Formation of sliding friction-induced deformation layer with nanocrystalline structure in T10 steel against 20CrMnTi steel

•The dry sliding tribological tests of T10 steel against 20CrMnTi steel were carried out.•The evolvement of microstructure in Tribolayer was investigated.•The two layers were formed beneath the worn surface of tribopairs.•The ultrafine grains on the worn surfaces of T10 and 20CrMnTi were observed.

Nanocrystalline structures in the worn surfaces of quenched and tempered steels were obtained in a dry sliding friction process. The ultrafine and even nano grains with sizes about 50 nm and 200 nm were observed in the sliding friction-induced deformation layers (SFIDLs) of 20CrMnTi disc and T10 steel pin. The mechanism of forming nanocrystalline structure in SFIDLs was elucidated as the result of severe shear deformation induced by dry sliding friction. Two methods for estimating shear stain as proposed by Douthwaite and Sato, respectively, were used to evaluate their induced equivalent strains and to obtain the critical shear strains for ultra-refined or nanocrystalline structures formation in the worn surfaces.