickel-based high-temperature alloy K418 turbine and 42CrMo steel shaft by friction welding. Because the density of TiAl alloy is less than half of nickel-based high-temperature alloy K418, the weight of turbine made from TiAl can be reduced more than half. Therefore, the transient response can be improved efficiently and some environmental protection problems can be solved at the same time. However, TiAl alloy is a sort of intermetallic compound and it is impossible to connect it with alloy steel shaft by friction welding based on the analysis of material molecule configuration theory. In this paper, three sections connecting method designed for mass production is studied. A high quality and good reliability connection of TiAl turbine and steel shaft is obtained. The goals of easy operation, convenience and high efficiency are achieved.