화학공학소재연구정보센터
Materials Science Forum, Vol.426-4, 987-992, 2003
Thermomechanical strengthening of nitrogen -bearing austenitic stainless steels
The effects of thermomechanical controlled processing (TMCP) parameters on the mechanical properties and dislocation structure in nitrogen-bearing austenitic stainless steels X2CrNiN 187 (type 30ILN) and 06C20Cr12Ni012N(2)NbV have been studied. The experiments were carried out on a Gleeble 1500 thermomechanical simulator and a laboratory rolling mill. The importance of dynamic and static recrystallization processes at various temperatures between 800 -1200degreesC, strains between 0.2 - 0.9, and elapsed times up to 60 s between the finish of deformation and the start of cooling has been evaluated. The mechanical properties were determined by the flow stress curves at high and ambient temperatures using compression and tensile tests as well as hardness measurements. Microstructure examinations were carried out using optical and electron microscopes. It was observed that TMCP at the specific combination of temperature-strain-time parameters within the examined scope of the factorial space can promote a noticeable strength improvement; the yield strength of X2CrNiN 187 increasing up to 500 MPa and that of 06C20CrI2Ni012N(2)NbV to 800 MPa as a result of fragmented dislocation substructure in addition to the fine precipitates formed in the latter steel.