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工艺参数对蠕墨铸铁激光熔凝淬火带裂纹率和形貌的影响

Influence of process parameters on the cracking rate and morphology of the laser melting and quenching zone in vermicular graphite cast iron

  • 摘要: 采用3 kW固体光纤激光器在蠕墨铸铁基体上进行了激光熔凝淬火试验,分析了淬火带的裂纹率、熔凝区形貌、显微硬度和组织.结果表明,当保护气体流量一定时,提高激光功率或降低扫描速率有利于降低激光熔凝淬火带的裂纹率;而激光功率一定时,不同的扫描速率对应的最佳保护气体流量大小不同.随着激光功率的增加,淬火带形貌会向基体扩展,扩展规律是先主要沿熔凝区宽度和深度方向扩展,然后沿其它方向扩展,到一定程度后,又沿着宽度和深度方向扩展,如此循环,熔凝区总面积不断增加,淬火带形貌也由扁平状逐步变化为帽子状.

     

    Abstract: Laser melting and quenching experiments were conducted on vermicular graphite cast iron by employing 3 kW solid fiber laser. The cracking rate in the quenching zone,the morphology of the melting zone,microhardness and microstructure were analyzed. The results show that,at a given flow rate of shielding gas,increasing the laser power or reducing the scanning speed could facilitate the reduction of cracking rate in the quench zone. When the laser power was constant,the optimum flow rate of the shielding gas changed with the scanning speed. With the increase of laser power,the morphology of the quenching zone extended to the substrate. The morphology extended vertically and horizontally in the melting zone,and then in other directions. After that,it extended vertically and horizontally, and cycled. The gross area of the melting zone increased consequently, and the morphology of the quenching zone changed from flat to calyptra.

     

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