Effect of hardness gradient of laser bionic coupling unit on wear resistance of 6082 aluminum alloy

•Bionic surfaces with various units hardness gradients were prepared by laser on 6082 Al alloy to imitate non-smooth surface of shells.•The units presented superior microstructure and hardness.•The wear resistance of Al alloy was increased by 72.57%.•The optimal unit hardness gradient distribution for wear resistance was obtained.•The wear resistance mechanism was deeply analyzed.