Method for welding two steel sheets of thickness 0.10 to 6.0 mm and having the following composition in weight percent: * 0.005 % ≤ C ≤ 0.3 %; * 0.2 % ≤ Mn ≤ 2.0 %; * traces ≤ Si ≤ 1.0 %; * traces ≤ S ≤ 0.01 %; * traces ≤ P ≤ 0.04 %; * 10.5 % ≤ Cr ≤ 17.0 %; preferably 10.5 % ≤ Cr ≤ 14.0 %; * traces ≤ Ni ≤ 4.0 %; * traces ≤ Mo ≤ 2.0%; * Mo + 2 × W ≤ 2.0 %; * traces ≤ Cu ≤ 3 %; preferably traces ≤ Cu ≤ 0.5 %; * traces ≤ Ti ≤ 0.5 %; * traces ≤ Al ≤ 0.2 %; * traces ≤ O ≤ 0.04 %; * 0.05% ≤ Nb ≤ 1.0 %; * 0.05% ≤ Nb + Ta ≤ 1.0 %; * 0.25 % ≤ (Nb + Ta)/(C + N) ≤ 8; * traces ≤ V ≤ 0.3 %; * traces ≤ Co ≤ 0.5 %; * traces ≤ Cu + Ni + Co ≤ 5.0 %; * traces ≤ Sn ≤ 0.05 %; * traces ≤ B ≤ 0.1 %; * traces ≤ Zr ≤ 0.5 %; * Ti + V + Zr ≤ 0.5 %; * traces ≤ H ≤ 5 ppm, preferably traces ≤ H ≤ 1 ppm; * traces ≤ N ≤ 0.2 %; * (Mn + Ni) ≥ (Cr -10,3 - 80 × [(C + N) 2]); * traces ≤ Ca ≤ 0.002 %; * traces ≤ rare earths and/or Y ≤ 0.06 %; * the remainder being iron and impurities resulting from steelmaking; - the start temperature (Ms) of martensitic transformation of the sheet being ≥ 200 °C; - the finish temperature (Mf) of martensitic transformation of the sheet being ≥ -50 °C; - the microstructure of the sheet containing no more than a 0.5 % volume fraction of carbides, and no more than a volume fraction of 20 % residual ferrite, the remainder being martensite; characterized in that it comprises the following steps, (e) being the thickness of each of said sheets or of the thinnest amongst them: - A first welding step lasting a time (t) in ms: * for thicknesses (e) of 0.10 to 0.50 mm: t = 40 × e + 36 ± 10 % * for thicknesses (e) of 0.51 to 1.50 mm: t = 124 × e − 13 ± 10 % * for thicknesses (e) of 1.51 to 6.0 mm: t = 12 × e + 47 ± 10 % and with a clamping force in daN: * for thicknesses (e) of 0.10 to 1.50 mm: F = 250 × e + 90 ± 10 % * for thicknesses (e) of 1.51 mm to 6.0 mm: F = 180 × e + 150 ± 10 % a current being applied at this step between the welding electrodes, having an intensity of between 80 and 100 % the maximum permissible intensity corresponding to expulsion of molten metal; - A second step at which the pressure of the electrodes is maintained and the current intensity is set at between zero and 1 kA for a minimum time tf ≥ 34 × e + 2 ms; - And a third step at which the passing of current is resumed at an intensity of 3.5 kA to 4.5 kA, for a time of at least 755 ms, to apply heat treatment to the weld zone, the sum of the times of said first, second and third steps being no more than 2 s, preferably no more than 1.5 s, better still no more than 1 s. * 0.005 % ≤ C ≤ 0.3 %; * 0.2 % ≤ Mn ≤ 2.0 %; * traces ≤ Si ≤ 1.0 %; * traces ≤ S ≤ 0.01 %; * traces ≤ P ≤ 0.04 %; * 10.5 % ≤ Cr ≤ 17.0 %; preferably 10.5 % ≤ Cr ≤ 14.0 %; * traces ≤ Ni ≤ 4.0 %; * traces ≤ Mo ≤ 2.0%; * Mo + 2 × W ≤ 2.0 %; * traces ≤ Cu ≤ 3 %; preferably traces ≤ Cu ≤ 0.5 %; * traces ≤ Ti ≤ 0.5 %; * traces ≤ Al ≤ 0.2 %; * traces ≤ O ≤ 0.04 %; * 0.05% ≤ Nb ≤ 1.0 %; * 0.05% ≤ Nb + Ta ≤ 1.0 %; * 0.25 % ≤ (Nb + Ta)/(C + N) ≤ 8; * traces ≤ V ≤ 0.3 %; * traces ≤ Co ≤ 0.5 %; * traces ≤ Cu + Ni + Co ≤ 5.0 %; * traces ≤ Sn ≤ 0.05 %; * traces ≤ B ≤ 0.1 %; * traces ≤ Zr ≤ 0.5 %; * Ti + V + Zr ≤ 0.5 %; * traces ≤ H ≤ 5 ppm, preferably traces ≤ H ≤ 1 ppm; * traces ≤ N ≤ 0.2 %; * (Mn + Ni) ≥ (Cr -10,3 - 80 × [(C + N) 2]); * traces ≤ Ca ≤ 0.002 %; * traces ≤ rare earths and/or Y ≤ 0.06 %; * the remainder being iron and impurities resulting from steelmaking; - the start temperature (Ms) of martensitic transformation of the sheet being ≥ 200 °C; - the finish temperature (Mf) of martensitic transformation of the sheet being ≥ -50 °C; - the microstructure of the sheet containing no more than a 0.5 % volume fraction of carbides, and no more than a volume fraction of 20 % residual ferrite, the remainder being martensite; - A first welding step lasting a time (t) in ms: - A second step at which the pressure of the electrodes is maintained and the current intensity is set at between zero and 1 kA for a minimum time tf ≥ 34 × e + 2 ms; - And a third step at which the passing of current is resumed at an intensity of 3.5 kA to 4.5 kA, for a time of at least 755 ms, to apply heat treatment to the weld zone,