The conjugation of , and in the Fe-Mn-S ternary system with up to 4% of manganese in iron phase, was investigated as the first approach to understand kinetics of sulfide formation in steel, and the compositions of all phases were determined in the temperature range from 670•Ž to 1500•Ž.

A four-year atmospheric exposure test was performed on steel with a Zn30 mass%Al thermal-sprayed coating using an accelerated atmospheric exposure test, and then the atmospheric corrosion properties were evaluated. X-ray diffraction results showed that the corrosion products formed on the coating owing to the accelerated atmospheric exposure test were the same as those formed in a typical atmospheric exposure test. The corrosion weight loss of the thermally sprayed coatings in the accelerated atmospheric exposure test was promoted by approximately 1.5 to 2.0 times compared to the atmospheric exposure test.

Three conjugations oj [Liquid-Iron-(Mn,Fe)S] , [Liquid-Iron-(Fe, Mn)S] and [ Iron-(Mn,Fe)S-(Fe, Mn)S] ill the Fe-Mn-S temary-!)istem cOlltaining liP to 4~o oj mallganese in iroll phase, were investigated as the first apj"oach to understand the kinetics oj sulfide jormation in steel, and the compositions oj all phases were determined in the temperature range oj 670° to 1 500°C. The results are summarized as jollows: (1) The three-phase conjugation [Liquid-Iron-(Mn, Fe)S] was observed in the temperature range oj I 004° to J 50(f'C. (2) No evidence wasjoundjor the intersection oj the eutectic line with a miscibility gap jmposed by I Ventmp. (3) The solubility q(sulfur in iron abruptfy decreased at 1 37 /°Cjrom 0. 12% to 0.(}5 % with the (j I transformation oj iron. (4) As a result qf Ihe peri tecto-eutectic reaction , jour phases oj liquid, iron, (Mn.Fe)S and (Fe, Mn)S coexisted at 1 (}04°C. (5) B elow the peritecto-eutectic temperature, both three-phase conjugatioll oj [Liquid-Iron-(Fe,M n)S] and [Iron-(Mn,Fe)S-(Fe,Mn)S] were stable. The jormer met the Fe-FeS binary at 988"C, which is the eutectic fem/J era ture.

T he effect of carbon on the eutectic conjugation of liquid, iron crystal and (Mn,Fe)S in the Fe-Mn-S system was investigated in the range from the maximum temperature rif eutectic line to peritecto-eutectic temperature. The effects of carbon and silicon on the composition of (Mn,Fe)S in [iron-(Mn ,Fe)S] conjugation was also studied from 1 450°C to 950°C. The results were as fo llows : (1) E utectic temperature was lowered and the eutectic line was shifted towards the iron corner in the Fe-M n-S diagram, as the carbon content of iron crystal increased. (2) T he addition of carbon increased the manganese content of the iron crystal and (Mn,Fe)S in the eutectic conjugation, and decreased the sulfur content of the former. As the temperature was decreased, both the tendencies of (1) and (2) gradually diminished and were not recognized at all below 1 250Co. (3) When the carbon content rif the iron crystal exceeded 0.25% , the four-phase conjugation [liquid iron-liquid sulfide-iron crystal-(Mn,Fe)S] resulted from the intersection of the eutectic line with the miscibility gap. (4) T he lower the temp erature alld the higher the manganese contellt ill the iron matrix, the higher was the manganese content rif (M n,Fe)S in [iron-(Mn,Fe)S] cOIVugation. The composition rif (M n,Fe)S was hardly affected by carbon and silicon contents in the iron matrix.

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