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.