The interlamellar spacings of pearlitic steels gradually increase as the isothermal transformation temperatures, correspondingly, the tensile strengths decrease, satisfying the Hall–Petch relationship. Si virtually completes its partitioning process during the eutectoid transformation. A depletion of Mn and an accumulation of Si are found in the concentration profiles of 0.95%-Si steel transformed at 793 K in the ferrite, but not in 0.22%-Si steel. It may attribute them to the Si–Mn diffusional flux couplings, which due to the strong interaction between Si and Mn atoms in the α-Fe. Transformation temperature increases to 873 K, a large amount of Mn atoms coming from ferrite cannot timely diffusion to cementite lamella core, forming a localised retention of Mn in the cementite phase side nearby the interface. This is part of a thematic issue on Pearlitic Steel Wires.

The microstructures of B bearing cast steel (B steel) containing 0?8-1?2 wt-%B, 0?8-1?2 wt-%Cr, 1?0-1?5 wt-%Mn, 0?6-1?0 wt-%Si and 0?10-0?25 wt-%C have been characterised by means of optical microscopy, scanning electron microscopy, electron probe microanalyser and X-ray diffraction. The solidification structure of B steel consists of pearlite, ferrite, martensite and boride (Fe 2 B), while the hardness is 1430-1480 HV. Borides distribute along the grain boundary in the form of eutectic. Fine lath martensite and eutectic Fe 2 B can be obtained by water quenching at 1223-1273 K. The hardness and impact toughness of the B steel exceed 55 HRC and 150 kJ m 22 respectively. The abrasion resistance determined using a pin abrasion tester is obviously higher than that of the martensitic cast steel and nears to the high chromium white cast iron.

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The site preference of Mn in alloyed cementite is investigated by using X-ray diffraction (XRD) and first-principles calculations. First-principles calculations of the cohesive energies and formation energies of Mn-alloyed cementite indicate that Mn atoms prefer to substitute the 8d sites of cementite. The calculation results of density of states (DOS) and charge-density difference show that the more stable outermost electron orbital of Mn (3d 5 4s 2 ) may be the main reason for the site preference of Mn at 8d sites in Mn-alloyed cementite. In addition, the experimental XRD spectrum of 25 at.% Mn-alloyed cementite, which is prepared by using mechanical alloying combined with spark plasma sintering, highly coincides with the calculated XRD spectrum of Mn 8d-substituted cementite, verifying that Mn atoms prefer to substitute the 8d sites of alloyed cementite.

The atomic interactions between Si and Mn during eutectoid transformation in high-carbon pearlitic steel were investigated. Atom probe tomography and first-principles calculations were applied to evaluate and analyze the atomic interactions at the ferrite/cementite interface. In the initial stage of eutectoid transformation, enrichment of Si and Mn occurred at the ferrite and cementite sides, respectively, of the interface. This interfacial segregation phenomenon gradually diminished as the transformation proceeded. Calculations of the cohesive energy and formation energy revealed a clear enhancement in the chemical bonding and stability of the pearlite system when the Si atom was moved from the ferrite layer to the cementite layer and the Mn atom was moved in the opposite direction. The interfacial segregation of the Mn and Si atoms was mainly responsible for the insufficient diffusion and high hybridization degree of Fe, Mn, Si, and C atoms. Furthermore, the partitioning ratio of Mn in high-Si steel was greater than that in low-Si steel, leading to greater partitioning of Mn into the cementite phase. Calculations of the electronic structure revealed that the enrichment of Si in the ferrite phase promoted the partitioning of Mn into the cementite phase owing to the strong repulsive force between Mn and Si at the pearlitic interface.