Investigation On Hot Defomation Behavior and Hot Processing Maps Of 316LN Strainless Steel

Abstract:

Isothermal compression tests of 316LN stainless steel at temperatures ranging from 1000 to 1200 oC and strain rates from 0.01 to 10 s-1 were performed on Gleeble thermo-simulation machine. Based on hyperbolic sine function, the constitutive equations of 316LN stainless steel and hot processing maps during the hot deformation process were established. The flow stresses were corrected via considering the temperature rise induced by plastic deformation and friction during the test process. In addition, by taking the influence of strain on flow stress into account, a unified constitutive model for predicting flow stress was proposed. The flow stress predicted by the constitutive equations shows good agreement with the corrected stress under the situation that R is 0.992 and ARRE is 4.43%. According to dynamic material model presented by Prasad, hot processing maps for hot working condition were established based on exploring the effect of power dissipation and instability coefficient associated with various kinds of temperatures and stain rates. Subsequently, efficiency of power dissipation and instability coefficient were interpreted based on hot processing maps under a series of strain, temperatures and strain rates. The results show that efficiency of power dissipation increases gradually with the increasing temperature and the decreasing stain rate, and note that the maxium of efficiency of power disspation is 0.38. An optimun zone for 316LN stainless steel is obtained and verified effectively by the analysis of microstructure.

Key words:316LN stainless steel; constitutive model; hot processing maps; hot deformation behavior