Grain refinement tracing of dynamic and metadynamic recrystallization for a Penetrator Steel

The present investigation is dealing with the evolution of simultaneous dynamic and metadynamic recrystallization (DRX) (MDRX) phenomena by physical simulation for a 4-strock hot compression process, where flow curves were presented for each stroke. The primary alloy is a penetrator steel containing 0.3% C in addition to some Cr, Mo, Ni and 1.63 W. Calculated grain size after the onest of DRX occurrence of MDRX decreases continuously with the increase of cumulative strain reaching to 0.289 µm. However, Electron Backscatter Diffraction (EBSD) investigation established that 99% of the grains, after the last compression stroke, were detected as 1.0 μm, with an average grain size 0.31 μm. Microstructure after simulation presents fine lath martensitic structure, coexisting with Cr-W carbides, which are crammed at the inter- martensite laths. Furthermore, 56% of the grains showed grain boundaries misoriention creating High Angle Grain Boundaries (HAGBs), which are promoting MDRX. The flow curve of each stroke definitely contains two complementary microstructure events, namely a DRX , and a MDRX phenomenon, where the peak stress (σp) of DRX is inversely proportional to the mean temperature of stroke.