Abstract: The object of the invention is to provide simple and cost-effective, internal rupture protection for the axial turbine of an exhaust-gas turbocharger. At the same time, the functional reliability of the exhaust-gas turbocharger is to be increased. According to the invention, this is achieved in that the rupture-protection ring (8) is designed as an integral, essentially radially extending, part of the gas-inlet-side wall (5) of the gas-outlet casing (2) and is connected to the gas-inlet casing (1) either directly or via an axial extension piece (6) arranged upstream.

Abstract: Blanks or structural components of steel are joined to those of an aluminum alloy (a) or titanium alloy (b) by friction-welding with insertion of at least one transition layer of a ductile subgroup metal, in particular by applying, according to (a), a pure nickel layer to the steel by friction-welding and joining the surface of the nickel layer, after weld bead removal, to the aluminum alloy by friction-welding. According to (b), a copper layer is applied to the steel by friction-welding and a vanadium layer is applied to the titanium alloy by friction-welding. The copper and vanadium surfaces are, after weld bead removal, then joined to one another by friction-welding. In the case of steel which tends to form martensitic zones, a layer of austenitic steel is applied by friction-welding before the application of the copper layer. The process is especially suitable for joining the turbine wheel and shaft or fixing component for the shaft of a turbocharger.