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.

Abstract: Carbon steels and other hot-and cold-workable ferrous alloys generally have poor damping capacity as compared to that cast iron (gray cast iron, malleable cast iron and ductile cast iron). This is because the graphite in cast irons helps to absorb the damping force and depresses the damping wave. But cast iron can not be rolled into strip or sheet.By controlling the correlated concentrations of manganese, aluminum and carbon, Fe-Mn-Al-C based alloys are made to be .alpha.+.gamma. two-phase alloy steel with different .alpha. and .gamma. volume fractions. With particular ferrite volumes, workable Fe-Mn-Al-C based alloys have equivalent and better damping capacity than that of cast irons especially in the high frequency side. Such alloys suppress the vibration noise that comes from machine rooms, motors, air conditioners, and etc. Chromium and other minor amount of elements can be added to this alloy system to improve the corrosion resistance.

Abstract: This invention describes the melting of Fe-Mn-Al Alloys and includes production methods such as non-continuous casting, continuous casting, hot forging, hot rolling, cold rolling, surface finishing, and heat treating. Products produced using one or more of the above said methods include case ingot, billet, bloom, slab, cast piece, hot-rolled plate, hot-rolled coil, bar, rod, cold-rolled strip and sheet, and hot-forged piece. The said alloys consist principally of by weight 10 to 35 percent Mn, 4 to 12 percent Al, 0 to 12 percent Cr, 0.01 to 1.4 percent C, 0.3-1.5 Mo, 0.1-1% S, a small amount of Cu, Nb, V, CO, Ti, B, N, Zr, Hf, Ta, Sc, W, and Ni, and the balanced Fe.