Method for manufacturing a metallic functional part delimiting a porous filtering medium, using an additive manufacturing method, and obtained functional part

A manufacturing method enabling the obtainment of a functional part essentially formed in a metallic material, all or part of the functional part delimiting a filtering medium permeable to a fluid and delimiting first and second main faces for a circulation of the gas through the filtering medium between the first and second main faces, the manufacturing method comprising a main phase consisting of an additive manufacturing method in successive passes from a support tray, each pass comprising the deposition of at least one layer of the metallic material, the deposited material adhering to the metallic material of at least one layer deposited before, the deposition of the metallic material at the level of each layer being controlled at each pass such that the stack of the metallic material deposited during the successive passes constitutes the functional part, whose filtering medium comprises a coalescent network of connecting strands interconnected according to a three-dimensional spatial distribution between the first and second main faces, the connecting strands of the network delimiting therebetween pores spatially distributed within the filtering medium in three dimensions between the first and second main faces;

• wherein each pass comprises a step of depositing at least one powder layer formed in the metallic material and then a step of selective melting of the powder deposited before through a local energy input by the action of a laser beam, the selective melting of the metallic material being controlled using a pre-established computer database, which computer database controls at each pass, by a computer program controlling a spatial displacement of the laser beam relative to the metallic material powder deposited before, at least one of the parameter selected amongst:
• a relative path between the laser beam and the powder deposited before, a displacement velocity corresponding to a relative velocity between the laser beam and the powder deposited before, a laser beam power, a laser beam power density;
• wherein at each selective melting step, the path followed by the laser beam comprises displacement vectors where the displacement vectors are spatially offset in pairs according to an offset value and wherein the porosity rate of the pores within the filtering medium is adjusted, for a given laser beam power and a given layer thickness, by adapting the offset value, the porosity rate increasing as the offset value increases;
• and
• wherein at each selective melting step, the porosity rate of the pores within the filtering medium is adjusted, for a given laser beam power and a given layer thickness, by adapting the displacement velocity, the porosity rate increasing above a lower threshold of the displacement velocity, as the displacement velocity increases.