Abstract: This application is a continuation-in-part of application Ser. No. 07/218695, filed Aug. 8, 1988. This invention describes a series of Fe-Mn-Al-C based corrosion resistance alloys. It also describes how to obtain such alloys which has comparable good corrosion resistance in many environments to conventional stainless steel as 304 and 430. The correlation of chemical compositions among the manganese, aluminum, carbon and other minor elements ae discussed. Therefore they are made to be practical and more definitive. According to more advanced understanding in overall of the Fe-Mn-Al-C based alloys that are included in this invention have to be surface treated and/or pickled, passivated by the methods included in this invention. After the surface treatments, the final products will have an obviously comparable depleted manganese and/or higher chromium on the alloy surface and will have better corrosion resistance than the conventional Fe-Mn-Al-C and Fe-Mn-Al-C-Cr based alloys.