PSI - Issue 14

Hari Krishan Yadav et al. / Procedia Structural Integrity 14 (2019) 605–611 Hari Krishan Yadav/ Structural Integrity Procedia 00 (2018) 000–000

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resulted in the formation of larger grains with lesser precipitations Blum and Eisenlohr (2009). Recovery, recrystallization and precipitation of fine titanium carbide were influencing the creep life of material. As the amount of deformation increased, large number of dislocations also increased linearly, Kesternich and Meertens (1986). However, precipitations of those fine carbides were limited and the interaction with dislocations was possibly lesser in CW4. This made the movement of dislocations relatively easier and the presence of high temperature and stress led to faster recovery and recrystallization in CW3 and CW4 as compared to that of in CW2. Hence, CW2 sample was observed to be most creep resistant among others at stress level of 200 MPa. 4. Conclusion From present investigation of effect of cold work on creep behavior of 14Cr-15Ni austenitic stainless steel, following conclusions were derived:  Higher dislocation density increased the hardness in each cold work sample as compared to mill annealed sample.  Creep strength (for 200 MPa stress level) increased with degree of cold work upto 20% and then decreased with 40% cold worked sample exhibited least rupture life. Precipitations of titanium carbide as well as phenomenon of recovery and recrystallization were responsible for observed variation. Reference Todd, J.A., Ren, J.C., 1989. The effect of cold work on the precipitation kinetics of an advanced austenitic steel. Materials Science and Engineering A 117, 223–245. Tateishi, Y., 1989. Development of long life FBR fuels with particular emphasis on cladding material improvement and fuel fabrication. Journal of Nuclear Science and Technology 26(1), 132–136. Venkadesan, S., Bhaduri, A.K., Rodriguez, P., Padmanabhan, K.A., 1992. Effect of ageing on the microstructural stability of cold-worked titanium-modified 15Cr-15Ni-2.5 Mo austenitic stainless steel. Journal of Nuclear Materials 186(2), 177–184. Kesternich, W., Rothaut, J., 1981. Reduction of helium embrittlement in stainless steel by finely dispersed TiC precipitates. Journal of Nuclear Materials 104, 845–852. Yadav, H.K., Ballal, A.R., Thawre, M.M., Vijayanand, V.D., 2018. Microstructure evolution during creep of cold worked austenitic stainless steel. IOP Conference Series: Materials Science and Engineering 346, 012020. Jang, M.H., Kang, J.Y., Jang, J.H., Lee, T.H., Lee, C., 2018. Microstructure control to improve creep strength of alumina-forming austenitic heat resistant steel by pre-strain. Materials Characterization 137, 1–8. Kesternich, W., Meertens, D., 1986. Microstructural evolution of a Titanium-stabilized 15Cr-15Ni steel. Acta Metallurgica 34(6), 1071–1082. Vijayanand, V.D., Parameswaran, P., Nandagopal, M., Selvi, S.P., Laha, K., Mathew, M.D., 2013. Effect of prior cold work on creep properties of a titanium modified austenitic stainless steel. Journal of Nuclear Materials 438(1-3), 51–57. Latha, S., Mathew, M.D., Parameswaran, P., Rao, K.B.S., Mannan, S.L., 2008. Thermal creep properties of alloy D9 stainless steel and 316 stainless steel fuel clad tubes. International Journal of Pressure Vessels and Piping 85(12), 866–870. Latha, S., Mathew, M.D., Parameswaran, P., Nandagopal, M., Mannan, S.L., 2011. Effect of titanium on the creep deformation behaviour of 14Cr–15Ni–Ti stainless steel. Journal of Nuclear Materials 409(3), 214–220. Blum W., Eisenlohr P., 2009. Dislocation mechanics of creep. Materials Science and Engineering A 510, 7–13.