PSI - Issue 14

Sourabh Shukla et al. / Procedia Structural Integrity 14 (2019) 259–264 Sourabh shukla et al./ Structural Integrity Procedia 00 (2018) 000–000

264

6

Table 4. DOS of CW & TA samples SA

700°C

900°C

0% CW 25% CW 45% CW

14.26 58.92 41.12

33.52 82.41 65.34

63.98 72.59 20.81

It is evident that during CW, large number of dislocations formed not only near grain boundary but also under the grains, S. Pednekar et al. (1980). Thus after thermal ageing, those dislocations becomes active and causes more carbides formation at the grain boundaries as well as grain area which results in increase in DOS. As microstructure of 700 °C shows those dark spots which are the carbides formed inside the grains and grain boundaries, Srinivas et al. (1980). But as TA temperature increases upto 900 °C, dislocation density decreases which helps to form a new set of reverted austenite having low energy grain boundary. Due to this low energy, Cr will not be able to diffuse and hence, it decreases formation of Cr 23 C 6 precipitation which results in decrease in DOS. According to Wang et al. (2016), the recrystallization of grains or grain refinement causes decreases in the DOS. This explains why on higher thermal ageing for high cold work samples the DOS decreases. 5. Conclusion XRD analysis revealed that the for SA cold work condition, volume fraction of strain induced martensite increased with increases in the cold work but after thermal ageing, it decreased with increase in ageing temperature. As cold work percentage increases from 0% to 25%, DOS increases for all thermal aged conditions whereas decreases from 25% to 45% CW. During thermal ageing at 45% cold work at 900°C, it results in grain refinement which helps to decrease the DOS. References A. J. Sedriks., 1996. Corrosion of Stainless Steels. 2nd ed., J. Wiley & Sons, 13, New York. Raghuvir Singh, 2008. Influence of cold rolling on sensitization and intergranular stress corrosion cracking of AISI 304 aged at 500 ̊ C. J Mater Process Technol, 206(1-3), 286–293. W. E. White, 1992. Observations of the influence of microstructure on corrosion of welded conventional and stainless steels, Mater. Charact.,28 (3), p 349-358. Maksimova OP, 1999. Martensite transformations: history and laws. Met Sci Heat Treat 41, 322–339. Fukuda T, 2006. Effect of high magnetic field and uniaxial stress at cryogenic temperatures on phase stability of some austenitic stainless steels. Mater Sci Eng A, 438–440, 212–217. Das A, 2008. Morphologies and characteristics of deformation induced martensite during tensile deformation of 304 LN2 stainless steel. Mater Sci Eng A, 486, 283–286. Berrahmoune MR, 2006. Delayed cracking in 301LN austenitic steel after deep drawing. Mater Sci Eng A, 438–440, 262–266. Wang J. and Zhang L.F., 2017. Effects of cold deformation on electrochemical corrosion behaviors of 304 stainless steel. Anti-Corros. Methods Mater. 64(2), 252-262. C. L. Briant and A. M. Ritter, 1979. The effect of cold work on the sensitization of 304 stainless steel. Scr. Metall, 13, 177-181. S. Pednekar and S. Smialowska, 1980. The effect of prior cold work on the degree of sensitization in type 304 stainless steel. National association of corrosion engineers (NACE), 26, 10. M. Srinivas, R.P. George*, C. Mallika and U. Kamachi Mudali, 2007. Influence of Cold Work on Sensitisation Kinetics and Evaluation of degree of Sensitization in 316LN Stainless Steels. Corrosion Science and Technology Group. F.J. Humphreys and M. Hatherly, 2004. Recrystallization and related annealing phenomena. Second edition. L. V. Jin-long, and Luo Hong-Yun, 2012. Influence of tensile pre-strain and sensitization on passive films in AISI 304 austenitic stainless steel. Material chemistry and physics, 135, 973-978. Rui Kun Wang, Zhi Jun Zheng, and Yan Gao, 2016. Effect of Shot Peening on the Intergranular Corrosion Susceptibility of a Novel Super304H austenitic Stainless Steel. JMEPEG, 25, 20–28.