Understanding the effect of nitrogen in austenitic stainless steel on the intergranular stress corrosion crack growth rate in high temperature pure water

作者：Roychowdhury S^*; Kain V; Neogy S; Srivastava D; Dey G K; Prasad R C

来源：Acta Materialia, 2012, 60(2): 610-621.

DOI：10.1016/j.actamat.2011.09.053

• Stainless steel
• Stress corrosion cracking
• Transmission electron microscopy
• Twinning
• Strain hardening

Understanding the effect of nitrogen content on the crack growth rate (CGR) due to intergranular stress corrosion cracking (IGSCC) in high temperature (288 degrees C) pure water, in non-sensitised and strain-hardened stainless steel (SS) type 304 LN was the focus of this study. Non-sensitised SS containing two different levels of nitrogen (0.08 and 0.16 wt.%) in the solution annealed condition was strain-hardened by cross-rolling at 200 degrees C (warm rolling). It has earlier been reported that SS with a higher nitrogen level in the warm rolled condition has a higher CGR in high temperature pure water. Tensile testing was carried out using both the SS in the warm rolled as well as in the solution annealed condition at 288 degrees C. Samples were prepared for transmission electron microscopy (TEM) from the warm rolled SS and from the tensile tested (at 288 degrees C) specimens. TEM studies indicated that twinning and shear band formation were the major modes of deformation due to rolling at 200 degrees C and these feature were observed to terminate at grain boundaries, leading to regions of higher strain and stresses at grain boundaries. Higher nitrogen SS has higher grain boundary strain and stresses making the grain boundary regions more susceptible to IGSCC, resulting in higher CGR values. At 288 degrees C dislocation entanglement and cross-slip were the predominant modes of deformation.

• 出版日期2012-1