Porovnání metod pro hodnocení odolnosti ocelí vůči sulfidickému praskání pod napětím

Abstract

In the field of classification of material tolerance compared with hydrogen cracking, rather in environments containing hydrogen sulfide, there has been all row of testing method. These methods are certified by internationally reputable norms NACE and ASTM. In following diploma work I deal with the comparison of two methods evaluating of material tolerance against sulfide stress cracking – SSC respectively Constant-Strain Type of Stressing Frame and Four-Point Loaded Specimen. Confrontation was effected on thermomechanical rolled metal plate X65 based on API 5L. On the ground of objective comparison specimens were loaded every time in the same way, situated in the same corrosive environment during 720 hours and 240 hours. After exposition metallographic cuts were made on specimens and with usage of optical and electron microscopy rate of their degradation was evaluated. It is possible to say, that bigger corrosive destroyed was found for specimens loaded Four-Point Loaded Specimen, when in general matrix small scratches were found. Specimens after exposition 240 hours appeared to be subjectively less resistant.