Corrosion Fatigue Crack Initiation in Duplex Stainless Steel Paper Making211 Components

摘要

The demand for more cost-effective paper production has generated a strong211u001edriving force for wider and faster paper machines. As a result, the reliability 211u001eand durability of the metallic components in those machines have become pivotal 211u001eissues and as such, increased the awareness of the enormous economic impact 211u001eassociated with equipment repair and replacement throughout the pulp and paper 211u001eindustry. A good example of this problem has been reported by Sandusky 211u001eInternational, the sole US based producer of suction roll shells for the paper 211u001eindustry. This company produces two duplex stainless steel alloys with very 211u001esimilar compositions and the performance predictions based on laboratory 211u001emeasurements and current life prediction methods indicate that the behaviors of 211u001ethese two alloys should be virtually identical in service. However, in the ten 211u001eyear period since the development of these alloys, Sandusky has not experienced a 211u001esingle service failure with one alloy while the other alloy continues to fail 211u001eprematurely. This research was primarily designed to develop a solution to the 211u001eproblem as reported by Sandusky International. Simply stated, that problem is: in-211u001eservice Alloy 75 corrosion fatigue failures occur even though the life prediction 211u001emethods indicate they should not. The existing measurement methods and 211u001einterpretations indicate that both Alloy 75 and Alloy 86 should have essentially 211u001eidentical corrosion fatigue behaviors, yet one alloy fails in service while the 211u001eother does not.