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功率对暖通E690钢激光熔覆Ni60A涂层结构和摩擦性能的影响

Surface Modification of E690A Steel with Laser Cladded Ni60A Alloy Coatings

  • 摘要: 选择激光熔覆方法在暖通用E690高强钢表面制备Ni60A涂层,通过实验测试的手段研究不同激光功率条件下的熔覆层组织结构变化与耐磨性差异。研究结果表明:所有熔覆层都形成了清晰的分界面,各功率下试样形成的熔覆区厚度依次为90、310、380与650μm。功率1300 W时涂层的胞状晶尺寸最小,在合金组织内存在许多具有雪花形特征的共晶组织,形成了更细小晶体组织,经历均匀度也获得了提升,整体分布形态也最均匀。增大激光功率后,熔池获得了更优冶金条件,在熔覆层组织中生成更多细小晶粒。功率1300 W条件下涂层生成了CrNiC与CrFeNi强化相,使涂层获得了更高硬度并显著提升了耐磨能力。随着激光功率增大后,涂层摩擦系数表现出减小,在熔池中出现了更多SiC和基材组织结合,对基体组织发挥了明显的固溶强化作用,从而获得更优的韧性。

     

    Abstract: The surfaces of E690 steel, a widely used material for heating, ventilation and air conditioning(HVAC),was modified with the coatings deposited by laser cladding of Ni-based Ni60 A alloy powder.The influence of the laser power on the microstructures and tribological properties was investigated with X-ray diffraction and scanning electron microscopy and conventional mechanical probes.The preliminary results show that the laser power made the difference.Generally speaking, as the laser power increased, the thickness, hardness and wear resistance of the cladded layer increased, the grain-size and friction coefficient decreased, the uniformity and ductility improved.Cladded at 1300 W,the strengthening phases of CrNiC and CrFeNi formed in the 650 μm thick cladded layer, comprised the snowflake-like structures of the smallest eutectic grains.The formation of increasing SiC-density in molten spots brought about stronger interfacial adhesion, more solid solution strengthening and better ductility.

     

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