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Abstract

WHEN THE FENIRC ALLOY 800 IS EXPOSED TO A MIXTURE OF H(2)S, CO AND H(2)O (AS WELL AS TO A CO FREE GAS OF THIS COMPOSITION AT 800 C AND TOTAL PRESSURE OF 1.5 BAR), INTERNAL AS WELL AS EXTERNAL CORROSION TAKES PLACE AND SULPHIDES, OXIDES AND CARBIDES ARE FORMED. CORROSION RESULTS IN A DECREASE OF CREEP STRENGTH UNDER HIGH LOAD WHILE IT REMAINS PRACTICALLY UNCHANGED OR IS EVEN IMPROVED UNDER MEDIUM AND LOW LOAD. THE UNEXPECTED ABSENCE OF NICKEL SULPHIDE FORMATION IN THE ABOVE GAS MIXTURE IS ATTRIBUTED TO THE COMPARATIVELY LOW NICKEL ACTIVITY IN THE ALLOY SO THAT SULPHIDE FORMATION WOULD OCCUR ONLY AT SULPHUR PARTIAL PRESSURES EXCEEDING THE PRESSURES USED IN THIS INVESTIGATION. THE INCREASE RATE OF CRACK PROPAGATION UNDER LOAD CAN BE INTERPRETED IN TERMS OF THE CRACKING OF THE OXIDE SURFACE LAYER ON THE METAL, THE CRACKS ALLOWING THE AGGRESSIVE GAS TO PENETRATE FREELY TO THE METAL SURFACE. THE TESTS WITH THE CO FREE GAS DEMONSTRATE THAT THE STRENGTH LOSS IS PRINCIPALLY CAUSED BY SULPHIDATION AND OXIDATION WHILE CARBURISATION, WHICH LEADS TO A STRENGTHENING, RESULTS IN SOMEWHAT SLOWER DESTRENGTHENING RATE.

Additional information

Authors: GUTTMAN V, JRC-PETTEN;TIMM J JRC-PETTEN, JRC-PETTEN
Bibliographic Reference: WERKSTOFFE UND KORROSION, VOL. 39, PP 322-331, 1988
Record Number: 1989126212700 / Last updated on: 1989-04-01
Category: PUBLICATION
Available languages: en