Effects of nitrogen, niobium and molybdenum on strengthening of austeniticstainless steel produced by thermo-mechanical control process

Citation
M. Tendo et al., Effects of nitrogen, niobium and molybdenum on strengthening of austeniticstainless steel produced by thermo-mechanical control process, ISIJ INT, 41(3), 2001, pp. 262-267
Citations number
21
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Metallurgy
Journal title
ISIJ INTERNATIONAL
ISSN journal
0915-1559 → ACNP
Volume
41
Issue
3
Year of publication
2001
Pages
262 - 267
Database
ISI
SICI code
0915-1559(2001)41:3<262:EONNAM>2.0.ZU;2-Q
Abstract
Thermo-mechanical control process (TMCP) applied to high nitrogen austeniti c stainless steels could produce high-strength thick plates with a 0.2 % pr oof stress of higher than 600 MPa. The effects of nitrogen, niobium and mol ybdenum on the strengthening have been examined by hot compression tests ar ound 1 223 K. The hardness of the compressed specimens linearly increased w ith increasing the nitrogen content, and the increment in hardness was larg er than that of the specimens in a recrystallized state. This could be expl ained in terms of enhanced work-hardening by nitrogen addition during hot c ompression. in fact, the flow stress linearly increased with increasing the nitrogen content. The planar dislocation structure observed in the specime ns with high nitrogen contents also gave evidence that nitrogen affected th e work-hardening behavior. Although it was not clear that nitrogen affected dislocation glide or dynamic recovery, it could be predicted that nitrogen addition was effective in increasing the dislocation density. Since niobiu m (similar to0.1 mass%) had a marked effect on retarding the static recryst allization, probably owing to the fine precipitates of NbN, niobium additio n is an effective way to prevent softening before accelerated cooling in TM CP.