Kinetics of Uniaxial Tensile Flow and Work Hardening Behavior of Type 316L(N) Austenitic Stainless Steel in the Framewor
- PDF / 581,906 Bytes
- 14 Pages / 593.972 x 792 pts Page_size
- 107 Downloads / 282 Views
TRODUCTION
NITROGEN-ALLOYED low carbon grade AISI type 316L(N) austenitic stainless steel is widely used as a major structural material for sodium-cooled fast reactor (SFR) components in view of its good high temperature mechanical properties, improved resistance to stress corrosion cracking, compatibility with liquid sodium coolant, and adequate weldability.[1] The carbon content in the range 0.02 to 0.03 wt pct is preferred in order to minimize the susceptibility toward sensitization either during fabrication or during service and improve stress corrosion cracking resistance. Addition of nitrogen in the range 0.06 to 0.08 wt pct is intended to increase high temperature mechanical properties comparable to that of normal grade type 316SS. The beneficial influence of controlled addition of nitrogen on tensile, creep, and low cycle fatigue properties has been demonstrated in type 316L stainless steel.[2–5] The nitrogen added steel is also being considered as a candidate material for application in other nuclear facilities such as fusion reactors and accelerator-based systems.[6,7] Understanding of tensile flow and work hardening behavior of J. CHRISTOPHER, Scientific Officer-D, and B. K. CHOUDHARY, Scientific Officer-H, Head, are with the Deformation and Damage Modeling Section, Mechanical Metallurgy Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamil Nadu, India. Contact e-mails: [email protected]; [email protected] Manuscript submitted March 26, 2014. Article published online November 19, 2014 674—VOLUME 46A, FEBRUARY 2015
reactor structural materials attracts continued scientific and technological interest in view of improving the appropriate conditions for material processing and for reliable prediction of the performance of the components during service. Several empirical relations have been proposed to describe the flow and work hardening behavior of metals and alloys.[8–13] In these relationships, true stress is related to the true plastic strain as an external variable involving relevant additional terms defining work hardening characteristics. In this context, the one-internal-variable phenomenological approach by Kocks–Mecking–Estrin[14–17] has provided an excellent description of the mechanical response of metallic materials under unidirectional loading conditions. In the Kocks–Mecking (K–M) approach,[14,15] the evolution of dislocation density with plastic strain is assumed as a single internal state variable responsible for plastic flow and the strength of material is solely determined by the dislocation–dislocation interactions. The evolution of net forest dislocation density (qf) with plastic strain (ep) resulting from the competition between storage (hardening) and annihilation/rearrangement (recovery) of dislocations, which is assumed to be superimposed in an additive manner, is expressed as dqf 1 k2 q f ; ¼M bL dep
½1
where M is an average Taylor factor. The storage term is M/bL, where b is the Burgers vector and L is the METALLURGICAL AND MATERIALS TRANSACTIONS A
mean free pa
Data Loading...
