A method of producing a welded assembly from a first metal part and a second metal part includes bringing the first metal part and the second metal part into contact with one another at a joint region while providing a flash ring separator adjacent the joint region configured to intercept and separate flash. After heating the joint region, the first and second metal parts are forced together to join the first metal part to the second metal part, extruding metal flash from the joint region. The extruded flash impinges on the flash ring separator, forming a flash ring having at least one indentation. During subsequent machining of the welded assembly to remove the flash ring, the flash ring may fragment at the indentation, so that it does not cause damage by becoming hung around the assembly.