Effect of grain size on corrosion behaviour of sensitized Austenitic stainless steel (AISI 316) in H2SO4
Agbokwor Silas Ezedinma1,2 Simeon Ikechukwu Neife3
1Department of Mechanical Engineering, University of Nigeria Nsukka
2Mobil Producing Nigeria Unlimited (QIT-EKET)
3Department of Mechanical and Mechatronics Engineering, Faculty of Engineering
Alex Ekwueme Federal University, Ndufu Alike, Ebonyi State, Nigeria
Abstract
The effect of average grain sizes on the corrosion of desensitized austenitic stainless steel (AISI 316) in H2SO4 has been investigated. In order to induce desensitization, austenitic stainless steel (unwelded and welded AISI 316) samples were heated to 750oC and soaked at this temperature for different time intervals, followed by quenching in water. The grain sizes of the soaked samples of desensitized welded and unwelded AISI 316 were determined using BW optical metallurgical image analysis software. The corrosion rates of the samples were determined using a weight-loss method. The result showed that small grain sizes of the soaked unwelded AISI 316 favoured more improved corrosion resistance than the big grain sizes of the soaked welded AISI 316 at similar condition, as evidenced in the corrosion study. This result could be attributed to fine grain sizes that reduce the unit strain per grain boundary. Stresses resulting from relaxation using thermal homogenization treatment are better accommodated in the structure, minimizing the strain localization at individual boundaries.