Pearlite-based quenched and tempered steel: Effect of ghost pearlite on strain-rate dependent compressive behavior and adiabatic shear band formation

The influence of ghost pearlite (GP) on the strain-rate-dependent compressive behavior and adiabatic shear band (ASB) evolution of Mn-partitioned pearlite-based quenched and tempered steel was systematically investigated. Three microstructures containing 0%, 26%, and 50% GP were produced by controlling the austenitization time. Dynamic compression tests were conducted using a split Hopkinson pressure bar at strain rates ranging from 1.5 × 10³ s⁻¹ to 4.7 × 10³ s⁻¹. The GP microstructure consists of alternating layers of Mn-enriched film-like retained austenite (RA) and Mn-depleted lath martensite. Increasing the GP fraction enhanced the dynamic mechanical performance and resistance to dynamic fracture. During deformation, the film-like RA absorbed part of the deformation energy through deformation-induced martensitic transformation, thereby delaying strain localization and the evolution of ASBs. The stability of RA was found to play a critical role in governing ASB initiation and propagation. The specimen containing RA with lower stability in lower fraction of GP exhibited the greatest resistance to ASB initiation, whereas the specimen containing a higher fraction of GP with relatively higher stability of RA showed the strongest resistance to ASB propagation and the highest critical fracture strain rate. These findings provide new insights into the microstructural design of advanced high-strength steels with improved resistance to dynamic deformation and catastrophic failure.