Abstract: A turbine housing of a turbocharger made of ductile iron and a self-diffused Ni--Cr alloy including C, B and Si fusion-coated to at least the surface of the main portion of the turbine housing. The turbine housing is not likely to be oxidized and deteriorated, and it has durability.

Abstract: Welding between a rotor and shaft is accomplished by first placing the shaft within a movable holder of a pressure device. The rotor is then placed in the lower or stationary holder of the pressure device. Each holder is an electrode that can electrify the shaft and rotor. The stationary holder is a cup or container which has inside the cup, a low melting point alloy which conducts electricity from the lower electrode to the rotor to prevent concentration of electricity. Welding is finished by lowering the shaft onto the rotor which is in the cup which is heated to liquefy the low melting point alloy. As the shaft and rotor are pressed together, current is passed through each by the electrodes. The junction of the shaft and rotor are melted and thus joined. After cooling, any of the low melting point metal which remains on the rotor is removed by inserting the rotor in boiling water.