Studies of the tensile and corrosion fatigue behaviour of austenitic stainless steels

Corrosion fatigue behaviour of four types of austenitic stainless steels were investigated in boiling 45% magnesium chloride solution at a stress ratio of 0.25 and a frequency of 0.1 Hz. Type 316LN stainless steel possessed the best resistance and type 304 stainless steel had the lowest resistance to corrosion fatigue. XPS studies on the fracture surface indicated that the presence of nitrogen as NH4+ ion in the surface film of type 316LN stainless steel gave it the highest resistance to corrosion fatigue. Fractographic examination showed wholly transgranular cracking in all cases.

Research highlights
► Number of cycles to failure decreased with increasing mean stress.
► None of the stainless steels (SS) showed a fatigue limit.
► Type 316LN stainless steel showed the best resistance to corrosion fatigue (CF).
► Presence of NH4+ ion in the surface film helped increase the CF resistance of 316LN SS.