Enhanced wear resistance and wettability of 20Cr2Ni4A steel by supersonic fine particle bombardment treatment.

A grain fine surface plastic deformation layer with a thickness of about 108.6 ± 1.5 μm was fabricated on 20Cr2Ni4A steel by supersonic fine particle bombardment (SFPB). The microstructure, wettability, and tribological properties of original and SFPB-treated (including Co-SFPB samples: activated carbon was added to the bombarded powder (Al₂O₃) followed by SFPB; Precoat + SFPB samples: the activated carbon is precoated on the surface of the original material followed by SFPB) low carbon steel were characterized by optical microscope (OM), scanning electron microscope (SEM), static water contact angle, friction, and wear test. The results show that SFPB can refine the surface microstructure and the grain size is about 21 nm. The surface hardness is as high as 428.1 HV_0.2, which is 89.3% higher than the original samples. Compared with the residual stress of the original samples (− 116.7 MPa), the residual stress on the surface of Precoat + SFPB samples (− 333.8 MPa) is significantly increased. The measurement results of static water contact angle illustrate that Precoat + SFPB samples have the best hydrophobicity (133.4°). After the treatment of SFPB, 20Cr2Ni4A steel is worn for a certain time, combined with the comprehensive analysis results of friction coefficient, mass loss, and wear morphology, Precoat + SFPB samples have the best wear resistance, which is due to its high surface hardness, large residual compressive stress, and the alloying layer formed by pre-coating activated carbon under the SFPB. [ABSTRACT FROM AUTHOR]