Influence of temperature and stress state on the TWIP behavior of 201LN and 316LV austenitic stainless steels

Abstract

The present results analyzed deformation behavior under tension and compression of two different austenitic stainless steels: AISI 201LN, with low nickel content and stabilized with Mn and N; and AISI 316LV, stabilized with Ni and with low content of interstitial atoms. Mechanical tests were performed at a strain rate of 10−3 s−1 and at temperatures varying from −100 to 600 °C to yield comparable values of the stacking fault energy (SFE). The resulting microstructure was analyzed by X-ray diffraction and EBSD. The stress-strain curves were analyzed using the Kocks-Mecking (K-M) approach. For comparable stacking fault energies, temperature enhances the thermal activation effects that led to lower fraction of mechanical twins in the 201LN compared with the 316LV. The crystallographic re-orientation followed the flow rule irrespective of the temperature and deformation mechanism: tension and compression experiments showed the ⟨111⟩ or ⟨110⟩ orientation with the tension axis, respectively. In tension, the dislocation storage and recovery factors of the K-M model were larger than in the compression and the amount of stored dislocations and crystallite size reflect these effects. In the compression, the TWIP effect was reduced for the 316LV and suppressed for the 201LN.