The effect of non-metallic inclusions on high-cycle fatigue resistance of powder metallurgically (P/M) fabricated and hot isostatically pressed (HIP) duplex stainless steels (DSSs) was investigated with axial fatigue test specimens in a chloride and sulphate containing aqueous solution at room temperature. The inclusion content of the studied materials was analysed with bulk oxygen content measurements as well as with optical and digital inclusion analysis methods. Fatigue crack initiation was observed to take place at material defects, i.e., on contaminated prior powder-particle boundaries or, especially, at oxide inclusions. Localised corrosion was not noticed at the initiation sites. Material defects had an especially pronounced effect on fatigue properties, when the stress ratio was R = 0, but their effect decreased, when the calculated stress intensity factor was reduced below a certain value. Moreover, the change of the stress ratio from R = 0 to R= -1 decreased the difference in high-cycle corrosion fatigue properties between P/M-HIP DSSs with different inclusion contents.
|Julkaisu||Fatigue and Fracture of Engineering Materials and Structures|
|DOI - pysyväislinkit|
|Tila||Julkaistu - 1996|
|OKM-julkaisutyyppi||A1 Julkaistu artikkeli, soviteltu|