A method of joining parts of the wastegate assembly, and a wastegate assembly includes an arm defining a hole. The wastegate assembly also includes a shaft. The shaft includes a first end disposed inside the hole of the arm. The shaft includes an outer surface defining a groove disposed inside the hole of the arm. The arm and the first end of the shaft are welded together to form a joint having a joint root region disposed adjacent to the groove.A turbocharger includes a compressor, a turbine and a rotating assembly driven by exhaust gas. The rotating assembly has a turbine wheel disposed inside the turbine and a compressor wheel disposed inside the compressor. The turbocharger further includes the wastegate assembly described above, and the wastegate assembly defines an opening configured to selectively redirect at least a portion of the exhaust gas to bypass the turbine wheel.