Snecma

Safran Aircraft Engines

Patrick Philipson

Laurent Ferrer

A method of fabricating a stainless martensitic steel includes a step of electroslag remelting of an ingot of the steel then a step of cooling the ingot. Before the skin temperature of the ingot falls below the martensitic transformation temperature Ms of the steel, the ingot from electroslag remelting is placed in a furnace with an initial temperature Tthat is then higher than the pearlitic transformation completion temperature on cooling, Ar, of the steel, the ingot undergoing a homogenization treatment in the furnace for at least a holding time t after which the temperature of the coldest point of the ingot has reached a homogenization temperature T, the holding time t being equal to at least one hour, with the homogenization temperature T being in the range approximately 900&#xb0; C. to the burning temperature of the steel.

Homogenization of martensitic stainless steel after remelting under a layer of slag

A method fabricating a stainless martensitic steel, including electroslag remelting then cooling an ingot of the steel, then at least one austenitic thermal cycle heating the ingot above its austenitic temperature followed by a cooling. During each cooling: if the cooling is not followed by an austenitic thermal cycle, holding the ingot at a holding temperature included in the ferritic-pearlitic transformation nose for a hold time longer than sufficient for transforming the austenite into a ferritic-pearlitic structure in the ingot as completely as possible at the holding temperature; if the cooling is followed by an austenitic thermal cycle, before its minimum temperature falls below the martensitic transformation start temperature, the ingot is either held throughout the period between the two austenitic thermal cycles at a temperature above the austenitic transformation completion temperature on heating, or held at the holding temperature included in the ferritic-pearlitic transformation nose.

Heat treatment of martensitic stainless steel after remelting under a layer of slag

The invention relates to a method of fabricating a stainless martensitic steel, comprising a step of electroslag remelting of an ingot of said steel then a step of cooling said ingot. Before the electroslag remelting step, the ingot undergoes vacuum degassing for a time that is sufficient to obtain a hydrogen content in the ingot of less than 3 ppm.

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Bois-le-Roi, France

Patrick Philipson