Abstract: An insert for connecting a part made from a steel containing 12-14% by weight of manganese to at least one carbon steel part, said insert being made from an austenitic-ferritic alloy having the following chemical composition (in % by weight):______________________________________ Carbon 0.025-0.035% Manganese 6-11% Silicon 0.5-1.5% Nickel 5-8% Chromium 17.5-20% Molybdenum <0.5% Nitrogen 0.12-0.20% Phosphorus and sulfur .ltoreq.0.030% ______________________________________and the delta ferrite content of which (in percent by volume) as measured by micrographic counting ranges between about 5% and 15%.