Investigation of the effect of soaking time on hardness and corrosion resistance of Fe-Cr-Mn alloy during deep cryogenic treatment.

The Fe-Cr-Mn alloy is a new alloy that can replace the Fe-Cr-Ni stainless steel, where the manganese element replaces the nickel, which is relatively expensive. There is still little research on improving the mechanical properties of the Fe-Cr-Mn alloy by the deep cryogenic treatment (DCT) process. This research evaluates the effect of DCT soaking time on the microstructure, hardness, and corrosion resistance of Fe-14Cr-9,5Mn alloy. The DCT process was carried out in a cryogenic chamber at a time variation of 5, 10, 15, 20, and 25 minutes. These analyses were performed using an optical and scanning electron microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Vickers hardness tester, and weight loss corrosion testing. The microstructure test results showed that the Fe-Cr-Mn alloy has ferrite and pearlite microstructure. The ferrite grain size gets smaller, with the longer the holding time of the deep cryogenic treatment process. The hardness test results showed that raw material has a hardness of 302.8 kg/mm2. While the highest hardness value of 340.6 kg/mm2 occurs on 25 minutes holding time, the higher the soaking time, the higher the alloy hardness. The corrosion resistance of Fe-Cr-Mn alloy is included in the outstanding category, with a corrosion rate of 0.026 mm/yr. The cryogenically treated specimens proved the corrosion resistance until 0.022mm/yr on 25 minutes holding time; the longer the soaking time, the lower the corrosion rate. [ABSTRACT FROM AUTHOR]