Method for manufacturing an austenitic stainless steel workpiece having a difference in density between its core and its surface, and having a nitrogen content greater than or equal to 0.1% by weight with optionally a carbon content greater than or equal to 0.1% by weight and having a nickel content less than or equal to 0.5% by weight, the method comprising the following steps carried out in a controlled atmosphere: 1) Providing a sintered alloy with an austenitic structure or providing a powder and sintering the powder to form said sintered alloy, the sintered alloy having a nitrogen content greater than or equal to 0.1% by weight, optionally with a carbon content greater than or equal to 0.1% by weight and having a nickel content less than or equal to 0.5%, 2) Denitriding and/or decarburising the sintered alloy to transform said austenitic structure into a ferritic structure or ferrite + austenite two-phase structure on a surface layer of the alloy, step 2) being carried out by performing one or more of the following actions: adjusting the temperature, adjusting the partial pressure of a nitrogen carrier gas of the atmosphere, adjusting the partial pressure of a carbon carrier gas of the atmosphere, to denitrify and/or decarburise the surface layer, 3) Denitriding and/or decarburising the sintered alloy to transform the ferritic or ferrite + austenite two-phase structure obtained in step 2) into said austenitic structure and, after cooling, forming the workpiece which, on the layer subjected to the transformations in steps 2) and 3), has a density higher than that of the core of the workpiece, step 3) being carried out by performing one or more of the following actions: adjusting the temperature, adjusting the partial pressure of a nitrogen carrier gas of the atmosphere, adjusting the partial pressure of a carbon carrier gas of the atmosphere, to denitrify and/or decarburise the surface layer. 1) Providing a sintered alloy with an austenitic structure or providing a powder and sintering the powder to form said sintered alloy, the sintered alloy having a nitrogen content greater than or equal to 0.1% by weight, optionally with a carbon content greater than or equal to 0.1% by weight and having a nickel content less than or equal to 0.5%, 2) Denitriding and/or decarburising the sintered alloy to transform said austenitic structure into a ferritic structure or ferrite + austenite two-phase structure on a surface layer of the alloy, step 2) being carried out by performing one or more of the following actions: adjusting the temperature, adjusting the partial pressure of a nitrogen carrier gas of the atmosphere, adjusting the partial pressure of a carbon carrier gas of the atmosphere, to denitrify and/or decarburise the surface layer, 3) Denitriding and/or decarburising the sintered alloy to transform the ferritic or ferrite + austenite two-phase structure obtained in step 2) into said austenitic structure and, after cooling, forming the workpiece which, on the layer subjected to the transformations in steps 2) and 3), has a density higher than that of the core of the workpiece, step 3) being carried out by performing one or more of the following actions: adjusting the temperature, adjusting the partial pressure of a nitrogen carrier gas of the atmosphere, adjusting the partial pressure of a carbon carrier gas of the atmosphere, to denitrify and/or decarburise the surface layer.