The effect of testing temperature on corrosion-erosion resistance of martensitic stainless steels

Conventional AISI 420 and high-nitrogen martensitic stainless steels were tested under corrosion-erosion conditions in slurry composed by substitute ocean water and quartz particles. The tests were performed at 0, 25, and 70 degreesC, with mean impact angles of 20 and 90degrees. Polarization tests in H2SO4 solution containing chloride ions were also carried out at the same temperatures. Both conventional and high-nitrogen specimens were tempered at 200 and 450 degreesC before the tests. The high-nitrogen specimens were produced through gas nitriding of AISI 4 1 OS (13%Cr-0.03%C) and AISI 410 (13%Cr-0.15%) stainless steels at I 100 degreesC. These treatments allowed obtaining interstitial contents (nitrogen + carbon) at the surface of the specimens equivalent to the carbon content of conventional AISI 420 stainless steel. The best corrosion-erosion resistance was obtained in the nitrided AISI 41 OS samples tempered at 200 degreesC and tested at 0 degreesC under 20degrees-impact angle. Increasing testing temperature led to higher mass losses and wear rates due to the intensification of intergranular and pitting corrosion mechanisms, especially in the conventional AISI 420 stainless steels. In tests performed at 0 and 25 degreesC, a reduction in the wear rate for longer testing times was observed, which was mainly associated to fragmentation and roughness changes of the abrasive particles. The mass losses under normal impact conditions were systematically higher than under oblique incidence, and some evidences of mass removal by brittle fracture were found after SEM examination of the worn surfaces. (C) 2003 Elsevier Science B.V. All rights reserved.