Improving creep strength of 316L stainless steel by alloying with nitrogen

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2012-02, Vol.535, p.76-83
• Main Authors: Mathew, M.D., Laha, K., Ganesan, V.
• Format: Article
• Language: English
• Subjects: 316L; Applied sciences; Austenitic stainless steels; Creep; Creep (materials); Creep rupture; Creep rupture strength; Creep strength; Creep tests; Damage; Exact sciences and technology; Heat resistant steels; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Nitrogen; Reactor; Rupture; Stainless steel
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2011.12.044

► Nitrogen was found to be beneficial to creep properties at all the stress levels. ► Creep rupture life increased almost 10 times by increasing nitrogen content from 0.07wt.% to 0.22wt.%. ► The extent of internal creep damage and surface creep damage decreased with increasing nitrogen content. The influence of nitrogen on the creep behaviour of 316L(N) SS has been studied at nitrogen levels of 0.07, 0.11, 0.14 and 0.22wt.%. Creep tests were carried out at 923K at stress levels of 140, 175, 200 and 225MPa with rupture life up to 16,000h. Creep rupture strength was found to increase substantially with increase in nitrogen content; rupture life increased almost 10 times by increasing nitrogen content from 0.07wt.% to 0.22wt.%. Steady state creep rate decreased significantly with increasing nitrogen content. The extent of internal creep damage and surface creep damage decreased remarkably with increasing nitrogen content, resulting in increased creep rupture strength. Solid solution strengthening, increase in Young's modulus, decrease in stacking fault energy and matrix precipitation of carbonitrides have contributed to the increase in creep strength with increasing nitrogen content.