Abstract: A stainless steel material for a fuel cell, used for a fuel cell or a cartridge for the fuel cell, having a magnetic permeability of 1.000 to 2.500, and forming a layer having a value of chromium atomic %/iron atomic % of not less than 3.0 in the most surface thereof, and/or the layer of thickness of not less than 12 nm calculated as SiO2 having an oxygen atomic % of not less than 20%. Even when brought into contact with the content solution exhibiting acidity of the fuel cell, the stainless steel material reliably suppresses the elution of metal ions thereof.

Abstract: A coil spring for fuel cells, used for a fuel cell or a cartridge for the fuel cell, comprising an austenite type stainless steel without any nickel layer formed on the surface thereof, and having a cationic index I of not more than 60 as expressed by the following formula (1), I=A+2B+3C??(1) wherein A, B and C represent, respectively, a concentration (ppb) of monovalent metal ions, a concentration (ppb) of metal ions which are neither monovalent nor trivalent, and a concentration (ppb) of trivalent metal ions per the coil spring in a methanol solution of when the coil spring is dipped in the methanol solution (containing 1% of water+4000 ppm of formic acid) and preserved therein at 60° C. for one week. Even when brought into contact with the content solution exhibiting acidity of the fuel cell, the coil spring reliably suppresses the elution of metal ions thereof.

Abstract: A stainless steel material for a fuel cell, used for a fuel cell or a cartridge for the fuel cell, having a magnetic permeability of 1.000 to 2.500, and forming a layer having a value of chromium atomic %/iron atomic % of not less than 3.0 in the most surface thereof, and/or the layer of thickness of not less than 12 nm calculated as SiO2 having an oxygen atomic % of not less than 20%. Even when brought into contact with the content solution exhibiting acidity of the fuel cell, the stainless steel material reliably suppresses the elution of metal ions thereof.