Slow strain rate testing for monitoring cracking of mild steels for vessels and pipes for processing using caustic solutions

Caustic cracking is a major infrastructure and safety concern in mild steel digesters, pipelines, refining and storage vessels in alumina processing and paper industries. This paper investigates application of slow strain rate (SSR) testing as a laboratory method to characterize caustic cracking susceptibility of mild steels. SSR tests were carried out at 120 °C in 200gpl NaOH at different strain rates (1.7×10−7 to 16×10−7 s−1). The results suggest that the mild steel is susceptible to caustic cracking in a very narrow window of strain rates (around 3×10−7 s−1). This study also supports SSR testing as a dependable laboratory testing technique for further studies.