Effect of thermal aging on the room temperature tensile properties of AISItype 316LN stainless steel

Round tensile specimens of AISI type 316LN stainless steel, thermally aged at 1123 K for 0, 2, 10, 25, 100, 500 and 1000 h, were tested for tensile pr operties at room temperature at a strain rate of 7.7 x 10(-3) s(-1). The ch anges in tensile properties were correlated to the transmission electron mi croscopic studies. The various stages of nitrogen repartitioning including Cr-N cluster formation, intragranular and subsequent cellular precipitation of Cr2N were found to have a strong influence on the yield strength (YS) a nd ductility of the material. However, the changes in ultimate tensile stre ngth (UTS) with aging were negligible. The results of electrochemical extra ction of secondary phases clearly indicated a two-slope behavior. X-ray dif fraction analysis of electrochemically extracted residue suggested that the initial smaller sloped line corresponded to the precipitation of the Cr2N phase while the line with larger slope at longer aging time corresponded to the domination of chi phase precipitation. (C) 1999 Elsevier Science B.V. All rights reserved.