45钢表面Ni基激光熔覆层的耐蚀性能

为改善45钢表面的力学性能和耐蚀性,在相同功率下采用不同扫描速率在其表面激光熔覆制备了Ni基（Ni35A）复合涂层。利用金相显微镜、X射线衍射仪、显微硬度计和电化学腐蚀测试系统对熔覆试样进行组织形貌、相组成、显微硬度和耐蚀性能分析。结果表明：熔覆试样由熔覆层、结合区和基体3部分组成;熔覆层组织细密并与基体冶金结合,扫描速率过大时易形成裂纹;熔覆层主要由FeNi,和Ni,B相组成,不同速率所得熔覆层显微硬度均超过400HV;扫描速率为500mm／min时熔覆试样自腐蚀电位提高了40mV。

Corrosion Resistance of Nickel-Based Laser Cladding Coating on 45 Steel

Ni-matrix composite coatings(Ni35A) were prepared on the surface of 45 steel by laser cladding under a fixed power but varying scanning rate so as to improve the mechanical properties and corrosion resistance of the steel.The morphology and phase composition of the laser cladding coatings were analyzed using a metallographic microscope and an X-ray diffractometer.The hardness of the laser cladding coatings was measured using a hardness meter,and their corrosion resistance was evaluated using an electrochemical corrosion test rig.It was found that as-prepared laser cladding coatings consisted of cladding layer,binding zone and substrate.The cladding layer had fine structure and metallographic binding with the substrate,but excessive large scanning rate caused cracks in the cladding layer.Moreover,the cladding layer was composed of FeNi3 and Ni3B.The laser cladding coatings obtained under different scanning rates all possessed hardness of over 400 HV,and the one obtained under a scanning rate of 500 mm/min had a higher corrosion potential.