TYPE 316 STAINLESS STEEL INCONEL AND HAYNES ALLOY NO.25 NATURAL-CIRCULATION BOILING-POTASSIUM CORROSION TEST LOOPS

摘要

An investigation was undertaken to determine the compatibility of conventional nickel-, iron-, and cobalt-base high-temperature alloys with boiling potassium. The tests were designed to obtain quantitative information on the dissolution of the container alloys by condensing potassium and the subsequent deposition of solute in a subcooled liquid region of the test device.nStudies were conducted in natural-circulation loops, two of which were fabricated from type 316 stainless steel, two from Haynes alloy No. 25, and one from Inconel. Each of the alloys was operated at a maximum boiler-condenser temperature of 870°C for 1500 to 3000 hr, and the Haynes alloy No. 25 was also tested for 3000 hr at 980°C. The potassium condensing rates at the two temperatures were 170 to 180 and 300 g/min, respectively.nAt 870°C type 316 stainless steel and Haynes alloy No. 25 exhibited comparable resistance to attack by boiling potassium, while Inconel showed greater deterioration.nCarbon was transferred from the condensing region to the subcooled liquid region in all the loop tests. Attend ant with this, the elongation of the material decreased and the tensile strength increased. No evidence of preferential leaching of major metallic constituents of these alloys was detected by electron microprobe analysis of the condenser surfaces. However, limited mass transfer from the hot region to the cold region was noted.