YUHONG GROUP - About N08367

SSC-6MO(UNS N08367) is A super austenite containing 6% molybdenum with a density of 8.02 g/cm ³, conforming to ASTM.A 240, B688 ASM.SA 240, SB688
It offers excellent corrosion resistance to chloride pitting, intergranular corrosion and stress corrosion cracking compared to standard 300 series and duplex stainless steels. The 8367 is a cost-effective alternative to expensive nickel alloys where excellent corrosion resistance, strength, ease of machining and welding are required. Equivalent to alloy AL6XN®. The composition of high nickel (24%) and high molybdenum (6.5%) is conducive to the resistance of 8367 to stress corrosion cracking of chloride, and the composition of molybdenum is resistant to the pitting of chloride. The high content of chromium (21%) and nitrogen (0.22%) contributes to the excellent corrosion resistance of the alloy. Because of the high nitrogen content, 8367 has strong tensile properties compared to ordinary austenitic stainless steel. The 8367's flexibility and malleability make it easy to process. Compared to other super duplex stainless steels and the relatively corrosion-resistant ferritic stainless steels, 8367 is easier to weld and form.
The most common cause of corrosion in stainless steel is local chloride corrosion, especially pitting corrosion, intergranular corrosion and stress corrosion cracking. 8367 is an upgraded version of austenitic stainless steels such as 316L, 317L and 904L.
The pitting resistance of austenitic stainless steel is directly related to its composition, because chromium, molybdenum and nitrogen occupy a certain proportion. Pitting resistance value (PREN) is used to measure the corrosion resistance of the alloy - the higher the PREN value, the better the pitting resistance.
The formula for PREN is: PREN = % chromium + 3.3 x molybdenum + 30 x nitrogen
The PREN of 304 is 20, the PREN of 316L is 25, the PREn of 904L is 37, and the PREN of 8367 is 48.
The high molybdenum and nitrogen content of 8367 has a favorable effect in the environment of chlorine, oxidation and acid solutions, and its intergranular corrosion resistance in seawater is better than that of 316L, 2205 and 904L.
The critical intergranular corrosion temperature test (CCCT) is often used to compare the intergranular corrosion resistance of different alloys.
In 10% ferric chloride solution, the temperature at which 316L begins to undergo intergranular corrosion is 27 degrees, alloy 825 is 27 degrees, 904L is 68 degrees, and 8367 can reach 95 degrees.
Chloride stress corrosion is the most serious type of local corrosion, and high temperature and low PH value will increase the possibility of chloride stress corrosion. It has been determined that if the nickel content of the alloy is increased by more than 12% and the molybdenum content is increased by more than 3%, its resistance to chloride stress corrosion cracking will be improved. The 8367 performs better than ordinary 300 series stainless steels and some super duplex stainless steels. The 8367 has excellent resistance to chloride stress and corrosion up to 121°C. When the content of nitrogen chloride decreases, the critical temperature of stress corrosion cracking induced by chloride increases accordingly. When the temperature is higher than 121°C, use 8367 with caution.