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Static corrosion tests in LBE under oxygen-saturated and –depleted conditions at 500 °C for 1000 h were conducted to investigate the corrosion-induced diffusion layers on T91 and SS316L steels subject to dissolution and oxidation corrosion. Following nano-indentation experiments examined the variations of local mechanical properties within the corrosion layers. Under the present conditions, T91 steel showed better resistance to dissolution corrosion while higher susceptibility to oxidation corrosion against SS316L. For both steels, nano-indentation results showed a gradual decrease in mechanical properties from steel matrix to the corrosion side after dissolution corrosion. When subject to oxidation corrosion, the oxide scale formed on T91 steel showed lower Er-modulus and enhanced hardness in comparison with those of the steel matrix. An obvious decrease in both modulus and hardness was found at the interface between steel matrix and oxide scale.

Abstract: In the present work, ball indentation technique (BIT) has been employed to explore the possibilities for revealing the effect of cold rolling on mechanical properties on a SS316L steels. The as-received steel was cold rolled up to 40%. Results are presented for 7%, 15%, 24% and 40% of cold rolling effect on the SS316L steels. For all the specimen tested, the dependence of yield strength (YS), ultimate tensile strength (UTS), strength coefficient (K) and strain hardening component (n) values on cold rolling effect were made available from the BI results and they were validated with the standard conventional mechanical test results. It was found that, with increase in cold rolling the YS, UTS and K values have increased as revealed by BIT, while n value has decreased. Overall, it is found that BIT can be effectively used to determine the change of mechanical properties after cold working by using a small amount of test materials and quite rapidly compared to conventional test. An in-house developed BI system was employed to evaluate the mechanical properties. [Copyright &y& Elsevier]