Influence of Laser Energy Density on Acquisition and Wear Resistance of Bionic Semisolid Unit of 40Cr Steel

40Cr steel is one of the most common materials for manufacturing brake camshaft of trailer. The brake camshaft is subjected to extreme wear during its service life. In order to enhance wear resistance, medium frequency induction hardening (MFIH) treatment is usually conducted on the surface of brake camshaft. However, conventional MFIH technique requires heating of the entire surface, which has the drawbacks of more power consumption, high production cost and easy deformation. Therefore, inspired by the bionic theory, a process named as "laser bionic semisolid treatment" method accompanied by favorable surface roughness and minimum distortion has been proposed herein as an alternative to MFIH method. By this means, bionic units with different surface roughness, sizes microstructure and hardness were manufactured on the surface of 40Cr steel. Then, the wear resistance of 40Cr steel with various laser energy densities was experimentally investigated. The results demonstrated that when the laser energy density was 18.00-3+3 J/mm(2), the bionic semisolid unit was obtained with the arithmetic mean surface roughness R-a of 1046.81 nm. Moreover, there was a significant improvement in the wear resistance of 40Cr steel due to the microstructure and higher hardness compared with the untreated sample, and its weight loss ratio was decreased by 71.90%. The mechanism of wear resistance enhancement was also discussed.