FeCrMn may possibly be used in conjunction with aqueous blankets or cooants in a fusion device. Therefore, standard chemical immersion (modified Strauss) tests were conducted to characterize the effects of compositional modifications on the thermal sensitization behavior of these steels. A good correlation among weight losses, intergranular corrosion, and cracking was found. The most effective means of decreasing their susceptibility was through reduction of the carbon concentration of these steels to 0.1%, but the sensitization resistance of FeCrMn0.1 C compositions was still inferior to type 304L and other similar stainless steels. Alloying additions that form stable carbides did not have a very significant influence on the sensitization behavior.