Assessment of Stress Corrosion Cracking (SCC) Susceptibilities of Some OutokumpuProduced Stainless Steels in a River Harbour Mud Using Accelerated Test

SCC of metals as structural components can occur unexpectedly under tensile loads in environments with particular factors and its consequences are often calamitous. Metals of different types or structures have different levels of SCC susceptibility in different environments. It is desirous that this deleterious phenomenon be prevented with the understanding of relative performances of metals in all environments of their service applications. SCC susceptibilities of various ASTM-designated Outokumpu-produced stainless steels under stresses of 90% of their 0.2% offset yield strengths, with aqueous harbour mud from river Kaduna in Nigeria as the target environment were investigated in a laboratory study. A plate of each steel designation was used to produce six-bent beam corrosion test specimens in accordance with ASTM 36-99 test procedures. One specimen from each designation were submerged at a time in different admixtures of concentrated sulphuric acid and the mud at room temperature, 100oC and 200oC for one hour in each case and inspected at an optical magnification of 40 for any crack and the time at which it occurred. The obtained results for the tests gave an indication that none of the steel grades is susceptible to SCC in the mud under such working stresses and other conditions.