为了提高碳钢的表面性能,在45#钢表面制备Ni-P-纳米Al2O3化学复合镀层,再通过脉冲Nd:YAG激光对镀层表面进行强化处理。利用光学显微镜(OM)和扫描电子显微镜(SEM)观察镀层在脉冲激光处理前后的表面形貌与截面微观组织,利用X射线能谱仪(EDS)对截面进行元素分析,用X射线衍射仪(XRD)对脉冲激光处理前后镀层进行物相分析,用显微硬度计测量镀层截面硬度分布。结果表明,镀层经脉冲激光处理后,由表及里分为树枝晶区、胞晶区、柱状晶区、熔合区、热影响区(HAZ),并与基体形成冶金结合;镀层由非晶态转变为晶态,生成Al5FeNi,FeNi及Fe0.64Ni0.36等金属间化合物;强化层最高硬度较未经激光处理的复合镀层提高1.7倍,较基体提高4.5倍,这是硬质相粒子弥散强化及马氏体相变强化综合作用的结果。 In order to improve the surface properties of carbon steel, the Ni-P-nano-Al2O3 composite coating was prepared on the surface of 45 # steel and the surface of the coating was strengthened by pulsed Nd: YAG laser. The surface morphology and cross-section microstructure of the coating before and after pulsed laser treatment were observed by optical microscope (OM) and scanning electron microscope (SEM). The cross-section was analyzed by X-ray energy dispersive spectrometer (EDS) XRD) phase analysis of the coating before and after pulsed laser treatment, hardness distribution of the coating section was measured with a microhardness tester. The results show that the coating is divided into dendrite zone, cell zone, columnar zone, fused zone and heat affected zone (HAZ) from the surface and the surface after pulsed laser treatment, and forms a metallurgical bond with the substrate. The coating consists of amorphous Into the crystalline state, resulting in Al5FeNi, FeNi and Fe0.64Ni0.36 and other intermetallic compounds; the highest hardness of the reinforcement layer than without laser treatment of composite coatings increased 1.7 times, compared with the matrix increased 4.5 times, which is the dispersion of hard phase particles dispersion And martensite transformation strengthening the combined effect of the results.