Abstract
Suction rolls in modern paper machines must meet the demands of performing under cyclic loading in increasingly corrosive environments. Thus, evaluating corrosion-fatigue behavior is an essential element in the development of alloys for use in suction-roll shells. For this reason, we have been continuously evaluating the corrosion-fatigue behavior of commercial and potential suction-roll alloys for the past 28 years. This paper reviews the highlights of those evaluations, emphasizing the results of recent studies.
Corrosion-fatigue tests have been performed on specimens taken from production centrifugal castings of 4 types of alloys -- (1) bronze, (2) martensitic stainless steels, (3) austenitic stainless steels, and (4) duplex stainless steels. Fatigue curves have been developed out to 109 cycles to failure using R. R. Moore rotating bending fatigue machines. Test environments are simulated white water solutions with 800 ppm sulfate, 20 to 1000 ppm chloride, 0 to 40 ppm thiosulfate, and a pH of 3.5. Changing the cyclic frequency (350 to 3000 cpm) has a significant effect on corrosion fatigue life. Also, periodic surface cleaning to simulate service conditions is an important factor, especially in more corrosive environments. The implications of the corrosion-fatigue results on potential service performance, current material evaluations, and possible directions for future work are discussed.
